HONEYWELL
This is an unpublished work protected under the copyright laws ofthe United States and other countries. Should publication occur,then the following notice shall apply: COPYRIGHT 2000 HoneywellInternational Inc.
This document and all information and expression containedherein are the property of Honeywell International Inc. are loanedin confidence, and may not, in whole or in part, be used, dupli-cated, or disclosed for any purpose without prior permission ofHoneywell International Inc. These commodities may require anexport license for shipment outside the United States. Exportwithout an appropriate export license is contrary to U.S.law.
All rights reserved
Page i
131-9B Line Maintenance - Trainng Manual
FOREWORD
Information contained herein is intended as a general descriptionof operation which will permit maintenance and systematic trou-bleshooting of the subject system or components describedherein.
It is not the intent of the Honeywell International Inc. that thistraining study guide be used as a supplement to, or in lieu of, anyofficial publication. Contents herein are subject to change withoutnotice and are not exposed to the benefits of constant revision orupdate.
The reader of this manual is reminded that all values of pressure,temperature, speed, power, etc., are chosen for their illustrativemeaning only, and are not necessarily representative of actualvalues of any engine configuration. For actual values the applica-ble maintenance manual must be consulted.
The official publications pertaining to operating procedures, lim-its, and capabilities of the engine are the responsibility of the air-frame manufacturer.
The airframe manufacturer installs the engine in its airframe,designs, and/or manufacturers the electrical and mechanical con-trols, selects the instruments, and flight tests the aircraft.
The airframe manufacturer determines how, and under what limi-tations, the engine will be operated for all modes of aircraft oper-ation.
Honeywell International Inc. may suggest and advise -- but notdictate -- the operational and maintenance practices it feels arebest for the engine.
Some aircraft manufacturers will assimilate Honeywell Interna-tional Inc. manuals into their own publications, while other manu-facturers may simply refer the owner/operator to HoneywellInternational Inc. published manuals.
THIS TRAINING MANUAL HAS NO OFFICIAL STATUS. IN ALLINSTANCES, INFORMATION CONTAINED IN OFFICIAL PUBLICA-TIONS SHALL GOVERN.
Course GoalThis course is designed to provide maintenance personnel withthe training required to service, inspect, operate, and performline maintenance activities on the 131-9B Auxilaiary Powre Unitfollowing the procedures outlined in the applicable tehnical man-ula.
Notes:
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131-9B Line Maintenance Training Manual
Table of Contents
Chapter 1—Introduction and Description
Objectives ......................................................................................................................... 1-1Overview .......................................................................................................................... 1-2LRU Location .................................................................................................................. 1-4
Right View ................................................................................................................ 1-4Forward view ........................................................................................................... 1-6Left View .................................................................................................................. 1-8
Operating Specifications .............................................................................................. 1-10APU Design and Function .......................................................................................... 1-12Operating Envelope ...................................................................................................... 1-14Summary ......................................................................................................................... 1-16
Chapter 2—Installation and Interface
Objectives ......................................................................................................................... 2-1Overview .......................................................................................................................... 2-2APU Location .................................................................................................................. 2-4APU Installation .............................................................................................................. 2-6
APU Drain Manifold .............................................................................................. 2-8Aircraft Control/Display Interface ............................................................................ 2-10
Electronic Control Unit ....................................................................................... 2-12APU Master Switch .............................................................................................. 2-14APU Indication Panel ........................................................................................... 2-16APU Bleed Valve Switch ..................................................................................... 2-18APU Generator Switches ..................................................................................... 2-20APU Ground Control Panel ............................................................................... 2-22APU Fire Handle Switch ..................................................................................... 2-24
APU Start Sequence ...................................................................................................... 2-26Ready to Load (RTL) ............................................................................................ 2-28Environmental Control System Mode (ECS) .............................................. 2-30Main Engine Start (MES) .................................................................................... 2-30
APU Shutdown .............................................................................................................. 2-32Normal Shutdown ................................................................................................ 2-32
Protective Shutdown .............................................................................................2-34Summary .........................................................................................................................2-36
Chapter 3—Electronic Control Unit Operation and Interrogation
Objectives ......................................................................................................................... 3-1 overview ........................................................................................................................... 3-2ECU Interface .................................................................................................................. 3-4ECU Functions ................................................................................................................ 3-6Control Display Unit (CDU) ......................................................................................... 3-8
Current Status Page ...............................................................................................3-10Fault History Page .................................................................................................3-12Maintenance History Page ...................................................................................3-14Input Monitoring Page .........................................................................................3-16IDENT/CONFIG Page ......................................................................................3-18Oil Quantity ............................................................................................................3-20
Summary .........................................................................................................................3-22
Chapter 4—Theory of Operation & Construction
Objectives ......................................................................................................................... 4-1Overview ........................................................................................................................... 4-2Main APU Engine Sections ........................................................................................... 4-4Basic Operating Cycle ..................................................................................................... 4-6Load Compressor Operation ......................................................................................... 4-8Surge Protection ............................................................................................................4-10Generator and Accessories ...........................................................................................4-12APU Temperature Control ..........................................................................................4-14Summary .........................................................................................................................4-16
Chapter 5—Lubrication System
Objectives ......................................................................................................................... 5-1Overview ........................................................................................................................... 5-2Power Section Turbine Bearing Cavity ........................................................................ 5-4
Table of Contents Page iii
131-9B Line Maintenance Training Manual
Forward Bearing and Seal .............................................................................................. 5-6Lubrication System Components ................................................................................. 5-8
Lubrication Module .............................................................................................. 5-10Lube Supply Filter ........................................................................................ 5-12Generator Scavenge Filter ........................................................................... 5-12High Oil Temperature Sensor .................................................................... 5-14
Oil Cooler ............................................................................................................... 5-16Gearbox / Oil Sump ............................................................................................ 5-18Low Oil Quantity Switch ..................................................................................... 5-20Magnetic Chip Collector and Drain Plug .......................................................... 5-22Temperature Control Valve ................................................................................. 5-24Low Oil Pressure (LOP) Switch ......................................................................... 5-26Air-Oil Separator ................................................................................................... 5-28
Oil Servicing Provisions ............................................................................................... 5-30Lubrication System Flow ............................................................................................. 5-32Summary ......................................................................................................................... 5-34
Chapter 6— Fuel System
Objectives ......................................................................................................................... 6-1Fuel System Overview .................................................................................................... 6-2Fuel System Components .............................................................................................. 6-4
Fuel Control Unit (FCU) ....................................................................................... 6-6Fuel Filters ............................................................................................................. 6-10Fuel Metering Assembly ...................................................................................... 6-12fuel Flow Divider & flow divider solenoid ....................................................... 6-14Fuel Manifolds & Fuel Nozzles .......................................................................... 6-16Fuel Shutoff Solenoid ........................................................................................... 6-18IGV Actuator Pressure Regulating Valve ......................................................... 6-20Plenum Drain Valve ............................................................................................. 6-22APU Drain Manifold ............................................................................................ 6-24
Fuel System Flow ...........................................................................................................6-26Summary .........................................................................................................................6-28
Chapter 7—Pneumatic System
Objectives ......................................................................................................................... 7-1Overview ........................................................................................................................... 7-2Pneumatic System Components .................................................................................... 7-4
Surge Control Valve (SCV) .................................................................................... 7-6Flow Sensor Assembly ............................................................................................ 7-8Inlet Temperature Sensor (T2) ............................................................................7-12Bleed Air Valve (BAV) .........................................................................................7-14
Inlet Guide Vane (IGV) Assembly .............................................................................7-16Summary .........................................................................................................................7-18
Chapter 8—Electrical Accessories
Objectives ......................................................................................................................... 8-1Overview ........................................................................................................................... 8-2Electrical Accessories Components .............................................................................. 8-4
Start Power Unit (SPU) .......................................................................................... 8-6Start Converter Unit (SCU) ................................................................................... 8-8Starter-Generator ...................................................................................................8-12Ignition Unit ...........................................................................................................8-14EGT Thermocouples ............................................................................................8-16Speed Sensor ..........................................................................................................8-18Data Memory Module (DMM) ............................................................................8-20
Summary .........................................................................................................................8-22
Chapter 9—Glossary
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131-9B Line Maintenance Training Manual
CHAPTER 1—INTRODUCTION AND
DESCRIPTION
OBJECTIVES
Upon completion of this chapter, you will be able to:• List the main functions of the 131-9B APU• Show the location of the APU line replaceable units (LRU)• Describe the operating specifications and operating
envelope for the APU
Introduction and Description Objec
Notes:
tives Page 1-1
131-9B Line Maintenance Training Manual
OVERVIEW
The 131-9B APU is a self-contained power unit used in the Boeing737-600/-700/-800 airplanes. It is designed to function as a com-bination shaft and pneumatic power source. The APU is controlledby a system of electronic, hydraulic, and electro-mechanical con-trols. Power output is ready for use while the airplane is on theground or in the air.
The APU provides the 737-600/-700/-800 airplane with:- Pneumatic power for airplane main engine starting
(MES)- Pneumatic power for cabin air conditioning (up to
17,000 feet altitude.)- Electric power up to 41,000 feet for the airplane
The APU is comprised of three major sections:- Gearbox- Load Compressor- Power Section
GearboxThe accessory gearbox provides gear reduction for the high speedtorque of the power section. The gearbox also serves as the oilreservoir. Accessories mounted to the gearbox include the oilcooler, starter/generator, and the oil pump.
Load CompressorThe load compressor section supplies air pressure to the aircraftbleed air manifold. It is mounted on a common shaft with thepower section rotating group and shares a common inlet with thepower section compressor.
Introduction and Description Overv
Power SectionThe power section creates mechanical energy to turn the APU’smain shaft. The power section drives the load compressor andaccessory gearbox, providing a high-pressure ratio, high-power-density design that minimizes weight, volume, and fuel consump-tion. Features are:
• a single-stage, 8:1 pressure-ratio centrifugal compressor, a reverse-flow annular combustor, and a two-stage axial turbine.
• a single main shaft that ties the engine compressor and turbine to the load compressor. The shaft is supported by two bearings, a duplex ball bearing located forward of the L/C impeller and a roller bearing located aft of the second-stage turbine.
• Carbon seals used in the front and rear bearing cavities.• a first-stage turbine stator that is compressor air cooled.
Notes:
iew Page 1-2
ATM717-001131-9B Overview
131-9B Overview
ATM717.00109/02
Introduction and Description Overview Page 1-3
131-9B Line Maintenance Training Manual
LRU LOCATION
RIGHT VIEW
Components include:• Starter Generator• Bleed Air Valve• Inlet Guide Vane Actuator• Surge Control Valve• Ignition Unit• Gearbox Vent Line
Introduction and Description LRU Lo
Notes:
cation Page 1-4
ATM717-089Right Side View
Right Side View
ATM717.08911/02
IgnitionUnit Surge Control
Valve Inlet GuideVane Actuator
Bleed AirValve
Starter/Generator
GearboxVent Line
Introduction and Description LRU Location Page 1-5
131-9B Line Maintenance Training Manual
FORWARD VIEW
Components include:• Air/Oil Separator• Oil Fill Port• Generator Scavenge Filter• Bypass Pressure Differential Switch• Lube Filter• Magnetic Drain Plug
Introduction and Description LRU Lo
Notes:
cation Page 1-6
ATM717-080Forward View
Forward View
Air/OilSeparator
MagneticDrain Plug
Bypass PressureDifferential
Switch
Lube Filter
GeneratorScavenge
Filter
Oil FillPort
ATM717.08009/02
Introduction and Description LRU Location Page 1-7
131-9B Line Maintenance Training Manual
LEFT VIEW
Components include:• Temperature Regulating Valve• Oil Cooler• Ignition Unit• Fuel Flow Divider Solenoid• Data Memory Module• Oil Quantity Switch• Fuel Control Unit
Introduction and Description LRU Lo
Notes:
cation Page 1-8
ATM717-081Left Side View
Left Side View
ATM717.08109/02
Oil Cooler
Ignition Unit
TemperatureRegulating
Valve
Fuel ControlUnit
Oil QuantitySwitch
Data MemoryModule
Fuel FlowDivider Solenoid
Introduction and Description LRU Location Page 1-9
131-9B Line Maintenance Training Manual
OPERATING SPECIFICATIONS
The physical and operational characteristics of the APU are listedbelow. For more data on the specific model, refer to the appropri-ate maintenance manual.
Introduction and Description Operating Sp
Notes:
ecifications Page 1-10
ATM717-075Operating Specifications
Operating Specifications
ATM717.07509/02
Total APU weight:398.2 lbs (180.62 KG) with Generator.
Rated Output Shaft Power: 129 SHP Maximum 90 KVA < 32,000 feet66 KVA < 41,000 feet
Rated Output Shaft Speed: 48,800 RPM (100%)
Maximum Turbine EGT:
1175°F (635°C) at sea level
Maximum Allowable Speed: 51,728 RPM (106%)
Maximum Oil Consumption Rate: 8cc/hour
Oil Pressure Limits: 67.5±7.5 psig (466±52 KPA)
Oil Capacity: 8.7 quarts (8.3 ltrs).
Oil "ADD"message:2.5 quarts from full
Oil Quantity to LOP shutdown:4.5 quarts from full
Frequency of Oil ChangeNo oil change required
Frequency of Oil Filter ChangeAt Filter Delta-P Indication
Oil Type:MIL-L-23699 Type IIMIL-L-7808 Type ISee Maintenance Manual for specific brands
Fuel Inlet Pressure:
Fuel Filter Replacement:
APU Supply Power Unit (SPU):
APU Start Converter Unit (SCU):
ECU Power Supply:
10 psig
3500 hours or 3 years
28 vdc/500 amps200 va, 3 phase, 400Hz, 30 amps. max.
28 vdc, 8 amps max
28 vdc, 8 amps max
Introduction and Description Operating Specifications Page 1-11
131-9B Line Maintenance Training Manual
APU DESIGN AND FUNCTION
The 131-9B APU is designed for ground and airborne operation.This makes it possible to use remote airfields that may not haveground power.
The APU provides the 737-600/-700/-800 airplane with:• pneumatic power for airplane main engine starting (MES).• pneumatic power for cabin air conditioning (up to 17,000
feet altitude.)• electric power up to 41,000 feet
The APU is temperature limited. If loads on the APU becomeexcessive (resulting in high EGT), “load shedding” is accom-plished. The ECB automatically cuts back the electric or pneu-matic output, depending on aircraft mode.
NOTE: Electrical power (#1 priority) can be provided independently of, or in combination with pneumatic power.
Introduction and Description APU Design a
Notes:
nd Function Page 1-12
ATM717-006APU Design & Function
APU Design & Function
ATM717.00609/02
WingAnti-IceValve
PressureTransducer
IsolationValve
PneumaticGround Service
Connection
CheckValve
HighStageValveAPU
BleedValve
ReliefValve
R PackValveL Pack
Valve
CheckValve
PressureRegulator
and ShutoffValve
Precooler
PrecoolerControlValve
S
S
S
S
M
M
M
S
Introduction and Description APU Design and Function Page 1-13
131-9B Line Maintenance Training Manual
OPERATING ENVELOPE
The APU is designed to meet the following Boeing requirements:• Starting is allowed up to 41,000 feet. • Bleed and shaft power combination up to 17,000 feet
(5,183 meters). • Electrical power up to 41,000 feet (12,500 meters). • 90 KVA up to 32,000 feet (10,366 meters)• 66 KVA up to 41,000 feet (12,500 meters.)
NOTE: The limiting parameters are governed by ambient temperature and pressure altitude.
Introduction and Description Operating
Notes:
Envelope Page 1-14
ATM717-008Operating Envelope
0
Operating Envelope
ATM717.00809/02
- Electrical up to 41K - 90 KVA up to 32K - 66 KVA up to 41K
- Inflight Starting up to 41K
41,000A
ltit
ud
e x
1,00
0 (F
eet)
17,000
0
Inlet Temperature (F˚)-65 10 75 130
Combination:Bleed & Shaft loads up to17K
Introduction and Description Operating Envelope Page 1-15
131-9B Line Maintenance Training Manual
SUMMARY
Now that you have completed this section, you should be able to:
• List the main functions of the 131-9B APU.• Show the location of the APU line replaceable units (LRU)• Describe the operating specifications and operating
envelope for the APU
To make certain, ask yourself the following questions:
What are the functions of the APU?The 131-9B provides:
• pneumatic power for airplane main engine starting (MES).• pneumatic power for cabin air conditioning (up to 17,000
feet altitude.)• electric power up to 41,000 feet
Where is each LRU located?Refer to the engine views located in this chapter.
What are the operating specifications for the APU?The physical and operational characteristics of the 131-9B arelisted in this chapter. The data reflected is general in nature andmust be considered such. Refer to the maintenance manual.
What is the operating envelope for the APU?The operating limiting parameters are governed by the ambienttemperature and pressure altitude.
• Starting is allowed up to 41,000 feet• Bleed and shaft power combination up to 17,000 feet
(5,183 meters)• Electrical power up to 41,000 feet (12,500 meters)
Introduction and Description Summ
• 90 KVA up to 32,000 feet (10,366 meters)• 66 KVA up to 41,000 feet (12,500 meters)
Notes:
ary Page 1-16
131-9B Line Maintenance Training Manual
CHAPTER 2—INSTALLATION AND INTERFACE
OBJECTIVES
Upon completion of this chapter, you will be able to:• Explain the installation of the APU.• Explain the location of purpose of each APU interface
component (ECU and related panels) that control the APU.• Explain the conditions for Ready-to-Load, Duct
Pressurization Mode, Environmental Control System Mode, and Main Engine Start.
• Explain the start sequence of events for the APU.• Explain the normal shutdown sequence of events.• Explain the conditions that would cause a protection
shutdown.
Installation and Interface Objec
Notes:
tives Page 2-1
131-9B Line Maintenance Training Manual
OVERVIEW
The APU installation provides mounting, line replacement unit(LRU) component accessibility, inlet and exhaust passages, enclo-sure cooling, oil cooling, drainage, bleed air extraction and fireprotection.
Installation components include:• Access Door• APU Inlet Door• Eductor Inlet• Exhaust Pipe• Fuel Line• Bleed Air Duct• Fire Detection Loop
Installation and Interface Overv
Notes:
iew Page 2-2
ATM717-009 Overview
Overview
ATM717.00909/02
• Access Door
• APU Inlet Door
• Eductor Inlet
• Exhaust Pipe
• Fuel Line
• Bleed Air Duct
• Fire Detection Loop
Installation and Interface Overview Page 2-3
131-9B Line Maintenance Training Manual
APU LOCATION
The APU is suspended in the tail cone. Access to the APU isthrough a large door beneath the APU. The enclosure providesmounting points, line replaceable unit (LRU) access, and fire pro-tection.
Installation and Interface APU Lo
Notes:
cation Page 2-4
ATM717-090APU Location
ATM-717.09009/02
APU Location
Installation and Interface APU Location Page 2-5
131-9B Line Maintenance Training Manual
APU INSTALLATION
LocationLocationThe APU is mounted in a fireproof compartment located in the aftend of the fuselage.
Access DoorsThe APU access door on the bottom of the APU compartment per-mits servicing and maintenance. Releasing three latches on theleft side opens the access door to the right on two hinges. A rodholds the door open safely.
Mount StrutsThe APU is mounted with support struts. That provide vertical andhorizontal stability and vibration isolation.
APU Removal/InstallationFish poles are used to remove the APU. The fish poles areattached to the top of the APU compartment with fish pole cablesattached to the APU. The weight of the APU is held up by the fishpole while the APU struts are disconnected. Once the APU strutsare removed, the APU is lowered by slowly releasing the fish polecables.
APU Inlet AirAir supply to the APU is through an aircraft mounted inlet doorand plenum chamber.
Fire DetectionThe fire loop is attached to the airframe. This loop detects a firecondition and sends the information to the aircraft fire warningsystem. The aircraft system reports this condition to the APU ECUfor immediate shutdown.
Installation and Interface APU Inst
DrainsThe APU has a drain manifold consisting of a forward, middle, aftdrain. This system provides a means for draining fluid overboard.
NOTE: The fire loop assembly does not have to be removed prior to APU removal.
Notes:
allation Page 2-6
ATM717-104APU Installation
APU Installation
ATM717.10409/02
EXHAUST MIXED FLOW
Inlet Air
Inlet VortexGenerator
APU AirOutput
APU Compartment
Eductor Inlet(cooling air)
FCU
SCV
Gen.BAV
OilCooler
Fuel TankFuel Pump
APU SOVExhaust
Pipe
APU Compartment
Door Latches
APU InletDoor
Inlet Door Actuator& Position Switch
Installation and Interface APU Installation Page 2-7
131-9B Line Maintenance Training Manual
APU DRAIN MANIFOLD
The drain manifold consisting of a forward, middle, aft drain. toallow for the draining of fluid overboard.
The forward drain is used for detecting degraded seal perfor-mance in the:
• fuel control,• inlet guide vane actuator, and• surge control valve.
The middle drain is used for detecting degraded seal performancein the load compressor main shaft seal.
The aft drain is used for disposing of excess fuel in the event of anaborted start and also a means of draining the aircraft exhaustmuffler. During normal APU operation, no fuel is discharged fromthe aft drain.
The leakage limits shown are acceptable after 5 minutes of opera-tion.
NOTE: The APU inlet plenum has a drain which flows into the APU compartment.
Table 2-1:
Fuel Control Leakage Limits 3 drops per minute
Inlet Guide VAne Actuator 3 drops per minute
Surge Control Valve 3 drops per minute
Oil Consumption 8 cc per hour
Installation and Interface APU Inst
Notes:
allation Page 2-8
ATM717-020APU Drain Manifold
APU Drain Manifold
ATM717.02009/02
Gearbox Vent
InletGuide Vane
Actuator
Tell-TalePort
Tell-TalePort
Load CompressorSeal Drain
Combustor Case,Edustor Muffler,
& Drain Mast
LubeModule
FuelControl
Gearbox
SurgeControlValve
CheckValve
AirFlow
Starter/Generator
Fuel Control, Surge Control Valve,& Inlet Guide Vane Actuator
Installation and Interface APU Installation Page 2-9
131-9B Line Maintenance Training Manual
AIRCRAFT CONTROL/DISPLAY INTERFACE
The APU control system consists of the Electronic Control Unit(primary control) along with other airplane panels located in thecockpit. The APU control system consists of the following:
• Full Authority Digital Electronic Controls (ECU)• APU Master Switch (APU and main engine control)• APU Bleed Valve Switch (air conditioning and pneumatics)• APU Generator Switches (electrical controls)• APU Remote Control Panel (fire protection panel -
external)• APU Fire Handle Switch (external)• APU Indication Panel
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-10
ATM717-011Aircraft Control & Displays
HORNCUTOUT
BOTTLEDISCHARGE
1. PULL HANDLE DOWN
2. DISCHARGE BOTTLE
APUFIRE
CONTROL
APU Master Switch(P5-4)
APU Fire HandleSwitch (P8-1)
M1709 Electronic Control Unit(Aft Cargo Compartment)
APU Generator Switches(P5-3)
APU
OFF
ON
OFF
ON
OFF
ON1 2
OFF
ONAPU
BLEED
APU GEN
APU GENOFF BUS
OFF
ON
START
APU Bleed Valve Switch(P5-10)
APU Remote ControlPanel (P28) Right
Wheel Well
DISCH
Aircraft Control & Displays
ATM717.01109/02
Installation and Interface Aircraft Control/Display Interface Page 2-11
131-9B Line Maintenance Training Manual
ELECTRONIC CONTROL UNIT
Identification and LocationThe ECU is a full-authority, digital electronic control, located inthe aft cargo compartment, next to the aft cargo door.
Purpose and InterfaceThe ECU functions include:
• Pre-Start Built-In-Test-Equipment• Automatic Start Control• Speed Control within 1 percent rpm• Protective Shutdown capability• Start Inhibit capability• Fault storage• Fault reporting to the Control Display Unit (CDU)
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-12
ATM717-010Electronic Control Unit (ECU)
Electronic Control Unit (ECU)
ATM717.01009/02
Electronic Control Unit(Aft Cargo Compartment)
Installation and Interface Aircraft Control/Display Interface Page 2-13
131-9B Line Maintenance Training Manual
APU MASTER SWITCH
Identification and LocationThe APU master switch is located on the overhead panel (P5-4). Itcontains a start switch.
Purpose and InterfaceThe APU master switch:
• initiates APU Start and Stop sequences• controls the airplane inlet door,• controls the fuel boost pump (optional), • controls the APU fuel valve
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-14
ATM717-091APU Master Switch
APU Master Switch(P5-4)
APU
OFF
ON
START
APU Master Switch
ATM717.09109/02
Installation and Interface Aircraft Control/Display Interface Page 2-15
131-9B Line Maintenance Training Manual
APU INDICATION PANEL
Identification and LocationThe APU indication panel is located on the overhead panel (P5-4).
Purpose and InterfaceThe APU indication panel has four lights to indicate a problem tothe operator for the following:
• maintenance• low oil pressure• fault• overspeed
The panel also has an EGT indicator for APU temperature read-ings.
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-16
ATM717-096APU Indication Panel
P5-4 PANEL
LOW
HIGH
INT
L WIPERPARK10
EGT8
6
4 2
FAULT OVERSPEED
LOW OILPRESSUREMAINT
APU Indication Panel
ATM717.09609/02
Installation and Interface Aircraft Control/Display Interface Page 2-17
131-9B Line Maintenance Training Manual
APU BLEED VALVE SWITCH
Identification and LocationThe APU bleed valve switch is located on the overhead panel (P5-10). It is a two position switch; OFF and ON.
Purpose and InterfaceThe bleed valve switch provides a signal to the ECU. The ECUenergizes the APU bleed valve solenoid to open the bleed valve.
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-18
ATM717-092APU Bleed Valve Switch
OFF
ON1 2
OFF
ONAPU
BLEED
APU Bleed Valve Switch(P5-10)
APU Bleed Valve Switch
ATM717.09209/02
Installation and Interface Aircraft Control/Display Interface Page 2-19
131-9B Line Maintenance Training Manual
APU GENERATOR SWITCHES
Identification and LocationThe APU generator switches are located on the overhead panel(P5-3).
Purpose and InterfaceThe APU generator switches give manual control for APU genera-tor power source selection. There are two switches because thereare two bus tie breakers (BTBs).
The blue APU GEN OFF Bus Light comes on when the APU is readyto supply electrical power.
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-20
ATM717-093APU Generator Switches
APU Generator Switches(P5-3)
OFF
ON APU GEN
APU GENOFF BUS
OFF
ON
APU Generator Switches
ATM717.09309/02
Installation and Interface Aircraft Control/Display Interface Page 2-21
131-9B Line Maintenance Training Manual
APU GROUND CONTROL PANEL
Identification and LocationThe APU ground control panel (P28) and Fire Alarm Horn arelocated in the right wheel well, on the AFT bulkhead.
Purpose and InterfaceThe APU ground control panel allows the operator to stop the APUfrom outside the airplane.
• Pull the handle down to shut down the APU and arm the fire bottle discharge switch.
• Push the toggle switch to discharge the APU fire bottle.
APU fire alarm causes the following to occur:• The APU fire warning light to flash.• The APU fire warning horn to sound (on ground only).
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-22
ATM717-094APU Ground Control Panel
HORNCUTOUT
BOTTLEDISCHARGE
1. PULL HANDLE DOWN
2. DISCHARGE BOTTLE
APUFIRE
CONTROL
APU Remote ControlPanel (P28) Right
Wheel Well
APU Ground Control Panel
ATM717.09409/02
Installation and Interface Aircraft Control/Display Interface Page 2-23
131-9B Line Maintenance Training Manual
APU FIRE HANDLE SWITCH
Identification and LocationThe APU fire handle switch is located on the electronic controlpanel (P8).
Purpose and InterfaceThe APU fire handle switch allows the operator to discharge theAPU fire bottle.
APU fire alarms cause the following to occur:• Automatic APU shutdown• The master fire warning lights come on.• The APU fire switch light comes on.• The APU fire switch unlocks.• The flight deck fire bell rings.
Lifting and turning the fire handle will discharge the fire bottle.
Installation and Interface Aircraft Control/D
Notes:
isplay Interface Page 2-24
ATM717-095APU Fire Handle Switch
APU Fire HandleSwitch (P8-1)
DISCH
APU Fire Handle Switch
ATM717.09509/02
Installation and Interface Aircraft Control/Display Interface Page 2-25
131-9B Line Maintenance Training Manual
APU START SEQUENCE
You can start the APU up to an altitude of 41,000 feet (12,500meters). The ECU controls the following components during start:
• APU inlet door• APU fuel shutoff valve• APU fuel • Ignition• APU start system
Pre-start• The battery switch must be on before you can start and
operate the APU.• If AC power is available, turn the aft number 1 fuel boost
pump on. This gives pressurized fuel to the APU. Pressurized fuel makes the APU start better.
APU Start Sequence• Move the APU master switch to the START position and
release it. The switch moves back to the ON position. Sending a signal to the ECU.
• The ECU opens the APU fuel shut-off valve and the APU inlet door. When the air inlet door is fully open, the door switch closes. The door switch sends a “door fully open” signal to the ECU.
• 0% speed, the ECU energizes the starter-generator and ignition circuit.
• 7% speed, the fuel solenoid valve opens. • 34% speed, the low oil pressure light (P5) goes out.• 60% speed, the ignition unit de-energizes• 70% speed, the starter-generator de-energizes
Installation and Interface APU Start
• 95% + 2 seconds, the APU can supply electrical and pneumatic power.
• 100% speed, full speed- >106%, overspeed shutdown is initiated.
NOTE: Maximum altitude for shaft loading is 41,000 feet and pneumatic loading is 17,000 feet.
Notes:
Sequence Page 2-26
ATM717-012APU Start Sequence
APU
OFF
START
ON
Maximum speed
APU Switch (P5)
- Battery Switch "ON"- APU Switch to the "Start" Position & Release t o"ON"- APU Fuel SOV open Air Inlet Door open- Starter/Generator Energized
1 0 0 %9 5 %
7 0 %
6 0 %
3 4 %
7 %
0 %
6 0 S e c o n d s t a r t t i m e t o 1 0 0 %
100% Governed speedElectrical & PneumaticLoading are Available
Starter/Generator de-energized
Ignition unit de-energized
Low Oil Pressure light "off"
Fuel solenoid valve opens
Ignition unit energized
1 0 6 %
APU Start Sequence
ATM717.01209/02
Installation and Interface APU Start Sequence Page 2-27
131-9B Line Maintenance Training Manual
READY TO LOAD (RTL)
In the Ready to Load mode of operation, the conditions are:• Speed >95% plus 2 seconds• Bleed Air switch is OFF.
At 95% +2 seconds, the ECU sends the APU Ready-to-Load (RTL)signal to the aircraft which indicates that the generator and pneu-matic power are available.
NOTE: It should be noted that Boeing recommends 2 minute warm up before loading the APU. This allows the internal temperature to stabilize.
NOTE: The Surge Control Valve (SCV) is modulating open and Generator loading is available.
Installation and Interface APU Start
DUCT PRESSURIZATION MODE
In the Duct Pressurization mode of operation, the conditions are:• Speed >95% plus 2 seconds• Bleed Air switch ON• LMES, RMES, LECS and RECS signals are false• Altitude <17,000 feet
The IGVs are set as a function of P2 to provide at least 10 psigbleed pressure to the aircraft.
Notes:
Sequence Page 2-28
ATM717-070Ready-to-Load (RTL)
• Speed is >95 plus 2 seconds
• Bleed Air Switch in "OFF"
Duct Pressurization Mode
• Speed is >95 plus 2 seconds
• Bleed Air Switch in "ON"
• LMES, RMES, LECS, & RECS signals are false
• Altitude <17,000 feet
Ready-to-Load (RTL)
ATM717.07009/02
Installation and Interface APU Start Sequence Page 2-29
131-9B Line Maintenance Training Manual
ENVIRONMENTAL CONTROL SYSTEM MODE (ECS)
In the Environmental Control System (ECS) mode, the conditionsare:
• Speed is >95% plus 2 seconds. • Bleed Air Switch ON.• LMES and RMES signals are false.• LECS and RECS signal signals (2 pack) are true• Altitude <17,000 feet
When the left or right ECS packs are set to “ON”, the ECU sets theAPU IGVs to a pre-determined position.
MAIN ENGINE START (MES)
MES mode of operation conditions are met when:• Speed >95% plus 2 seconds.• Bleed air switch is ON• Either LMES or RMES is true• Altitude <17,000 feet
When the left or right MES switches are set to “ON”, the IGVs areset at 90° (full open) and the surge control system is active (fullyclosed).
The inlet guide vane (IGV) maximum position will vary duringMES mode. The IGV positions are determined by using inlet tem-perature. The MES positions are:
• 68° / -65°F• 71° / -40°F
Installation and Interface APU Start
• 75° / 0.0°F• 82° / 30°F• 90° / 90°F• 90° / 130°F
NOTE: In MES mode, the pneumatic power has priority over electrical. If the APU EGT trim limit is obtained, the APU electrical load is reduced to prevent an overtemperature condition.
Notes:
Sequence Page 2-30
ATM717-072Environmental Control System Mode
(ECS)
Environmental Control System Mode (ECS)
ATM717.07209/02
Main Engine Start (MES)
• Speed is >95 plus 2 seconds
• Bleed Air Switch in "ON"
• LMES or RMES signals are true
• Altitude <17,000 feet
• Speed is >95 plus 2 seconds
• Bleed Air Switch in "ON"
• LMES and RMES signals are false
• LECS and RECS signals (2 pack) are true
• Altitude <17,000 feet
Installation and Interface APU Start Sequence Page 2-31
131-9B Line Maintenance Training Manual
APU SHUTDOWN
The ECU controls the APU shutdown. Their are two types of shut-down conditions, normal and protective.
NORMAL SHUTDOWN
The normal shutdown sequence is as follows:• APU switch placed to ‘OFF’ position
- 28 vdc ON signal removed from ECU- ECU receives the OFF signal- RTL signal is removed- 60 second cool-down period starts
• At 30% speed, the APU air inlet door starts to close (closes immediately for APU fire).
• At less than 7% speed, an APU restart can be initiated.
Cool Down CycleThe cool down period prevents oil coke at the turbine bearing andfuel nozzles. During cool down, the ECU:
• Removes the ready-to-load signal• Closes the bleed air valve• Closes the inlet guide vanes (22 degrees)• Opens the surge control valve• De-energizes the starter generator• Starts the 60 second timer
Installation and Interface APU Shu
NOTE: The APU fuel shutoff valve and air inlet door close for both the normal and protective shutdown.
NOTE: A protective shutdown has no cool down cycle.
CAUTION: DO NOT USE A BATTERY SWITCH OR FIRE SWITCH TO BEGIN A NORMAL APU SHUTDOWN. IF THE FUEL SHUTOFF VALVE DOES NOT CLOSE IN THE REQUIRED TIME, THE APU FAULT LIGHT WILL COME ON AND STAY ON UNTIL THE APU IS STARTED AGAIN OR THE BATTERY SWITCH IS PUT IN THE OFF POSITION.
Notes:
tdown Page 2-32
ATM717-013APU Normal Shutdown Sequence
OFF
ON
START
100%
APU Operating
30%
7%
0%
APU fuel shutoff valveand inlet door start to close
An APU restart can beinitiated
APU switch placed to "Off"- 28 vdc "ON" signal removed from ECU- ECU recieves the "OFF" signal- The Ready-to-load signal is removed- 60 second cool-down period starts
60 second cool down
APU Normal Shutdown Sequence
ATM717.01309/02
Installation and Interface APU Shutdown Page 2-33
131-9B Line Maintenance Training Manual
PROTECTIVE SHUTDOWN
The hardware and software circuits inside the ECU control auto-matic protective shutdowns of the APU. The cause for a protectiveshutdown displays on the CDU located on the P9 panel.
Protective Shutdowns: (Fault Light ON)• APU fire • Fuel shutoff valve not in commanded position• Critical ECU failure • High oil temperature• Inlet door not in commanded position• Loss of DC power • Loss of both EGT signals• No acceleration• No flame• No speed signal • Sensor Failure• Overtemperature • Reverse flow (load compressor)• Under speed• APU inlet overheat• Generator filter clogged.
Overspeed Light ON• Fuel control unit solenoid failure• Loss of overspeed protection• Overspeed of more than 106% rpm
Low Oil Pressure Light ON• Low oil pressure
Installation and Interface APU Shu
Maintenance Light ON• Failed oil quantity switch• Low oil quantity• Start generator shorted rotating diode
Notes:
tdown Page 2-34
ATM717-065Protective Shutdowns
- APU FIRE *- FUEL SOV NOT IN COMMAND POSITION- CRITICAL ECU FAILURE *- HIGH OIL TEMPERATURE- INLET DOOR NOT IN COMMAND POSITION *- LOSS OF DC POWER- LOSS OF EGT SENSING - BOTH SIGNALS *- NO ACCELERATION- NO FLAME- NO SPEED SIGNAL- OVERTEMPERATURE- REVERSE FLOW (LOAD COMPRESSOR)- UNDERSPEED- APU INLET OVERHEAT- GENERATOR FILTER CLOGGED
- LOW OIL PRESSURE
- FUEL CONTROL UNIT SOLENOID FAILURE - LOSS OF OVERSPEED PROTECTION - OVERSPEED OF MORE THAN 106% RPM
- FAULT OF OIL QUANTITY SWITCH- LOW OIL QUANTITY- START/GEN. SHORTED ROTATING DIODE
FAULT OVERSPEED
MAINT
LOW OILPRESS
FAULTOVER
SPEEDMAINT LOW OILPRESS APU INDICATOR PANEL (P5)
* Start inhibit- Sensor Failure
Protective Shutdowns
ATM717.06509/02
Installation and Interface APU Shutdown Page 2-35
131-9B Line Maintenance Training Manual
SUMMARY
Now that you have completed this section, you should be able to:
• Explain the installation of the APU.• Explain the location of purpose of each APU interface
component (ECU and related panels) that control the APU.• Explain the conditions for Ready-to-Load, Duct
Pressurization Mode, Environmental Control System Mode, and Main Engine Start.
• Explain the start sequence of events for the APU.• Explain the normal shutdown sequence of events.• Explain the conditions that would cause a protection
shutdown.
Describe the APU installation.• The APU access door on the bottom of the APU
compartment permits servicing and maintenance. • The APU is mounted with support struts. That provide
vertical and horizontal stability and vibration isolation.• Fish poles are used to remove the APU. • Air supply to the APU is through an aircraft mounted inlet
door and plenum chamber. • The fire loop is attached to the airframe provides for fire
protection. • A drain manifold consisting of a forward, middle, aft drain.
provides a means for draining fluid overboard.
What is the location and purpose of the ECU and panels that control the APU?
• ECU - a full-authority, digital electronic control, located in the aft cargo compartment, next to the aft cargo door.
Installation and Interface Summ
• APU Master Switch - is located on the overhead panel (P5-4). The APU master switch initiates APU Start and Stop sequences, controls the airplane inlet door, controls the fuel boost pump (optional), and controls the APU fuel valve.
• APU Indication Panel - located on the overhead panel (P5-4). It has four lights to indicate a problem to the operator for maintenance, low oil pressure, fault and overspeed.
• APU Bleed Valve Switch - located on the overhead panel (P5-10). It contains a two position switch; Off & On.
• APU Generator Switches - located on the overhead panel (P5-3). The switches give manual control for APU generator power source selection.
• APU Ground Control Panel - located in the right wheel well, on the aft bulkhead, allows the operator to stop the SPU from outside the airplane.
Notes:
ary Page 2-36
• APU Fire Handle Switch - located on the aft electrical panel (P8). It allows the operator to discharge the APU fire bottle.
What are the conditions for the Ready-to-Load, Duct Pressurization, Environmental Control System, and Main Engine Start Modes?
Ready to Load mode:
- Speed >95% plus 2 seconds- Bleed Air switch is OFF.
Duct Pressurization mode:
- Speed >95% plus 2 seconds- Bleed Air switch ON- LMES, RMES, LECS and RECS signals are false- Altitude <17,000 feet
Environmental Control System (ECS) mode:
- Speed is >95% plus 2 seconds. - Bleed Air Switch ON.- LMES and RMES signals are false.- LECS and RECS signal signals (2 pack) are true- Altitude <17,000 feet
MES mode of operation conditions:
- Speed >95% plus 2 seconds.- Bleed air switch is ON- Either LMES or RMES is true- Altitude <17,000 feet
What is the start sequence of events for the APU?• Battery switch ON• APU switch to the Start position • 0% speed, the ECU energizes the starter-generator and
ignition circuit• 7% speed, the fuel solenoid valve opens
Installation and Interface Summ
• 34% speed, the low oil pressure light (P5) goes out• 60% speed, the ignition unit de-energizes• 70% speed, the starter-generator de-energizes• 95% + 2 seconds, the APU can supply electrical and
pneumatic power• 100% speed, full speed
- >106%, overspeed shutdown is initiated
What is the normal shutdown sequence of events? Explain the cooldown cycle.
• APU switch placed to ‘OFF’ position- 28 vdc ON signal removed from ECU- ECU receives the OFF signal- RTL signal is removed- 60 second cool-down period starts
• At 30% speed, the APU air inlet door starts to close (closes immediately for APU fire).
• At less than 7% speed, an APU restart can be initiated.
Notes:
ary Page 2-37
131-9B Line Maintenance Training Manual
During cool down, the ECU:• Removes the ready-to-load signal and closes the bleed air
valve• Closes the inlet guide vanes (22 degrees)• Opens the surge control valve and de-energizes the starter
generator• Starts the 60 second timer
What are the conditions that would cause a protective shutdown?
Protective Shutdowns: (Fault Light ON)• APU fire • Fuel shutoff valve not in commanded position• Critical ECU failure • High oil temperature• Inlet door not in commanded position• Loss of DC power • Loss of both EGT signals• No acceleration; No flame• No speed signal • Oil temperature or inlet air temperature sensor failure
(Need to included in graphic?)• Overtemperature • Reverse flow (load compressor)• Under speed• APU inlet overheat and Generator filter clogged
Overspeed Light ON• Fuel control unit solenoid failure; Loss of overspeed
protection; Overspeed of more than 106% rpm
Installation and Interface Summ
Low Oil Pressure Light ON• Low oil pressure;
Maintenance light ONFailed oil quantity switch; Low oil quantity; Start generatorshorted rotating diode
Notes:
ary Page 2-38
131-9B Line Maintenance Training Manual
CHAPTER 3—ELECTRONIC CONTROL UNIT OPERATION
AND INTERROGATION
OBJECTIVES
After completing classroom discussion, you should be able to:• Identify the inputs and outputs to the ECU.• Explain the main functions of the electronic control unit
(ECU): start sequencing, speed governing, load sequencing, shutdown sequencing.
• Describe the purpose of each APU menu page.
Electronic Control Unit Operation and Interrogation Objec
Notes:
tives Page 3-1
131-9B Line Maintenance Training Manual
OVERVIEW
The 131-9B APU uses a computer based electronic control unit(ECU) designed to control and provide an interface with the air-craft and subsystems.
The ECU incorporates a built-in-test-equipment (BITE) featurethat ensures safe operation of the APU. The ECB interface to theaircraft includes hardware discrete signals and a AeronauticalRadio. Inc. (ARINC) 429 communication system.
Inputs to the ECU are:• ARINC 429 Low-Speed Receiver Environmental Control
System (ECS)• ARINC 429 Low-Speed Receiver Generator Control Unit
(GCU)• ARINC 429 Low-Speed Receiver Central Fault Display
System• Data memory module (DMM)• Line replaceable units (LRU)
Electronic Control Unit Operation and Interrogation overv
Notes:
iew Page 3-2
ATM717-010Electronic Control Unit (ECU)
Electronic Control Unit (ECU)
ATM717.01009/02
Electronic Control Unit(Aft Cargo Compartment)
Electronic Control Unit Operation and Interrogation overview Page 3-3
131-9B Line Maintenance Training Manual
ECU INTERFACE
The ECU input/output diagram shows the discrete and analoginput command signals received by the ECU from the aircraft andthe discrete and analog output signals produced by the ECU.
Input SignalsInput signals represent the commands from the flight deck con-trol panels, ECU essential pin, inlet door switches, and aircraftsensors and switches.
Output SignalsOutput signals are produced by the ECU and are used to controlthe operation of aircraft indicators.
Electronic Control Unit Operation and Interrogation ECU In
Notes:
terface Page 3-4
ATM717-060ECU Interface
LOP SWITCH SPEED SENSOR 2SPEED SENSOR 1
TOTAL PRESSURE SENSORDELTA PRESSURE SENSORBLEED AIR VALVE OPEN CMDBLEED AIR VALVE POSITION SWITCHINLET TEMPERATURE (T2) SENSOR
SCV T/MSCV LVDT PRIMARYLVDT SECONDARY
VA
CONTROL DISPLAYUNIT (CDU)
OIL LEVEL “ADD”OIL LEVEL “LOQ”OIL TEMP SENSORRESOLVER EXC
RESOLVER SINERESOLVER COSINEFCU T/MFUEL SHUTOFF VALVE
FUEL TEMPERATURE
INLET PRESS. (P2 ) SENSORIGV T/MIGV LVDT PRIMARYMA LVDT SECONDARYV
IGNITIONEGT #1 AND #2SCU BITE #1SCU BITE #2SCU BITE #3
SCU BITE #4
PERSONALCOMPUTER
DATA MEMORY MODULE
READY-TO-LOAD (RTL)READY-TO-LOAD (RTL)
APU FUEL S0V/AIR INLET DOOR OPENAPU FUEL SHUTOFF VALVE/AIR INLET DOOR CLOSE
AIR INLET DOOR POSITION SWITCH POWER ELECTRONIC
CONTROL
UNIT
FIRE (COCKPIT)FIRE (REMOTE)
FIRE (AUTOMATIC DETECTORS)
BLEED-AIR-SWITCHAIRPLANE SIGNATURE #1
AIRPLANE SIGNATURE #2AIR/GROUND
L ECS PACK VALVE COMMANDR ECS PACK VALVE COMMAND
LEFT MES COMMANDRIGHT MES COMMAND
ESSENTIAL/NON ESSENTIALAIR INLET DOOR OPEN
AIR INLET DOOR NOT OPEN
OFFON
START
FROMMAIN
BATTERY
LOAD SHED
OFFONSTART
LOP
FAULT
EGT METER
OVERSPEEDMAINTENANCE
ARINC 429
28-VOLT POWER
RS 422
ECU Interface
ATM717.06009/02
Electronic Control Unit Operation and Interrogation ECU Interface Page 3-5
131-9B Line Maintenance Training Manual
ECU FUNCTIONS
The ECU inputs are used to control the following:• Start sequence• Speed governing• Load sequencing• Shutdown sequence
Start SequenceThe APU starts automatically after placing the APU Master switchto “START”. The ECU controls the ignition and fuel automaticallyas required for ambient conditions.
During pre-start Built-In-Test-Equipment (BITE), if a failure isdetected that would critically affect APU operation, the ECU inhib-its starting of the APU until the failure is resolved. The failure isstored in the ECU and the APU FAULT indicator is illuminated onthe APU control panel.
Speed GoverningExhaust gas temperature and engine speed are continuouslymonitored by the ECU. Once on-speed, the ECU maintains enginespeed at 48,800 RPM (±1.0%).
Load SequencingThe ECU regulates the APU pneumatic output by sensing the APUEGT and comparing this to a predetermined schedule within theECU. Bleed extraction is reduced to prevent an overtemperaturecondition.
ShutdownThe ECU shuts down the APU if engine speed exceeds 106% orEGT exceeds 1175F (635C).
Electronic Control Unit Operation and Interrogation ECU Fu
The ECU has the authority to shut down the APU when BITE indi-cates that continued APU operation might cause damage. Uponrequest, the ECU reports all APU fault data to the CDU. Thisallows troubleshooting of APU fault data.
Notes:
nctions Page 3-6
ATM717-069ECU Functions
• Pre-Start Built-In-Test-Equipment
• Automatic Start Control
• Speed Control within 1 percent rpm
• Protective Shutdown capability
• Start Inhibit capability
• Fault storage
• Fault reporting to the Control Display Unit (CDU)
ECU Functions
ATM717.06909/02
Electronic Control Unit Operation and Interrogation ECU Functions Page 3-7
131-9B Line Maintenance Training Manual
CONTROL DISPLAY UNIT (CDU)
The APU indicating data can be viewed on the Control Display Unit(CDU), of which there are two (2) on the forward electronicspanel of the cockpit, if 115v ac power is available on the aircraft.
Accessing CDU Information • On IDENT page, push line select key 6L (INDEX). The
INIT/REF/INDEX page displays.• Press key 6R (MAINT) and the MAINT BITE INDEX page
displays.• Press key 2R (APU) and the APU BITE MAIN MENU page
displays.
Selecting the APU Menu PagesFrom the APU BITE TEST MAIN MENU you can select one of sixAPU menu pages:
• Current status: shows currently active maintenance faults• Fault history: shows faults that cause the APU to shutdown
or abort a start.• Maintenance history: shows faults that turn on the MAINT
light on the P5 panel and faults that have no flight compartment indication.
• Ident/Config (DMM data included): shows APU serial number, hours of operation, number of starts, ECU part and serial number, ECU software version.
• Input monitoring: shows APU operating parameters to assist in fault isolation.
• Oil quantity: shows the APU oil level as either FULL, LOW or ADD.
Electronic Control Unit Operation and Interrogation Control Displa
Returning to the Main MenuPush the INDEX button to return to the Main Menu page from anyof the APU menu pages.
Notes:
y Unit (CDU) Page 3-8
ATM717-051Control Display Unit
1 2
3
Select: APU > Main Menu page
Select: MAINT >Select: < INDEX
MAINTENANCE HISTORY >
< CURRENT STATUS
APU BITE TESTMAIN MENU
1/1
< FAULT HISTORY
< IDENT/CONFIG
< INPUT MONITORING
< INDEX OIL QUANTITY >FMC DOWN LOAD >
APU >
FQIS >
ENGINES >
< INDEX
< CDS
< ADIRS
< A/T
< DFCS
< FMCS
MAINT BITE INDEX 1/1
< INDEX MAINT >
IRS NAV >
ALTN DEST >
NAV DATA >
< OFFSET
< APPROACH
< TAKE OFF
< PERF
< POS
< IDENT
INT / REF INDEX 1/1
737-700NAV DATAUAL 6820401
MODEL
OP PROGRAM548849-001
MAR18APR17/97APR18MAY17/97
SUPP DATA APR 17/97
ENG RATING18.5K
ACTIVE
IDENT 1/2
POS INIT >
MSG RECALL >
Control Display Unit (CDU)
ATM717.05109/02
Electronic Control Unit Operation and Interrogation Control Display Unit (CDU) Page 3-9
131-9B Line Maintenance Training Manual
CURRENT STATUS PAGE
PurposeThe Current Status page displays currently active APU mainte-nance faults.
DescriptionThere are approximately 200 different APU faults. When the APUECU detects a maintenance fault, the active fault is stored in theECU memory. Each fault has an assigned maintenance messagecode. The maintenance message code is used with the Boeingmaintenance manual for corrective actions.
Electronic Control Unit Operation and Interrogation Control Displa
Notes:
y Unit (CDU) Page 3-10
ATM717-052Current Status Page
B
A
12
3
Displayed i f noother occurrenceshave happened
CURRENT STATUSUNKNOWN FLT DECK EFFECT MAINT MSG 49-71146EGT 1 THERMOCOUPLEDISAGREE WITH EGT 2
NO OTHER OCCURRENCES
A P U B I T E T E S T
CURRENT STATUSUNKNOWN FLT DECK EFFECT MAINT MSG 49-71146EGT 1 THERMOCOUPLEDISAGREE WITH EGT 2OTHER OCCURRENCES/STARTS1 2 11 31 99 200456 801 999
A P U B I T E T E S T 1 / 1
CURRENT STATUSUNKNOWN FLT DECK EFFECT MAINT MSG 49-71146EGT 1 THERMOCOUPLEDISAGREE WITH EGT 2RUN APU AND SELECT BLEEDAIR TO CONFIRM REPAIR
APU >
FQIS >
< INDEX
< CDS
< ADIRS
< A/T
< DFCS
< FMCS
MAINT BITE INDEX 1/1
MAINTENANCE HISTORY >
OIL QUANTITY >
< CURRENT STATUS
< FAULT HISTORY
< IDENT/CONFIG
< INPUT MONITORING
< INDEX
APU BITE TESTMAIN MENU
1/1
< INDEX
FMC DOWN LOAD >
ENGINES >
OCCURRENCES >OTHER
< INDEX
< INDEX
Displayed i f otheroccurrenceshave happened
Press to seeAPU menuscreen
Press to seeCurrent Statusscreen
Press forOther Occurrencesscreen
Select APU
Current Status Page
Current Status Interrogation
Current Status Page
ATM717.05209/02
Electronic Control Unit Operation and Interrogation Control Display Unit (CDU) Page 3-11
131-9B Line Maintenance Training Manual
FAULT HISTORY PAGE
PurposeThe Fault History page displays faults that cause the APU to shut-down.
DescriptionOne fault displays per page. Each fault has an assigned mainte-nance message code. The maintenance message code is usedwith the Boeing maintenance manual for corrective actions.
A maximum of 99 shutdowns can be stored in Fault History. Toview the faults, push the NEXT PAGE button on the CDU.
Electronic Control Unit Operation and Interrogation Control Displa
Notes:
y Unit (CDU) Page 3-12
ATM717-053Fault History Page
1
2
A P U B I T E T E S T 1 / 1 1 A P U B I T E T E S T 2/ 1 1
< FAULT HISTORY FAULT LIGHT MAINT MSG 49-71146 EGT 1 THERMOCOUPLE MAINT MSG 49-71146 EGT 2 THERMOCOUPLE LOSS OF EGT SHUTDOWN DATE GMT STARTS OLD APR 10 1027 11
MAINTENANCE HISTORY >
OIL QUANTITY >
< CURRENT STATUS
< FAULT HISTORY
< IDENT/CONFIG
< INPUT MONITORING
< INDEX
APU BITE TESTMAIN MENU
1/1
CURRENT STATUS >
OTHER OCCURENCES >
< FAULT HISTORY FAULT LIGHT MAINT MSG 49-41011 SEE FAULT ISOLATION MANUAL NO FLAME SHUTDOWN DATE GMT STARTS OLD APR 13 1149 1
CURRENT STATUS >
OTHER OCCURENCES >
Main Menu Page
Fault History Page 1 of 11 Fault History Page 2 of 11
NOTE:To move between pages,use the PREV/NEXT keyon the CDU
Press to ViewFault HistoryScreen/Displays
Fault History Page
ATM717.05309/02
Electronic Control Unit Operation and Interrogation Control Display Unit (CDU) Page 3-13
131-9B Line Maintenance Training Manual
MAINTENANCE HISTORY PAGE
PurposeThis Maintenance History page displays faults that either
• turn on the MAINT light located on the APU panel, or• have no flight deck indication.
DescriptionOne fault displays per page. To view additional faults, push theNEXT PAGE button on the CDU. Each fault has an assigned main-tenance message code. The maintenance message code is usedwith the Boeing maintenance manual for corrective actions.
Electronic Control Unit Operation and Interrogation Control Displa
Notes:
y Unit (CDU) Page 3-14
ATM717-054Maintenance History Page
1
2
Main Menu Page
< CURRENT STATUS
< IDENT/CONFIG
< INPUT MONITORING
< INDEX
APU BITE TEST MAIN MENU
1/
MAINTENANCE MESSAGEUNKNOWN FLT DECK EFFECTMAINT MSG 49-71146EGT 1 THERMOCOUPLEDISAGREES WITH EGT 2DATE GMT STARTS OLDAPR 13 1101 1
< INDEX < INDEX
CURRENT STATUS> S
OTHER OCCURRENCES>
MAINTENANCE MESSAGE
EGT 1 THERMOCOUPLEDISAGREES WITH EGT 2OTHER OCCURRENCES/STARTS
APU BITE TEST 1/20 APU BITE TEST 1/20
Press to ViewMaintenanceHistory Pages
Press to viewOther Occurrences
< FAULT HISTORY
OIL QUANTITY >
MAINTENANCE HISTORY>
Maintenance History Page Other Occurrences Page
UNKNOWN FLT DECK EFFECTMAINT MSG 49-71146
1 2 11 31 99 200
Maintenance History Page
ATM717.05409/02
1/1
Electronic Control Unit Operation and Interrogation Control Display Unit (CDU) Page 3-15
131-9B Line Maintenance Training Manual
INPUT MONITORING PAGE
PurposeThe Input Monitoring pages display the APU parameters.
DescriptionThis menu displays APU operating parameters in real time toassist the operator in APU fault isolation.
To display the next page of information, push the NEXT PAGE but-ton on the CDU.
Maintenance Tip• The parameters displayed on the Input Monitoring page
can be used to assess the APU health.• The basic parameters, EGT, speed, and inlet temperature
are readily available for reference.• This information is only available when the aircraft is on
the ground.
Electronic Control Unit Operation and Interrogation Control Displa
Notes:
y Unit (CDU) Page 3-16
ATM717-055Input Monitoring Page
Main Menu Page
1
< I N D E X
A P U B I T E T E S T 2/4INPUT MONITORING
OIL TEMPFUEL TEMPGENERATOR LOADSTART SWITCHAPU ON SWITCHAPU OFF SWITCHMES SWITCH(S)AIR/GROUNDLEFT PACKRIGHT PACK
A P U B I T E T E S T 3/4INPUT MONITORING
A P U B I T E T E S T 4/4INPUT MONITORING
77 C50 C
YES
NOOFF
LOW
54.0 KW
YES
OFF
LOW
A P U B I T E T E S T 1/4INPUT MONITORING
< I N D E X
SPEEDEGTIGV POSITIONSCV POSITIONDELTA PRESSTOTAL PRESSINLET PRESSINLET TEMPFUEL TMCFUEL FLOW
100.0%440 C
89.5 DEG
38.3 PSIA14.4 PSIA
148 MA
45.8 DEG
4.9 PSID
10.2 C
231 PPH
BLEED COMMAND SWINLET DOOR OPENDOOR NOT FULL OPENFIRE COCKPITFIRE REMOTE HANDLEFIRE DETECTIONAIRPLANE MODELBLEED AIR VALVEFUEL VALVE CLOSEDFUEL VALVE OPEN
ONYES
NO
NO700
NO
NO
NO
OPEN
YES< I N D E X
READY TO LOADSTART COMMANDLOAD SHED COMMANDIGNITION COMMANDFUEL SOL COMMANDBLEED SOL COMMANDOVERSPD INDICATORFAULT INDICATORLOP INDICATORMAINT INDICATOR
YESNO
NO
YESNO
NO
NO
YES
NO
NO< I N D E X
MAINTENANCE HISTORY >
OIL QUANTITY >
< CURRENT STATUS
< FAULT HISTORY
< IDENT/CONFIG
< INPUT MONITORING
< INDEX
APU BITE TESTMAIN MENU
1/1
Input Monitoring Page 2/4 Input Monitoring Page 4/4Input Monitoring Page 3/4
Input Monitoring Page 1/4
Press to viewInput MonitoringPages
Input Monitoring Page
ATM717.05509/02
Electronic Control Unit Operation and Interrogation Control Display Unit (CDU) Page 3-17
131-9B Line Maintenance Training Manual
IDENT/CONFIG PAGE
Data Memory Module (DMM)The Ident/Config page displays all data in the data memory mod-ule.
To display the Ident/Config data, press the NEXT PAGE button onthe CDU.
This menu shows the following items:• APU serial number• Hours of operation• Number of starts• ECU part number and serial number• ECU software version.
Electronic Control Unit Operation and Interrogation Control Displa
Notes:
y Unit (CDU) Page 3-18
ATM717-056IDENT/CONFIG Page
IDENT/CONFIG BITE Interrogation
Page 1
Page 2
1
MAINTENANCE HISTORY >
< CURRENT STATUS
APU BITE TESTMAIN MENU
1/1
< FAULT HISTORY
< IDENT/CONFIG
< INPUT MONITORING
< INDEX OIL QUANTITY >
IDENT/CONIG 1/2APU BITE TEST
APU S/NAPU HOURS
APU CYCLESHOURS SINCEINSTALLATIONON AIRPLANE
P-0013552.44296
3552.4
ECU HW P/NECU S/N
2118966-03166B00001
< INDEX INSTALLATION >
IDENT/CONIG 2/2APU BITE TEST
ECU OPERATIONAL SW P/N4900-TUS-A00-01
< INDEX
DATA MEMORYMODULE >
Press to viewIDENT/CONFIG
screens
Note:Press thekeys on the CDU foradditional pages
PREV/NEXT
IDENT/CONFIG Page
ATM717.05609/02
Electronic Control Unit Operation and Interrogation Control Display Unit (CDU) Page 3-19
131-9B Line Maintenance Training Manual
OIL QUANTITY
PurposeThe Oil Quantity page displays the APU oil level. It shows eitherFULL, LOW or ADD.
DescriptionADD oil means approximately two quarts low.
LOW oil means there are two quarts left in the gearbox. TheMAINT light will illuminate when the low oil level is reached.
Electronic Control Unit Operation and Interrogation Control Displa
Notes:
y Unit (CDU) Page 3-20
ATM717-103Oil Quantity
APU BITE TESTOIL QUANTITY REPORT
OIL LEVEL AD DACTIVE FOR 2.5 HOURS
Oil Quantity
ATM717.10309/02
Low Oil QuantitySwitch
CDU
(INPUT/MONITORING MENU)
Electronic Control Unit Operation and Interrogation Control Display Unit (CDU) Page 3-21
131-9B Line Maintenance Training Manual
SUMMARY
Now that you have completed this section, you should be able to:
• Identify the inputs and outputs to the ECU.• Explain the main functions of the electronic control unit
(ECU): start sequencing, speed governing, load sequencing, shutdown sequencing.
• Describe the purpose of each APU menu page.
What are the inputs and outputs to the ECU?Refer to the diagram on page 3-5.
What are the main functions of the electronic control unit?
Start SequenceThe APU starts automatically after placing the APU Master switchto “START”. The ECU controls the ignition and fuel automaticallyas required for ambient conditions.
During pre-start Built-In-Test-Equipment (BITE), if a failure isdetected that would critically affect APU operation, the ECU inhib-its starting of the APU until the failure is resolved. The failure isstored in the ECU and the APU FAULT indicator is illuminated onthe APU control panel.
Speed GoverningExhaust gas temperature and engine speed are continuouslymonitored by the ECU. Once on-speed, the ECU maintains enginespeed at 48,800 RPM (±1.0%).
Load SequencingThe ECU regulates the APU pneumatic output by sensing the APUEGT and comparing this to a predetermined schedule within the
Electronic Control Unit Operation and Interrogation Summ
ECU. Bleed extraction is reduced to prevent an overtemperaturecondition.
ShutdownThe ECU shuts down the APU if engine speed exceeds 106% orEGT exceeds 1175F (635C).
The ECU has the authority to shut down the APU when BITE indi-cates that continued APU operation might cause damage. Uponrequest, the ECU reports all APU fault data to the CDU. Thisallows troubleshooting of APU fault data.
Notes:
ary Page 3-22
What is the purpose of each of the six APU menu pages?• Current status: shows currently active maintenance faults• Fault history: shows faults that cause the APU to shutdown
or abort a start.• Maintenance history: shows faults that turn on the MAINT
light on the P5 panel and faults that have no flight compartment indication.
• Ident/Config (DMM data included): shows APU serial number, hours of operation, number of starts, ECU part and serial number, ECU software version.
• Input monitoring: shows APU operating parameters to assist in fault isolation.
• Oil quantity: shows the APU oil level as either FULL, LOW or ADD.
Electronic Control Unit Operation and Interrogation Summ
Notes:
ary Page 3-23
131-9B Line Maintenance Training Manual
Electronic Control Unit Operation and Interrogation Summ
Notes:
ary Page 3-24
131-9B Line Maintenance Training Manual
CHAPTER 4—THEORY OF OPERATION &
CONSTRUCTION
OBJECTIVES
Upon completion of this chapter, you will be able to:• Identify the major APU Sections.• Explain the basic operating cycle of the turbine engine.• Explain the effect of load compression on engine
operation.• Explain the effect of a surge on engine operation.• Explain the effect of a generator load on engine operation.• Explain how APU Temperature controls effects engine
operation.
Theory of Operation & Construction Objec
Notes:
tives Page 4-1
131-9B Line Maintenance Training Manual
OVERVIEW
ConstructionThe APU is divided into three major sections:
• Power section• Load compressor section • Accessory gearbox section
Theory Of OperationThe APU is designed to provide:
• pneumatic power for main engine start (MES), and the environmental control system (ECS),
• shaft power to drive a customer furnished generator for the aircraft electrical system.
Both shaft and bleed loads are placed upon the APU during opera-tion. Temperature control is accomplished through sensor inputto the ECB.
Theory of Operation & Construction Overv
Notes:
iew Page 4-2
ATM717-002Main APU Engine Sections
Main APU Engine Sections
Gearbox Load Compressor Power SectionATM717.002
09/02
Theory of Operation & Construction Overview Page 4-3
131-9B Line Maintenance Training Manual
MAIN APU ENGINE SECTIONS
The basic APU is comprised of three major sections:• Power section• Load compressor section • Accessory gearbox section
Power SectionThe power section drives the load compressor and accessorygearbox. It consists of a shaft with a single centrifugal impellerand a two-stage axial turbine all protected by a containmentstructure. There are also 10 fuel nozzles and a reverse flow annu-lar combustor.
Load CompressorThe load compressor consists of a single centrifugal impeller anda diffuser. Inlet air to the load compressor is controlled by inletguide vanes. The power section and load compressor impellersshare the same inlet plenum duct.
Accessory GearboxThe accessory gearbox is driven through a quill shaft by the highspeed torque of the power section. The gearbox contains a seriesof spur gears to drive the APU accessories. Accessories installedon the gearbox are the oil cooled generator, oil pump/fuel control,cooling fan and starter motor. The gearbox also serves as a reser-voir for the lubrication system.
Theory of Operation & Construction Main APU En
Notes:
gine Sections Page 4-4
ATM717-002Main APU Engine Sections
Main APU Engine Sections
Gearbox Load Compressor Power SectionATM717.002
09/02
Theory of Operation & Construction Main APU Engine Sections Page 4-5
131-9B Line Maintenance Training Manual
BASIC OPERATING CYCLE
At the heart of the APU is a turbine engine that is similar in oper-ation to a jet engine, but it produces no thrust. The compressorand turbine are mounted on a common shaft. Initially turned by astarter, using electrical power, the compressor draws air throughthe air inlet raising its pressure, then passes it into the combustorwhere fuel is injected. The burning within the combustor raisesthe energy level of the air. The hot gases then pass through theturbine, which extracts as much energy as possible from the gasflow. The turbine converts the gas energy to rotational energy todrive the compressor. Even with no load applied, it is necessary toinject heat energy into the combustor by burning fuel to over-come the losses that occur within the compressor turbine, andother mechanical/aerodynamic drag.
The amount of fuel which the unit burns and the heat which isexpelled from the exhaust are indicators of engine health. Ascomponents wear or malfunctions occur, a rise in exhaust gastemperature and an increase in fuel consumption can occur.
Theory of Operation & Construction Basic Opera
Notes:
ting Cycle Page 4-6
ATM717-102Basic Operating Cycle
Basic Operating Cycle
ATM-717.102 (07/02)
Fuel
InletAir
Compressor
Combustor
Turbine
Theory of Operation & Construction Basic Operating Cycle Page 4-7
131-9B Line Maintenance Training Manual
LOAD COMPRESSOR OPERATION
The APU supplies compressed air for air conditioning, and mainengine starting. This air is obtained by a second compressorcalled the load, or driven compressor. It is driven from an exten-sion of the power section compressor turbine shaft.
The load compressor takes air from the same inlet as the powersection compressor. It compresses it and supplies it to the aircraftthrough a load control valve. The load control valve shuts off theair flow from the load compressor when there is no demandplaced on the APU by the aircraft control system. The energyrequired to drive the load compressor is obtained from the turbineby burning more fuel in the combustor. As air is extracted fromthe load compressor, fuel flow and exhaust gas temperature rise.
The load compressor must provide the maximum amount of airflow that the aircraft will require. If there were no control overairflow, it would impose full load on the turbine and require a veryhigh fuel flow, whether or not the aircraft demanded air. Inletguide vanes between the compressor and the air inlet matchcompressor flow to the demand. Inlet guide vane position is con-trolled by the electronic control box in response to aircraftdemand. When there is no demand, the ECB closes the IGV's tothe lowest possible setting, so the load compressor imposes min-imum load on the power section. In this condition, the load con-trol valve is closed and all air is redirected through the surgecontrol valve. When the IGV's are at the minimum closed posi-tion, the unit is “ready-to-load”, which means the APU is run-ning on-speed, with bleed de-activated and the generator off.
Theory of Operation & Construction Load Compres
Notes:
sor Operation Page 4-8
ATM717-097Load Compressor OperationI
GVA
ECU
Load Compressor Operation
ATM-717-097 (09/02)
Bleed AirValve
LoadCompressor
Compressor Turbine
Air Intake
Combustor
Aircraft
DemandsFuel
Theory of Operation & Construction Load Compressor Operation Page 4-9
131-9B Line Maintenance Training Manual
SURGE PROTECTION
Although the air conditioning system may be turned on in the air-plane, it may not be using as much air as the load compressorcan deliver. If the airflow from the compressor falls too far belowthe rate at which it enters through the IGV's, a back pressurecondition known as compressor stall can occur. A significant backpressure of the compressor results in a surge.
A surge control valve spills air that the compressor wants todeliver but the airplane cannot use, to protect the load compres-sor from a stall/surge condition. For any opening in the inlet guidevanes, there is a minimum amount of air that must be allowed toflow through the compressor. Actual flow is sensed by the flowsensor which through the ECB controls the position of a surgecontrol valve.
Theory of Operation & Construction Surge Pro
Notes:
tection Page 4-10
ATM717-098Surge Protection
EHSV
ECU
LVDT
ATM-717-098 (09/02)
Exhaust
SCV Control and Feedback
Signals
Diffuser
FuelSupply
IGV PositionAir Inlet Temperature
Pneumatic System Demands
FlowSensors
PT
DP
Load Compressor
AircraftDuct
SurgeControlValve
Surge Protection
Theory of Operation & Construction Surge Protection Page 4-11
131-9B Line Maintenance Training Manual
GENERATOR AND ACCESSORIES
The APU drives the electrical generator mounted on the gearboxassembly. The gearbox in turn is driven from the power sectionthrough the common shaft as shown in the figure. Whether theAPU is bleeding air from the load compressor or taking electricalpower from the generator, each will impose a load on the powersection. As load is applied, the power section tends to slow down.The electronic control box senses the speed drop and providesmore fuel to the combustor. This results in an increase in thepower to match the load which helps maintain a constant speed.
Theory of Operation & Construction Generator and
Notes:
Accessories Page 4-12
ATM717-099Generator and Accessories
GCU
IGVA
ECU
PT
DP
Gearbox
Generator And Accessories
ATM-717-099 (09/02)
Gen
Speed
Starter
Lube andFuel
Clusters
SurgeControlValve
Bleed Air Valve
Fuel
Theory of Operation & Construction Generator and Accessories Page 4-13
131-9B Line Maintenance Training Manual
APU TEMPERATURE CONTROL
As the combined loads of the generator and the load compressorare imposed on the power section, the speed governing functionof the ECB responds by increasing fuel flow. Under someextremely high combination loads or with significant deteriorationof the power section, the turbine trim temperatures limit will bereached. The trim limit is set below the maximum temperaturelimit of the turbines temperature to ensure long life.
The ECB monitors turbine temperature through a pair of dualthermocouples located in the turbine exhaust. When a loadchange results in a temperature higher than its setpoint, the ECBmoves the IGV’s toward a more closed position, reducing loadcompressor airflow, and thus reducing the load and its resultingturbine temperature.
Theory of Operation & Construction APU Tempera
Notes:
ture Control Page 4-14
ATM717-100APU Temperature ControlI
GVA
ECU
PT
DP
Gearbox
APU Temperature Control
ATM-717-100 (09/02)
Speed
Gen
Starter
Lube andFuel
Clusters
EGT
SurgeControlValve
Bleed AirValve
Exhaust
Fuel
Theory of Operation & Construction APU Temperature Control Page 4-15
131-9B Line Maintenance Training Manual
SUMMARY
Now that you have completed this section, you should be able to:
• Identify the major APU Sections.• Explain the basic operating cycle of the turbine engine.• Explain the effect of load compression on the engine
operation.• Explain the effect of a surge on the engine operation.• Explain the effect of a generator load on engine operation.• Explain how APU Temperature controls effects engine
operation.
What are the major APU sections?• Power section• Load compressor section • Accessory gearbox section
What is the basic operating cycle of the turbine engine?The compressor draws air through the air inlet raising its pres-sure, then passes it into the combustor where fuel is injected. Theburning within the combustor raises the energy level of the air.The hot gases then pass through the turbine, which extracts asmuch energy as possible from the gas flow. The turbine convertsthe gas energy to rotational energy to drive the compressor.
What is the effect of load compression on engine operation?
The load compressor must provide the maximum amount of airflow that the aircraft will require. If there were no control overairflow, it would impose full load on the turbine and require a veryhigh fuel flow, whether or not the aircraft demanded air. Inletguide vanes between the compressor and the air inlet matchcompressor flow to the demand. Inlet guide vane position is con-
Theory of Operation & Construction Summ
trolled by the electronic control box in response to aircraftdemand. As the IGVVs open, the load comp0ressor imposes aload on the power section which causes the APU to slow down.The ECB senses the speed drop and provides more fuel to bringthe APU up to 100% speed.
What is the effect of generator load on engine operation?
The APU drives the electrical generator mounted on the gearboxassembly. The gearbox in turn is driven from the power sectionthrough the common shaft as shown in the figure. Whether theAPU is bleeding air from the load compressor or taking electricalpower from the generator, each will impose a load on the powersection. As load is applied, the power section tends to slow down.The electronic control box senses the speed drop and providesmore fuel to the combustor. This results in an increase in thepower to match the load which helps maintain a constant speed.
Notes:
ary Page 4-16
How does APU Temperature control effects engine operation?
The ECB monitors turbine temperature through a pair of dualthermocouples located in the turbine exhaust. When a loadchange results in a temperature higher than its setpoint, the ECBmoves the IGV’s toward a more closed position, reducing loadcompressor airflow, and thus reducing the load and its resultingturbine temperature.
Theory of Operation & Construction Summ
Notes:
ary Page 4-17
131-9B Line Maintenance Training Manual
Theory of Operation & Construction Summ
Notes:
ary Page 4-18
131-9B Line Maintenance Training Manual
CHAPTER 5—LUBRICATION SYSTEM
OBJECTIVES
Upon completion of this training section, you will be able to:• Locate and identify lubrication system LRUs.• Identify the purpose and operation of the lubrication
system components.• Trace the flow of oil through the lubrication system.• Identify possible malfunctions related to the lubrication
system.
Lubrication System Objec
Notes:
tives Page 5-1
131-9B Line Maintenance Training Manual
OVERVIEW
The lubrication system provides oil to lubricate, clean, and coolthe gears, bearings and shafts of the power section, load com-pressor and gearbox. The system consists of the supply, scav-enge, pressure, temperature and vent systems.
There are two main areas in the APU that require lubrication. Atthe front is the accessory gearbox that houses gears, shafts andthe duplex ball bearing that supports the front end of the rotatinggroup. The other area is the roller bearing on the turbine powersection.
Lubrication System Overv
Notes:
iew Page 5-2
ATM717-101Lubrication System Overview
Lubrication System Overview
ExhaustGenerator
LubeModule
BypassValve
Gearbox
ScavengeReturns toGearbox
Air/OilSeparator
GearboxVent Line
OilCooler
ScavengePumpReturnScreen
InletScreen
Oil Level
PowerSection
OilJetsForGear-boxBear-ings
ATM-717-101 (09/02)
Lubrication System Overview Page 5-3
131-9B Line Maintenance Training Manual
POWER SECTION TURBINE BEARING CAVITY
The flow of oil through the power section turbine bearing cavity isas follows:
• The lubricating oil enters the rear turbine cavity through a tube to lubricate the rear turbine roller-bearing.
• When the oil has reached the bearing cavity, it circulates and migrates down into the lower part of the cavity.
• In the lower cavity, it is picked up by the scavenge tube and drawn back by a scavenge pump into the gearbox.
Fault Indication:Scavenge pump failure will leave oil in the turbine cavity longerthan intended. This will result in black oil and possible oil temper-ature auto-shutdowns.
Smoke out of the APU exhaust could indicate that the aft gaskethas failed on the turbine cover.
Lubrication System Power Section Turb
Notes:
ine Bearing Cavity Page 5-4
ATM717-035Power Section Turbine Seal Cavity
Power Section Turbine Seal Cavity
ATM717.03509/02
ScavengeOut Port
TurbineRoller
Bearing
Metal Rotor Seal
Carbon SealOil InPort
Lubrication System Power Section Turbine Bearing Cavity Page 5-5
131-9B Line Maintenance Training Manual
FORWARD BEARING AND SEAL
Air discharged from the load compressor is fed into the cabin andvarious pneumatic components. This requires that extra protec-tion for oil leakage be incorporated for the forward bearing.
• At the forward end of the rotating group, the duplex ball bearing is separated from the load compressor by a carbon face seal.
• The carbon face seal is backed up with an air buffered labyrinth seal.
• This extra protection for oil leakage is required because Compressor discharge air is fed into the area between the carbon face seal and the labyrinth seal through covered passages.
• If any oil should get past the carbon face seal, it would be forced back toward the gearbox rather than entering the load compressor.
Maintenance TipA seal leakage witness port is located on the lower part of theload compressor to check if the seal is in fact leaking.
If the APU is suspected of being the source of odors, mainte-nance personnel should troubleshoot for a reason.
Lubrication System Forward Bear
Notes:
ing and Seal Page 5-6
ATM717-036Forward Bearing and Seal
Forward Bearing and Seal
ATM717.03609/02
Compressor Scroll
LoadCompressor
ImpellerSeal
WitnessTest Port
DuplexBall
Bearing
Lubrication System Forward Bearing and Seal Page 5-7
131-9B Line Maintenance Training Manual
LUBRICATION SYSTEM COMPONENTS
The lubrication system components include the following:• Lubrication Module
- Lube Supply Filter- Generator Scavenge Filter- High Oil Temperature Sensor
• Oil Cooler• Gearbox/Oil Sump• Low Oil Quantity Switch• Magnetic Chip Collector/Drain Plug• Temperature Control Valve• Low Oil Pressure Switch• Air/Oil Separator
Lubrication System Lubrication Syste
Notes:
m Components Page 5-8
ATM717-082Lubrication System Components
Lubrication System Components
ATM-717.082 (09/02)
• Lubrication Module
• Lube Supply Filter
• Generator Scavenge Filter
• High Oil Temperature Sensor
• Oil Cooler
• Gearbox / Oil Sump
• Low Oil Quantity Switch
• Magnetic Chip Collector/Drain Plug
• Temperature Control Valve
• Low Oil Pressure Switch
• Air/Oil Separator
Lubrication System Lubrication System Components Page 5-9
131-9B Line Maintenance Training Manual
LUBRICATION MODULE
Identification and LocationThe lubrication module mounts directly to the gearcase.
Purpose and InterfaceThe lubrication module is a self-contained unit, that provideslubrication and scavenge functions to the starter/generator, gear-box, and main shaft bearings.
Functional DescriptionThe lubrication module incorporates a three-element ge-rotorpressure pump, a three-element ge-rotor scavenge pump forclearing oil from the generator, and a single element ge-rotorscavenge pump, 7 in all, for clearing oil from the APU turbinebearing cavity.
To enhance cold starting, ceramic ge-rotor rings are used inthe 131-9[B] configuration. The ceramic rings have a lower ther-mal coefficient of expansion than that of the steel ge-rotor ele-ments. This allows a larger cold clearance between the ge-rotorand ring to minimize cold temperature viscous drag withoutsacrificing performance when operating with hot oil.
The filters, and indicators are accessible with the lube moduleinstalled on the APU and are removed and installed with standardtools.
The module incorporates a seal plate to provide sealing featuresat each oil passageway. This eliminates the need for externaltubes at the lube module.
Pressure Regulator A pressure regulator (67.5±7 psi) maintains a constant lubesupply pressure to the engine and starter/generator which isinstalled on the lube module.
Lubrication System Lubrication Syste
Ultimate Relief Valve AssemblyThe ultimate relief valve assembly (240±40 psi) is locatedinside the lube module. It’s responsibility is to prevent over pres-surization of the oil system.
The Lubrication Module is an LRU.
Notes:
m Components Page 5-10
ATM717-030Lubrication Module
Lubrication Module
ATM717.03009/02
Captive Bolts
Oil PressureTest Port
LUBE
SCAV
Lubrication System Lubrication System Components Page 5-11
131-9B Line Maintenance Training Manual
LUBE SUPPLY FILTER
The oil filter elements are throw-away types contained in ahouseing that is screwed into the Lube Module housing. The 2 fil-ters are rated at 10 micron nominal and 25 microns absolute.The collapse pressure of the filter exceeds 350 psid.
Purpose and InterfaceThe oil filter elements remove contaminants from the oil as itreturns to the oil storage area.
Functional DescriptionThe Lube filter housing is equipped with a DP indicator but-ton. Should the lube filter become contaminated, the differentialpressure (DP) indicator pops out at 35±5 psid.
If additional contamination buildup occurs, the filter bypass valveallows unfiltered oil to bypass the filter at a differential pressureof 60±10 psid.
A thermal lockout feature is incorporated in the assembly so theDP feature is inoperative when oil temperature is less than 70°F.
GENERATOR SCAVENGE FILTER
The generator scavenge filter and filter bypass valve areidentical to but entirely separate from the lubrication oil filter.This part of the lube system contains an electrical impendingbypass switch.
The purpose of the generator switch is to eliminate and mini-mize damage to the APU if the starter/generator should malfunc-tion by shutting down the APU before generator debris cancirculate in the lubrication system.
Lubrication System Lubrication Syste
When the bypass switch activates, a signal is sent to the ECU.There are three conditions that must be met before theECU will shutdown the APU:
1. Oil temperature >100°F2. For >5 seconds3. Aircraft must be on ground
NOTE: If a signal is generated in flight, the ECU will log a maintenance fault to the APU maintenance page of the CDU.
Notes:
m Components Page 5-12
ATM717-031Oil Filter Elements
Oil Filter Elements
ATM717.03109/02
Lube Module
LubeReservoir
Filter Element
Starter/GeneratorScavenge
Filter Element
BypassSwitch
RetainingRing Groove
LUBE
SCAV
Lubrication System Lubrication System Components Page 5-13
131-9B Line Maintenance Training Manual
HIGH OIL TEMPERATURE SENSOR
Identification and LocationThe high oil temperature sensor is located in the lubricationmodule.
The high oil temperature sensor is used for high oil temperatureindication/protection.
Functional Description• Normal operating oil temperature is approximately 200-
210°F on a standard sea level day.• A high oil temperature shutdown will occur when APU
speed is >95%, oil temperature is >290°F, plus 10 seconds.
• The sensor is checked during Pre-start, Monitor and Self-test.
The high oil temperature sensor is an LRU.
Fault Indication: Oil Temp shutdowns• Sensor failure results in the APU would not have HOT
protection• Low oil quantity• Dirty oil cooler assembly• Thermostatic bypass valve failure• Lube pump failure (pressure and scavenge)
Lubrication System Lubrication Syste
Notes:
m Components Page 5-14
ATM717-034High Oil Temperature Sensor
High Oil Temperature Sensor
ATM717.03409/02
High OilTemperature
Sensor
Lube Module
Lubrication System Lubrication System Components Page 5-15
131-9B Line Maintenance Training Manual
OIL COOLER
Identification and LocationThe oil cooler is a aluminum air/oil heat exchanger of the two-pass-folded crossflow type with the oil flowing perpendicular tothe direction of airflow twice.
Purpose and InterfaceThe oil cooler removes the waste heat in the lubrication oil andcarries it away from the APU and the starter/generator.
Functional DescriptionCooling air for the oil cooler is supplied by the cooling educatorduct from the tail of the airplane. The high speed exhaust flowfrom the APU forms a low pressure area. This low pressure areapulls cooler air from outside through the eductor duct to the APUcompartment. This low pressure area also pulls air continuouslyfrom the compartment through the oil cooler and out through theexhaust.
Maintenance TipThe cooler air side is easily cleaned of ingested contaminants withcommonly available shop equipment.
NOTE: This new design has eliminated the need for a oil cooling fan on the 131-9B APU.
Lubrication System Lubrication Syste
Notes:
m Components Page 5-16
ATM717-076Oil Cooler
Oil Cooler
ATM717.076 (09/02)
Oil Cooler
Cooler ReturnTube
CoolerSupplyTube
CaptiveBolt
Heat Shield
APU CompartmentAirflow Exit
Lubrication System Lubrication System Components Page 5-17
131-9B Line Maintenance Training Manual
GEARBOX / OIL SUMP
Identification and LocationThe gearbox/oil sump is mounted to the front of the load com-pressor housing.
All accessories are mounted on the front of the gearbox assemblyto maximize maintainability.
Purpose and InterfaceThe gearbox/oil sump drives the APU accessories, including theStarter/Generator. It is also the reservoir for the lubrication sys-tem.
Functional DescriptionThe gearbox is designed as a module and is removable from theAPU, leaving all gears, bearings, and seals in place.
The gearbox is considered a HOT gearbox, because the oil in itcomes from the working APU before oil cooling occurs.
Oil capacity is 8.8 quarts (8.4 liters), and the ADD point is 4.0quarts. The G/B holds approx. 5.7 quarts, while the lines andcooler hold approx. 3.8 quarts.
Maintenance TipPeriodically check the end of the vent tube (turbine exhaust) forcarbon buildup.
Lubrication System Lubrication Syste
NOTE: Maximum oil consumption allowed is approximately 8 cc’s per hour.
Fault Indication:A plugged vent line will cause oil pressure to increase, oil con-sumption, gearbox cracking, and oil being pushed through theseals.
Smoke out the APU exhaust and smells in bleed air will benoticed.
The gearbox assembly is a Shop Replaceable Unit (SRU).
Notes:
m Components Page 5-18
ATM717-027Gearbox/Oil Sump
Gearbox/Oil Sump
ATM717.02709/02
Air/OilSeparator
MagneticDrain Plug
Bypass PressureDifferential
Switch
Lube Filter
GeneratorScavenge
Filter
Oil FillPort
Lubrication System Lubrication System Components Page 5-19
131-9B Line Maintenance Training Manual
LOW OIL QUANTITY SWITCH
Identification and Location The low oil quantity switch is located on the gearbox next to theoil fill port.
Purpose and InterfaceThe low oil quantity switch indicates when a low oil conditionoccurs and sends a signal to the CDU.
Functional Description• The low oil quantity switch uses four reed -switches (one
full, two add, and one low) to ensure reliable nuisance-free indication. The quantity indicated is not dynamic, it is checked upon start-up.
• The low quantity switches are actuated by a float/samarium cobalt magnet combination that moves depending on oil level. The float has strategically placed slots to prevent trapping of air by the float.
• The CDU displays the APU oil quantity with a FULL, ADD, or LOW indication, under the “input monitoring” screen.
NOTE: Approximately 70 hours (maximum allowed oil consumption) of APU operation remain once the ADD indication is seen on the CDU.
Lubrication System Lubrication Syste
Notes:
m Components Page 5-20
ATM717-028Low Oil Quantity Switch
APU BITE TESTOIL QUANTITY REPORT
OIL LEVEL AD DACTIVE FOR 2.5 HOURS
Low Oil Quantity Switch
ATM717.02809/02
Low Oil QuantitySwitch
CDU
(INPUT/MONITORING MENU)
Lubrication System Lubrication System Components Page 5-21
131-9B Line Maintenance Training Manual
MAGNETIC CHIP COLLECTOR AND DRAIN PLUG
Identification and LocationThe magnetic chip collector is a threaded metal plug, withwrenching flats on one end, and a magnet on the opposite end.
Purpose and InterfaceThe magnetic chip collector detects metallic particles in the oil.The check valve on the drain plug prevents oil loss when inspect-ing the chip collector.
The magnetic chip collector and drain plug assembly are an LRU.
Maintenance TipRefer to applicable maintenance manual for the meaning andmaintenance action for particles that may appear.
If any of the filters or chip detector is contaminated, change thecontaminated oil, filter element(s) and recheck after 15 minutesof APU operation. If further contamination is seen, refer to appro-priate maintenance manual for disposition.
NOTE: If you see metal particles on the magnetic element, examine the engine to find the cause and quantity of the damage.
Lubrication System Lubrication Syste
Notes:
m Components Page 5-22
ATM717-029Magnetic Chip Collector/Drain Plug
Magnetic Chip Collector/Drain Plug
ATM717.029R109/02
Magnetic Chip Collector
Magnet
Plug
RetainingClamp
Check Valve
Gearbox
Oil Filler Housingwith Strainer
Oil Fill Cap
Lubrication System Lubrication System Components Page 5-23
131-9B Line Maintenance Training Manual
TEMPERATURE CONTROL VALVE
Identification and LocationThe temperature control valve is remotely located on the gearboxand is attached by a seal plate.
Purpose and InterfaceThe temperature control valve allows the flow of oil to either flowthrough or bypass the cooler, depending on oil temperature.
Functional DescriptionThe control valve allows oil to bypass the oil cooler at tempera-tures less than 140°F. Oil flows through the cooler when temper-atures are greater than 170°F.
The valve opens to allow oil to bypass the oil cooler when:• it is internally restrictive to oil flow.• the oil temperature is less then 140° F.• there is a differential pressure of (50 psid) across the oil
cooler assembly.
If the temperature control valve fails to close, H.O.T. shutdownswould most likely occur.
NOTE: This feature helps the cold APU start by not putting an extra strain on the APU starter system.
Lubrication System Lubrication Syste
Notes:
m Components Page 5-24
ATM717-032Temperature Control Valve
Temperature Control Valve
ATM717.03209/02
Poppet Valve
OilIn
OilOut
ToOil
Cooler
FromOil
Cooler
Oil CoolerSupply Tube
Oil CoolerReturn Tube
ThermostaticBypassValve
Diaghragm
ExpansionElement
TemperatureSensitive
Compound
Lubrication System Lubrication System Components Page 5-25
131-9B Line Maintenance Training Manual
LOW OIL PRESSURE (LOP) SWITCH
Identification and LocationThe oil pressure switch is located in the gearcase, in the oil flowto the engine bearings.
The LOP switch is a normally closed electrical, open-with-pres-sure switch.
Purpose and InterfaceThe low oil pressure switch provides protection against low oilpressure conditions.
Functional DescriptionA open pressure switch position is checked in Pre-Start andSelf-test ECU modes only and not during APU operation.
On pre-start BIT, the LOP switch has failed if the APU speed is lessthan 7% and the switch is showing electrically open.
An Oil Pressure auto-shutdown will occur if RPM >95%, oil pres-sure <35±5 psi for 20 seconds.
The APU would start but have no LOP protection if found tobe bad during Pre-Start BIT
The Oil Pressure switch is an LRU.
Lubrication System Lubrication Syste
FAULT INDICATION: LOP AUTO-SHUTDOWNPossible causes:
• Oil filters clogged.• Insufficient oil quantity.• Over servicing of the oil.• Mixing of incompatible oils.• Sludge buildup in APU internal cored passageways.
Notes:
m Components Page 5-26
ATM717-033Low Oil Pressure Switch
Low Oil Pressure Switch
ATM717.03309/02
Low OilPressure Switch
Lubrication System Lubrication System Components Page 5-27
131-9B Line Maintenance Training Manual
AIR-OIL SEPARATOR
Identification and LocationThe oil-air separator is located right above and to the left of thelubrication module.
Purpose and InterfaceIn scavenging the oil from the bearing cavities, some air will bedrawn with it since the scavenge pump capacity is greater thanthe oil flow to the turbine cavity. The scavenged air/oil mixture issaturated with oil mist, and must separated. The gearcase mustbe vented to prevent the buildup of pressure.
The air-oil separator removes the air from the oil mist as itreturns to the gearbox reservoir.
Functional DescriptionAir and oil come into the gearbox from the air buffered seals. Oilis then slung to the sides and re-deposited into the sump. The airthen vents overboard through a hard-line tubing going back tothe APU exhaust duct.
Maintenance Tip• The stationary air-oil carbon seal is removable and
replaceable without gearbox disassembly. The rotor, however is not.
• The rotating group can be turned by using a 5/16 socket to turn the air/oil separator, after the cover has been removed.
The Air-Oil Separator assembly is not an LRU.
Lubrication System Lubrication Syste
Notes:
m Components Page 5-28
ATM717-037Air/Oil Separator (Top View)
Air/Oil Separator (Top View)
ATM717.03709/02
Air/OilSeparator
GearboxVent toExhaust
Vent toExhaust
Pipe
Metal Rotor
Carbon Face Seal
Gearbox
Air/Oil SeparatorCompoundIdler Gear
Air/OilIn
Lubrication System Lubrication System Components Page 5-29
131-9B Line Maintenance Training Manual
OIL SERVICING PROVISIONS
The following synthetic lubricants are approved by Honeywell.
Type 1 per MIL-LP7808:Aeroshell Turbine Oil 390
Brayco 880
BP Aero Turbine Oil 15
Castrol 3C
Castrol 325
Type II per MIL-L-23699:Castrol 500
Exxon or Esso Turbine Oil 2380
Exxon or Esso Turbine Oil 85
Exxon 2197
Hatcol 3611
Mobil Jet Oil II
Mobil Jet Oil 254
Royco 899
Royco or Aeroshell Turbine Oil 500
Royco or Aeroshell Turbine Oil 555
Lubrication System Oil Servicing
NOTE: The use of non-approved lubricants or the mixing of brands and types of lubricants may cause foaming, and “Low Oil Pressure” auto shutdowns.
NOTE: Information concerning oil change intervals and a table listing the approved oil brands and type are provided in the appropriate maintenance manual.
Notes:
Provisions Page 5-30
Notes
Lubrication System Oil Servicing Provisions Page 5-31
131-9B Line Maintenance Training Manual
LUBRICATION SYSTEM FLOW
The following text describes the flow of oil through the engine.• Oil is drawn from the reservoir through a protective screen
into the 3-element supply pump. After being discharged from the pump the oil passes through a pressure regulator/relief valve which maintains constant system pressure throughout APU operation.
• The oil then flows to the thermostatic/pressure relief valve on the oil cooler.- If oil is cold, it bypasses the cooler and is distributed to
the engine and components.- If the oil is hot, it passes through the cooler to remove
excess heat.• Oil then flow to the lube filter and is distributed to the
bearings, gears, and generator. Oil is distributed through internal passages and external lines to the various parts of the APU.- As it flows to the turbine bearing, a pressure switch
and temperature sensor monitor system pressure and temperature. If pressure is too low or temperature is too high, the APU is shut down.
• The generator is scavenged by elements in the lube module. Oil returning from the generator first passes through in-line screens. The pumps discharge oil into a generator scavenge filter and empties it into the reservoir. The generator scavenge filter has an impending bypass switch that causes the APU to shutdown if the filter becomes restricted.
• Oil from the forward bearings and gearbox returns to the reservoir by gravity. The turbine bearing area is scavenged by a single pump element. Oil passes through an inlet screen, through the pump and into the reservoir.
Lubrication System Lubrication S
• Servicing provisions are on the reservoir case, as well as a sight gage.- There is an oil level sensor that signals the ECU. - In the bottom of the gearbox is a magnetic drain plug
that collects any metal particles for viewing in case of a suspected problem.
• Air and oil are separated by an air/oil separator. • The reservoir is vented to the exhaust section which
prevents over-pressurization of the reservoir during APU operation.
Notes:
ystem Flow Page 5-32
ATM717-026Lubrication System Flow
Lube Pump RegulatedLube Pump InletGearcase Vent AirTurbine ScavengeScavenge Pump DischargeGen. Scavenge Pump InletHigh Pressure Discharge
Lubrication System Flow
LubePump
Elements (3)
MagneticDrain Plug
Oil LevelSight Glass
LubeInlet
ScreenFillPort
Low Oil Quantity Switch
Gen. ScavengeElements (3)
TurbineScavengeElement
PressureRegulating/Relief Valve
Low OilPressureSwitch
Bearings
FCU
Oil Cooler
TemperatureControl Valve
OilTemp
Sensor
LubeFilter
Delta P Indicator Delta P
ImpendingBypassSwitch
GeneratorScavenge
Filter
To TailpipeVent
To Turbine Cavity
From Turbine Cavity
ATM717.02609/02
Lubrication System Lubrication System Flow Page 5-33
131-9B Line Maintenance Training Manual
SUMMARY
Now that you have completed this section, you should be able to:
• Locate and identify lubrication system LRUs• Identify the purpose and operation of the lubrication
system components.• Trace the flow of oil through the lubrication system.• Explain oil servicing provisions.
What are the lubrication system LRUs?• Lubrication Module
- Lube Supply Filter- Generator Scavenge Filter- High Oil Temperature Sensor
• Oil Cooler• Gearbox/Oil Sump• Low Oil Quantity Switch• Magnetic Chip Collector/Drain Plug• Temperature Control Valve• Low Oil Pressure Switch• Air/Oil Separator
What is the purpose of each LRU?• Lubrication Module: provides lubrication and scavenge
functions to the starter/generator, gearbox, and main shaft bearings.
• Oil Filter Elements: oil filter elements remove contaminants from the oil as it returns to the oil storage area.
• Low Oil Pressure Switch: provides protection against low oil pressure conditions.
Lubrication System Summ
• Lube Supply Filter: removes contaminants from the oil as it returns to the oil storage area.
• Oil Cooler: removes the waste heat in the lubrication oil and carries it away from the APU and the starter/generator.
• Gearbox/Oil Sump: drives the APU accessories and is also the reservoir for the lubrication system.
• Low Oil Quantity Switch: indicates when a low oil condition occurs and sends a signal to the CDU.
• Magnetic Chip Collector/Drain Plug: detects metallic particles in the oil.
• Temperature Control Valve: allows the flow of oil to either flow through or bypass the cooler, depending on oil temperature.
• High Oil Temperature Sensor: is used for high oil temperature indication/protection.
Notes:
ary Page 5-34
• Air/Oil Separator: removes the air from the oil mist as it returns to the gearbox reservoir.
What is the flow of oil through the lubrication system?• Oil is drawn from the reservoir through a protective screen
into the 3-element supply pump. After being discharged from the pump the oil passes through a pressure regulator/relief valve which maintains constant system pressure throughout APU operation.
• The oil then flows to the thermostatic/pressure relief valve on the oil cooler.- If oil is cold, it bypasses the cooler and is distributed to
the engine and components.- If the oil is hot, it passes through the cooler to remove
excess heat.• Oil then flow to the lube filter and is distributed to the
bearings, gears, and generator. Oil is distributed through internal passages and external lines to the various parts of the APU.- As it flows to the turbine bearing, a pressure switch
and temperature sensor monitor system pressure and temperature. If pressure is too low or temperature is too high, the APU is shut down.
• The generator is scavenged by elements in the lube module. Oil returning from the generator first passes through in-line screens. The pumps discharge oil into a generator scavenge filter and empties it into the reservoir. The generator scavenge filter has an impending bypass switch that causes the APU to shutdown if the filter becomes restricted.
• Oil from the forward bearings and gearbox returns to the reservoir by gravity. The turbine bearing area is scavenged by a single pump element. Oil passes through an inlet screen, through the pump and into the reservoir.
Lubrication System Summ
• Servicing provisions are on the reservoir case, as well as a sight gage.- There is an oil level sensor that signals the ECU. - In the bottom of the gearbox is a magnetic drain plug
that collects any metal particles for viewing in case of a suspected problem.
• Air and oil are separated by an air/oil separator. • The reservoir is vented to the exhaust section which
prevents over-pressurization of the reservoir during APU operation.
1
Notes:
ary Page 5-35
131-9B Line Maintenance Training Manual
Lubrication System Summ
Notes:
ary Page 5-36
131-9B Line Maintenance Training Manual
CHAPTER 6— FUEL SYSTEM
OBJECTIVES
Upon completion of this training section, you will be able to:• Locate and identify fuel system LRUs• Identify the purpose and operation of the fuel system
components.• Trace the flow of fuel through the fuel system.• Identify possible malfunctions related to the fuel system.
Fuel System Objec
Notes:
tives Page 6-1
131-9B Line Maintenance Training Manual
FUEL SYSTEM OVERVIEW
The APU fuel system is a fully automatic system controlled by theECU.
StartingDuring start, the fuel system provides the correct amount of fuelto support combustion and provides for smooth acceleration ofthe engine to full rated speed.
On-SpeedOnce rated speed is reached, fuel flow is modulated to meet thedemands of varying pneumatic and electrical loads while main-taining a constant speed.
Fuel SupplyFor proper operation, the aircraft system furnishes a stableamount of fuel at a pressure between 0 and 55 PSIG. The sys-tem also requires 24 VDC (range of 14-30 volts) power.
ShutdownDuring shutdown fuel flow is stopped by the fuel shutoff solenoid.
Fuel System Fuel System
Notes:
Overview Page 6-2
ATM717-024Fuel System Overview
Fuel System Overview
ATM717.02409/02
FuelControl Unit
FuelManifold
CombustorDrain Valve
Fuel FlowDivider
Fuel System Fuel System Overview Page 6-3
131-9B Line Maintenance Training Manual
FUEL SYSTEM COMPONENTS
The Fuel System consists of the following components:• Fuel Control Unit• Fuel Filters• Fuel Metering Assembly• Flow Divider Assembly
- Flow Divider Solenoid• Fuel Manifolds & Fuel Nozzles• Fuel Shutoff Solenoid• IGV Actuator Pressure Regulating Valve• Plenum Drain Valve• APU Drain Manifold
Fuel System Fuel System C
Notes:
omponents Page 6-4
ATM717-084Fuel System Components
Fuel System Components
ATM-717-084 (09/02)
• Fuel Control Unit
• Fuel Filters
• Fuel Metering Assembly
• Flow Divider Assembly
• Flow Divider Solenoid
• Fuel Manifolds & Fuel Nozzles
• Fuel Shutoff Solenoid
• IGV Actuator Pressure Regulating Valve
• Plenum Drain Valve
• APU Drain Manifold
Fuel System Fuel System Components Page 6-5
131-9B Line Maintenance Training Manual
FUEL CONTROL UNIT (FCU)
Identification and LocationThe FCU consists of the following:
• a high pressure fuel pump• seals• filters• fuel torque motor• flow meter• temperature sensor• fuel shutoff solenoid
The entire pump and control assembly is attached to the lubrica-tion module by means of a quick release V-band clamp.
Purpose and InterfaceThe fuel control unit supplies metered fuel to the flow divider inproportion to the signal received from the ECU.
Functional DescriptionThe FCU:
• is driven by an oil lubricated spline drive shaft.
• has a single electrical connector for fuel shutoff solenoid, fuel torquemotor feedback, and temperature.
• is designed to operate at supply pressures as low as 5 psi above true vapor pressure.
The gear pump is a positive displacement type.
Protection for the fuel pump system is provided by a safety reliefvalve (1150 PSI) (internal) which relieves pump pressure on allFCU shutdowns.
Fuel System Fuel System C
Maintenance TipFuel or oil seepage from the drain port is an indication that theseals are leaking internally. This condition warrants FCU replace-ment.
There is no “clogged filter” indicator.
Notes:
omponents Page 6-6
ATM717-014Fuel Control Unit
Fuel Control Unit
ATM717.01409/02
Fuel ControlUnit (FCU)
Lube ModuleAlignment Pin
Fuel SupplyTube Assembly
Fuel System Fuel System Components Page 6-7
131-9B Line Maintenance Training Manual
Fault IndicationFCU performance problems will cause the following protectiveshutdowns:
• No Flame• No Accel• Overtemperature• Overspeed• Underspeed
Starting Fuel Trim Schedule:
Table 1:
RPM Temperature
0 1750°F
10.3 1750°F
13 1650°F
20 1600°F
41 1520°F
51.2 1425°F
61.5 1425°F
71.7 1320°F
82 1200°F
90.2 1100°F
95 1070°F
98.4 1050°F
Fuel System Fuel System C
Notes:
omponents Page 6-8
ATM717-014Fuel Control Unit
Fuel Control Unit
ATM717.01409/02
Fuel ControlUnit (FCU)
Lube ModuleAlignment Pin
Fuel SupplyTube Assembly
Fuel System Fuel System Components Page 6-9
131-9B Line Maintenance Training Manual
FUEL FILTERS
Identification and LocationThe fuel filters include:
• a large capacity, replaceable element located at the inlet to the FCU (10-micron inlet filter).
• protective metal screens installed at the pump discharge (high pressure, non-bypassing type), shutoff valve, torque motor and flow divider valve locations.
Purpose and InterfaceThe filters trap normal fuel pump wear debris. The entire pumpdischarge flow passes through the filter.
Functional DescriptionThe metal screens installed at the pump discharge, shutoff valve,torque motor and flow divider valve locations are rated at 40microns nominal and 65 microns absolute.
The fuel filter housing and filter element are LRUs.
Maintenance Tip• The high pressure pump screen is replaceable without
removing the FCU.• The screens located at the fuel shutoff solenoid and flow
divider are of the same type.• All seals, filters, and internal components are compatible
with JP-4, JP-8, and Jet A fuels, and applicable additives.
Fuel System Fuel System C
NOTE: Recommended filter change is 3,500 APU hours or 3 years, whichever comes first.
NOTE: Fuel filters are designed to trap normal fuel pump wear debris.
Notes:
omponents Page 6-10
ATM717-015Fuel Filters
Fuel Filters
ATM717.01509/02
Filter Element
Filter Cap
Fuel System Fuel System Components Page 6-11
131-9B Line Maintenance Training Manual
FUEL METERING ASSEMBLY
Identification and LocationThe fuel metering assembly is located internally in the FCU.
Purpose and InterfaceThe ECU and fuel metering assembly control the APU start andacceleration.
Functional DescriptionThe fuel metering assembly meters fuel flow using a direct actingmetering valve (torque-motor). The metered fuel filter is a func-tion of ECU supplied current.
An increase in current increases fuel flow by enlarging the meter-ing area. A constant pressure drop across the torque motor iskept by the differential pressure regulator which senses fuel pres-sure upstream and downstream of the torque motor andbypasses excess fuel back to the pump inlet to maintain the dif-ferential pressure.
After leaving the torque motor, the metered flow passes throughthe integral flow meter and pressurizing valve, which keeps aminimum pressure down stream of the metering valve and tofeedback the flowrate amount to the ECU.
The fuel then travels through the fuel shutoff solenoid and out tothe fuel flow divider.
NOTE: Whenever a protective shutdown is initiated, the current to the torque-motor is automatically removed.
The Fuel Control Torque-motor is an integral part of the FCU andis not line adjustable or replaceable
Fuel System Fuel System C
Torque-Motor Current Versus Fuel Flow:
Table 6-1:
Milliampere lbs/hr
0 0
20 16
35 28
50 50
100 140
150 235
200 330
250 425
Notes:
omponents Page 6-12
ATM717-016Fuel Metering (Torque-Motor)Fuel Metering
Outlet Port
Fuel Inlet Port
Clevis
FCU TorquemotorMetering Valve
Fuel Metering (Torque-Motor)
ATM717.01611/02
Fuel System Fuel System Components Page 6-13
131-9B Line Maintenance Training Manual
FUEL FLOW DIVIDER & FLOW DIVIDER SOLENOID
Identification and LocationThe fuel flow divider is on the left side of the APU near the com-bustion chamber.
These are the main fuel flow divider components:
• Ball check valve• Inlet filter• Flow divider solenoid
PurposeThe fuel flow divider directs fuel to the primary and secondarymanifolds.
Functional DescriptionThe fuel flow divider gives fuel to the primary manifold duringstart of the APU.
At 25-40 percent speed or approximately 120 psi, the check valveinside the T fitting opens and supplies fuel to the secondary main-ifold, unless the flow divider solenoid is closed.
The fuel flow divider solenoid in normally open (de-energized). Itmakes sure fuel flows to the secondary manifold at the correcttime.
The ECU energizes the solenoid closed in the following conditions.
• During start from 7 to 30% speed.• Above 25,000 feet.• T2 less than 55°F
Fuel System Fuel System C
The flow divider solenoid also improves start capability in coldweather.
The ECU uses P2, T2, and speed signals to control the fuel flowdivider solenoid valve.
The flow divider assembly is considered an LRU.
Maintenance TipIf flow divider sequencing is incorrect, No Acceleration, No Flame,Overtemperature and Underspeed auto-shutdowns could occurwith NO faulty LRUs in ECU memory.
Notes:
omponents Page 6-14
ATM717-018Fuel Flow Assembly
Fuel Flow Assembly
ATM717.01809/02
Combustor
Primary Fuel FlowFlow Divider
Solenoid
Fuel FlowDivider
Fuel FlowDivider Secondary
Fuel Flow
Fuel Nozzles
Secondary
Fuel NozzlesPrimary
Fuel System Fuel System Components Page 6-15
131-9B Line Maintenance Training Manual
FUEL MANIFOLDS & FUEL NOZZLES
Identification and LocationThe two manifolds (primary and secondary) consist of ten (10)dual-orifice atomizers equally spaced and mounted on the com-bustor plenum.
Purpose and InterfaceThe primary and secondary fuel manifolds (2) route fuel to thefuel injector nozzles (10 dual orifice nozzles).
The fuel nozzles inject metered fuel into the combustor.
Functional Description• Fuel for ignition and initial acceleration is supplied by the
primary portion of the atomizers.• The fuel inlet has a filter screen to prevent contaminants
from entering the spray tip. An indexing pin positions the air shroud on the atomizer, and ensures accurate atomizer assembly in the engine.
• A hard coat is applied to the air shroud where it contacts the combustor to reduce wear.
• Combustor inlet air is introduced through the shroud to sweep the face of the spray tip to prevent carbon formation.
Maintenance TipThe combustor is bolted down to allow for removal and replace-ment of all fuel nozzles at the same time.
The inlet screens are removable for cleaning or replacement.
Fuel System Fuel System C
Notes:
omponents Page 6-16
ATM717-019Fuel Manifolds & Fuel Nozzles
Fuel Manifolds & Fuel Nozzles
ATM717.01909/02
FuelNozzle
Primary Secondary
Screens
Air Shroud
Nozzle Tip
Primary FuelManifold
SecondaryFuel Manifold
LocatingPin
Fuel System Fuel System Components Page 6-17
131-9B Line Maintenance Training Manual
FUEL SHUTOFF SOLENOID
Identification and LocationThe fuel shutoff solenoid is a three-way, normally closed, twoposition poppet valve. It is an integral part of the FCU and assuch, is not considered an LRU.
Purpose and InterfaceThe fuel shutoff solenoid directs metered fuel to the fuel flowdivider.
The fuel shutoff solenoid is energized by the ECU.
Functional DescriptionWhen the fuel shutoff solenoid is energized by the ECU, meteredfuel is directed through it and to the fuel flow divider.
When the solenoid is de-energized, APU operation is terminated(for either a protective or normal shutdown).
NOTE: If the fuel shutoff solenoid fails mechanically to open at approximately 7% speed, a No Flame auto-shutdown occurs and NO failed LRUs will be in ECU memory.
NOTE: If the fuel shutoff solenoid leaks fuel to the flow divider before approximately 7% speed, torching,
NOTE: Overtemperature or No Flame auto-shutdowns will occur without failed LRUs in ECU memory.
Fuel System Fuel System C
Notes:
omponents Page 6-18
ATM717-021Fuel Shutoff Solenoid
Fuel Shutoff Solenoid
ATM717.02111/02
Solenoid
Fuel System Fuel System Components Page 6-19
131-9B Line Maintenance Training Manual
IGV ACTUATOR PRESSURE REGULATING VALVE
Identification and LocationThe actuator pressure regulator is an integral part of the FCU.
Purpose and InterfaceThe pressure regulating valve provides the hydraulic pressureused to activate the inlet guide vane assembly and the surge con-trol valve.
Functional DescriptionThe valve maintains a fuel pressure of 250±25 psig to the inletof the IGV Actuator and Surge Control valve.
If pressure regulation is low or high, the Inlet Guide Vane Actua-tor could be faulted because it did not extend or retract to its pro-grammed position.
NOTE: The regulator is not line adjustable and is not considered to be an LRU.
Fuel System Fuel System C
Notes:
omponents Page 6-20
ATM717-022IGVA Pressure Regulator Valve
IGVA Pressure Regulator Valve
ATM717.02209/02
IGV Actuator/Surge Valve
Return
IGV Actuator/Surge Valve
Supply
ActuatorPressureRegulator
LubeModule
FuelPump
FuelSupply
Gearbox
LEGENDFUEL IN (LOW PRESSURE)PUMP DISCHARGE (HIGH PRESSURE)METERED FUELREGULATED PRESSUREACTUATOR RETURN
LRU FuelDrain TubeAssembly
IGV ReturnTube Assembly
IGV SupplyTube Assembly
Fuel SupplyTube Assembly
Fuel System Fuel System Components Page 6-21
131-9B Line Maintenance Training Manual
PLENUM DRAIN VALVE
Identification and LocationThe plenum drain valve is located at the lowest point in the ple-num.
Purpose and InterfaceA plenum drain valve (orificed) ensures complete drainage of fuelthat may accumulate in the combustor and turbine plenum fol-lowing an unsuccessful light off attempt (not attributed to fuel).Draining the excess fuel prevents a possible hot or torching start.
Maintenance Tip• An arrow on the valve body points in the direction of fuel
flow toward the overboard drain line.• Check to see if the valve is clean and unobstructed on a
scheduled basis. • Refer to the Boeing maintenance manual for more details.
NOTE: The valve is always open whether the APU is operating or not.
Fuel System Fuel System C
Notes:
omponents Page 6-22
ATM717-023Plenum Drain Valve
Plenum Drain Valve
ATM717.02309/02
CombustorDrain Valve
(Orificed Tube)
Fuel System Fuel System Components Page 6-23
131-9B Line Maintenance Training Manual
APU DRAIN MANIFOLD
Identification and LocationThere are four drains on the APU. Three of the drains are over-board drains that consist of two fuel drains and one oil drain. Thedrains are customer interfaced by the drain mast installedbeneath the inlet duct.
One drain (inlet duct) is internal to the airplane compartment.
Which is the forward, middle and aft drains.
Purpose and InterfaceThe forward drain detects degraded seal performance in the fuelcontrol unit (FCU), inlet guide vane (IGV) actuator, and surgecontrol valve (SCV) actuator.
The middle drain is used for detecting degraded load compres-sor main shaft seal performance.
The aft drain is used for disposing of excess fuel in the event ofan aborted start, and is also a means of draining the airplanemuffler.
Maintenance TipDuring normal operations, NO fuel is discharged from the aftdrain.
The leakage rates shown are acceptable for normal engine opera-tion after a minimum of five minutes at sustained APU speed.
Unit/Item Limit Max. Tolerance/Remarks:• Fuel/Lube Module cavity: 3 drops per minute allowed at
the FCU/lube moduledrain tell-tale witness drain.
Fuel System Fuel System C
• Inlet Guide Vane Actuator: 3 drops/minute allowed at the IGVA tell-tale witness drain.
• Oil Consumption: 8 cc/hr• Surge Control Valve (SCV): 3 drops/minute at the tell-
tale minute witness drain.A daily visual inspection check for leakage at the APU drain mani-fold should be done by maintenance personnel.
Leakage more than the limits or a sudden leakage increase, mustbe monitored frequently and/or necessary maintenance sched-uled.
Notes:
omponents Page 6-24
ATM717-059APU Drain Manifold
APU Drain Manifold
ATM717.05909/02
Load CompressorSeal Drain
Combustor Case/Eductor, Muffler
DrainFCU/SCV/IGVA
Drain
BOTTOM VIEW
FWD
Fuel System Fuel System Components Page 6-25
131-9B Line Maintenance Training Manual
FUEL SYSTEM FLOW
The aircraft fuel system supplies the APU with low-pressure fuel.• Fuel is passed through an inlet filter on the fuel control
unit.• After the filter, the fuel is sent to a two-stage pump and
actuator supply regulator. This fuel is used to operate the inlet guide vane and surge control valve actuators.
• After passing through the pump, the fuel is sent to a high-pressure fuel filter and the torque motor (TM). The torque motor is controlled by signals from the ECU.
• Fuel leaving the TM is now metered fuel which is used to operate the APU. The metered fuel flows past a temperature sensor and integral flow divider. The resulting signals are used to adjust flow rates for starting the APU in cold conditions and altitude.
• The fuel then flows to the fuel shutoff solenoid. - When energized at 7% speed, it allows fuel to flow to
the flow divider and flow divider solenoid. - When the ECU receives an OFF signal and the APU has
completed a cool-down cycle, the fuel shutoff solenoid closes and the APU shuts down.
• The flow divider and flow divider solenoid distribute the fuel between primary flow and secondary fuel manifolds.- Primary flow is for starting the APU and secondary flow
is for acceleration and on-speed operating conditions. - The flow divider solenoid is controlled by the ECU.
• Attached to the manifolds are 10 fuel nozzles. The nozzles inject fuel into the combustion chamber for APU operation.
• On the bottom of the outer combustion case is a plenum drain valve. It is used to drain the excess fuel from the combustion chamber in case of a no start condition.
Fuel System Fuel Syste
Notes:
m Flow Page 6-26
ATM717-017Fuel System Flow
Fuel System Flow
ATM717.01709/02
ActuatorReturn
ElectricalConnector
MeteringModule
ActuatorSupply
ActuatorPressureRegulator
P2Pressure
Tap
FlowmeterResolver
RTD
FlowmeterPressurizing
Valve
3-WayShutoff
SolenoidN.C.
MeteredFlow
Discharge
Orifice
DifferentialPressureRegulator
Bypass Bleed(Double Screened)
FuelSupply
Inlet FuelFilter Element
High PressureFuel Pump
SealDrain
LubeModule
PumpDriveSpline
ShaftSeals
PumpReliefValve
HighPressureFuel Filter
LEGENDFuel In (Low Pressure)
Pump Discharge(High Pressure)
Metered Fuel
Regulated Pressure
Actuator Return
Fuel System Fuel System Flow Page 6-27
SUMMARY
Now that you have completed this section, you should be able to:
• Locate and identify fuel system LRUs• Identify the purpose and operation of the fuel system
components.• Trace the flow of fuel through the fuel system.• Identify possible malfunctions related to the fuel system.
What are the fuel system LRUs?• Fuel Control Unit• Fuel Filters• Flow Divider Assembly
- Flow Divider Solenoid• Fuel Manifolds & Fuel Nozzles• Plenum Drain Valve• APU Drain Manifold
What is the purpose of each LRU?• Fuel Control Unit: supplies metered fuel to the flow
divider in proportion to the signal received from the ECU.• Fuel Filters: trap normal fuel pump wear debris. The
entire pump discharge flow passes through the filter.• Fuel Metering Assembly: through the ECU controls APU
start and acceleration.• Flow Divider Assembly/Flow Divider Solenoid: distributes
the fuel between primary flow and secondary fuel manifolds.
• Fuel Manifolds & Fuel Nozzles: the manifolds route fuel to the fuel injector nozzles; the fuel nozzles inject metered fuel into the combustor.
• Fuel Shutoff Solenoid: directs metered fuel to the fuel flow divider.
• IGV Actuator Pressure Regulating Valve: provides the hydraulic pressure used to activate the inlet guide vane assembly and the surge control valve.
Fuel System Summ
• Plenum Drain Valve: ensures complete drainage of fuel that may accumulate in the combustor and turbine plenum during an unsuccessful start.
• APU Drain Manifold: - The forward drain detects degraded seal perfor-
mance in the fuel control unit (FCU), inlet guide vane (IGV) actuator, and surge control valve (SCV) actuator.
- The middle drain is used for detecting degraded load compressor main shaft seal performance.
- The aft drain is used for disposing of excess fuel in the event of an aborted start, and is also a means of drain-ing the airplane muffler.
Describe the flow of fuel through the engine.• Fuel is passed through an inlet filter on the fuel control
unit.• After the filter, the fuel is sent to a two-stage pump and
actuator supply regulator. This fuel is used to operate the inlet guide vane and surge control valve actuators.
Notes:
ary Page 6-28
• After passing through the pump, the fuel is sent to a high-pressure fuel filter and the torque motor (TM). The torque motor is controlled by signals from the ECU.
• Fuel leaving the TM is now metered fuel which is used to operate the APU. The metered fuel flows past a temperature sensor and integral flow divider. The resulting signals are used to adjust flow rates for starting the APU in cold conditions and altitude.
• The fuel then flows to the fuel shutoff solenoid. - When energized at 7% speed, it allows fuel to flow to
the flow divider and flow divider solenoid. - When the ECU receives an OFF signal and the APU has
completed a cool-down cycle, the fuel shutoff solenoid closes and the APU shuts down.
• The flow divider and flow divider solenoid distribute the fuel between primary flow and secondary fuel manifolds.- Primary flow is for starting the APU and secondary flow
is for acceleration and on-speed operating conditions. - The flow divider solenoid is controlled by the ECU.
• Attached to the manifolds are 10 fuel nozzles. The nozzles inject fuel into the combustion chamber for APU operation.
• On the bottom of the outer combustion case is a plenum drain valve. It is used to drain the excess fuel from the combustion chamber in case of a no start condition.
Fuel System Summ
Notes:
ary Page 6-29
131-9B Line Maintenance Training Manual
Fuel System Summ
Notes:
ary Page 6-30
131-9B Line Maintenance Training Manual
CHAPTER 7—PNEUMATIC SYSTEM
OBJECTIVES
Upon completion of this training section, the student will:
• Locate and identify the pneumatic system LRUs.• Identify the purpose and operation of the pneumatic
system components.• Identify possible malfunctions related to the pneumatic
system.
Pneumatic System Objec
Notes:
tives Page 7-1
131-9B Line Maintenance Training Manual
OVERVIEW
The pneumatic system provides compressed air to the (undervarying load conditions) to prevent surging of the APU load com-pressor.
The pneumatic system is comprised of a:• PT Sensor• P2 Sensor• DP Sensor• Inlet guide vane actuator (IGV)• Inlet temperature sensor (T2)• Surge Control Valve
Pneumatic System Overv
Notes:
iew Page 7-2
ATM717-039Pneumatic System Schematic
LEGEND
Pneumatic System Schematic
ATM717.03909/02
Inlet Temperature Sensor (T2)
PowerSection
Inlet Air Flow
LVDT
DPSensor
PTSensor
Opening Piston
ClosingSpring
AirFlow
ToECU
SCV
TM
ToECU
Fuel Out
Fuel In
Gearcase Vent AirElectrical SignalLoad CompressorBleed AirAPU CompartmentCooling AirAPU Inlet AirExhaust Air
Air/OilSeparator
Fuel In
FuelOut
OilCooler
IGVAInlet PressureSensor (P2) Oil In
Oil Out
CompartmentAir
LoadCompressor
Surge Bleed Air Exhaust
Total PressureProbe (PT)
ExhaustEductor
VisualPositionIndicator
Closed
Closed
Open Open
PositionSwitch
Open
Closed
Open
Close
ECUBAV
Solenoid
Static PressureSensing Ports
Pneumatic System Overview Page 7-3
131-9B Line Maintenance Training Manual
PNEUMATIC SYSTEM COMPONENTS
The pneumatic system consists of:• Surge Control Valve• Flow Sensor Assembly
- PT Sensor- DP Sensor- P2 Sensor
• Inlet Temperature Sensor• Bleed Air Valve• Inlet Guide Vane Assembly
Pneumatic System Pneumatic Syste
Notes:
m Components Page 7-4
ATM717-085Pneumatic System Components
Pneumatic System Components
ATM717.085 (09/02)
• Surge Control Valve
• Flow Sensor Assembly
• PT Sensor
• DP Sensor
• P2 Sensor
• Flow Sensor Probes
• Inlet Temperature Sensor
• Bleed Air Valve
• Inlet Guide Vane Assembly
Pneumatic System Pneumatic System Components Page 7-5
131-9B Line Maintenance Training Manual
SURGE CONTROL VALVE (SCV)
Identification and LocationThe surge control valve (SCV) is a butterfly type valve. The SCVactuator is on the top of the valve. A two-stage servo valve con-trols the actuator. A visual indicator on the valve gives the posi-tion of the valve.
The SCV is located in the surge bleed duct on the right side of theAPU.
Purpose and InterfaceThe ECU controls a torque motor on the servo valve. This motorsends high pressure fuel from the APU fuel system to open orclose the surge control valve. The valve moves between 10degrees (open) and 90 degrees (closed). A linear variable differ-ential transformer (LVDT) supplies valve position feedback to theECU.
The surge control valve (SCV) releases air from the load compres-sor. The SCV makes sure there is a minimum flow of air throughthe load compressor. This prevents a surge. If a surge doesoccur, the SCV opens to help the load compressor recover.
The surge margin set point is the minimum quantity of correctedair that should flow through the load compressor to prevent loadcompressor surge. The ECU calculates the corrected airflow andthe surge margin set point. The corrected airflow is the quantityof air that flows through the load compressor. The ECU uses totalpressure (PT) and differential pressure (DP) to calculate the cor-rected airflow. The ECU uses the following inputs to calculate thesurge margin set point:
• Inlet temperature (T2)• IGV position• Bleed mode
Pneumatic System Pneumatic Syste
• Air/ground
Air that flows through the surge control valve goes overboardthrough the exhaust duct.
Notes:
m Components Page 7-6
ATM717-040Surge Control Valve
Surge Control Valve
ATM717.04011/02
Surge ControlValve
Pneumatic System Pneumatic System Components Page 7-7
131-9B Line Maintenance Training Manual
FLOW SENSOR ASSEMBLY
Identification and LocationThe flow sensor assembly (P2, PT and DP) consists of staticpressure taps located in the load compressor diffuser and a totalpressure probe (basically a shaped tube) in the duct between thediffuser and bleed air valve.
Purpose and InterfaceAll 3 pressure sensors (transducers) (P2, PT, and DP) changepressure into an electrical signal and transmit these values to theECU to control:
• fuel scheduling during APU starts• surge control valve operations• inlet guide vane positions
The total pressure sensor (PT) measures load compressor dis-charge pressure.
The delta pressure sensor (DP) measures the difference betweentotal and static pressures.
The ambient pressure sensor (P2) measures inlet pressure.
NOTE: The flow sensors real-time data can be viewed on the flightdeck CDU panel, under APU BITE TEST.
NOTE: The ECU compensates for any possible drift in the Delta P sensor zero point by adding or subtracting a compensating offset if a non zero Delta P is detected in Pre-Start BIT.
Pneumatic System Pneumatic Syste
Notes:
m Components Page 7-8
ATM717-042Flow Sensor Assembly
REAL TIME PARAMETERS 1/4
SPEEDEGTIGV POSITIONSCV POSITIONDELTA PRESSTOTAL PRESSINLET PRESSINLET TEMPFUEL TMCFUEL FLOW<INDEX
000.0 % 20.5 C 00.0 DEG 10.0 DEG 0.0 PSID 14.7 PSIA 14.7 PSIA 20.5 C 0.0 MA 00.0 PPH
APU BITE TEST
Flow Sensor Assembly
ATM717.04209/02
Pressure AmbientSensor (P2)
Delta PressureSensor ( ∆P)
CDU
Pressure TotalSensor (PT)
Pneumatic System Pneumatic System Components Page 7-9
131-9B Line Maintenance Training Manual
Functional Description• The P2 and PT sensing probes sample the air
pressure developed by the load compressor and route to the electrical sensors. The sensors translate the pressure input into an electrical signal that is transmitted to the ECU.
• The ECU interprets the signals from the PT and DP transducers, as well as the altitude input (P2) and inlet guide vane position (LVDT).
• After interpreting these parameters, the ECU provides the correct command signal to the Surge Control valve to modulate it more open or closed in order to provide a constant airflow through the compressor during all loading conditions.
PT and P2 signals are sent to the flow sensor manifoldwhich directs the pressure to the total and differential pressuresensors.
In the event of a failure, the ECU allows safe electric-load opera-tion by holding the SCV open and the IGVs closed. This gives pri-ority to electric (shaft load) operation at the expense of bleed loadin the event of a surge system malfunction.
Pneumatic System Pneumatic Syste
Notes:
m Components Page 7-10
ATM717-077Flow Sensor Schematic
REAL TIME PARAMETERS 1/4SPEEDEGT
IGV POSITIONSCV POSITIONDELTA PRESSTOTAL PRESSINLET PRESSINLET TEMPFUEL TMCFUEL FLOW
<INDEX
000.0 % 20.5 C
00.0 DEG 10.0 DEG 0.0 PSID 14.7 PSIA
14.7 PSIA 20.5 C
0.0 MA 00.0 PPH
CDU
5 R5 R
APU Bite Test
Flow Sensor Schematic
ATM717.07709/02
(LVDT)
BleedAir
Valve
One-wayCheckValve
SurgeControlValve
PT Transducer
DP Transducer
To APUExhaust
Pipe
To AircraftBleed Duct
PressureTotalProbe
PressureStaticProbe
TM
LoadCompressor
Diffuser
Load CompressorDischarge Air
Pneumatic System Pneumatic System Components Page 7-11
131-9B Line Maintenance Training Manual
INLET TEMPERATURE SENSOR (T2)
Identification and LocationThe inlet temperature sensor (T2) is a resistance temperaturetype detector located on the bottom of the APU compressor ple-num.
Purpose and InterfaceThe inlet temperature sensor supplies inlet air temperature data(T2) to the ECU. This data is used for:
• Fuel Control (during APU starting)• IGV Control (during bleed air usage)• SCV Control (>95% APU speed)• EGT trim schedule (ECS and MES modes)
Functional Description• When air temperature into the APU inlet compressor
changes, the resistance changes in the sensor.• The ECU senses this change in resistance and adjusts the
APU operation due to that temperature change.
NOTE: The ECU also sends the temperature to the control display unit (CDU) in the flight compartment where it can be viewed by the operator.
The Inlet Temperature Sensor is an LRU.
Pneumatic System Pneumatic Syste
Notes:
m Components Page 7-12
ATM717-044Inlet Temperature Sensor (T2)
APU B ITE TESTREAL TIME PARAMETERS 1/4
SPEEDEGTIGV POSITIONSCV POSITIONDELTA PRESSTOTAL PRESSINLET PRESSINLET TEMPFUEL TMCFUEL FLOW<INDEX
100.0 % 650 C 80.1 DEG 90.0 DEG 6.2 PSID 50.5 PSIA 13.8 PSIA 20.5 C 139 MA 249 PPH
Inlet Temperature Sensor (T2)
ATM717.04409/02
T2 Sensor(Temperature Ambient) ECU
CDU
Pneumatic System Pneumatic System Components Page 7-13
131-9B Line Maintenance Training Manual
BLEED AIR VALVE (BAV)
Identification and LocationThe bleed air valve is a pneumatically actuated, open and closedbutterfly valve located between the bleed air duct and compressordischarge duct.
PurposeThe Bleed Air Valve (BAV) controls bleed airflow to the airplane.
Functional Description• The BAV is normally in the closed position. Load
compressor bleed air, controlled by a solenoid, provides the power for valve opening.
• The ECU energizes the solenoid mechanism to open the valve when the APU bleed switch (P5 Pneumatic Control Panel) is in the ON position and the APU speed is greater than 95 percent.
Pneumatic System Pneumatic Syste
Notes:
m Components Page 7-14
ATM717-043Bleed Air Valve
Bleed Air Valve
ATM717.04311/02
MechanicalPositionIndicator
Bleed AirValve
CLOSED
OP
EN
OP
EN
Pneumatic System Pneumatic System Components Page 7-15
131-9B Line Maintenance Training Manual
INLET GUIDE VANE (IGV) ASSEMBLY
Identification and LocationThe IGV assembly consists of 16 vanes located radially at the loadcompressor inlet.
Purpose and InterfaceThe IGV assembly controls the air flow to the load compressor.The IGV consists of the:
• IGV Actuator• Linear Variable Differential Transformer (LVDT)
Functional DescriptionThe vanes are supported at one end and are driven by gear seg-ments attached to each vane. The gear segments mesh with acylindrical rack to synchronize vane position.
During an APU start, the IGVs are held at 22 degrees for altitudesabove 25,000 feet. If altitude is below 15,000 feet, the IGVs areheld at 15 degrees up to 60 percent speed and then opened to 22degrees.
Bleed Air Demands:• No bleed• Duct Pressurization• Main Engine Start• Air Conditioning System
Pneumatic System Inlet Guide Vane
NOTE: IGV position is a function of P2, T2 and load demand, and is controlled by the ECU.
IGV ActuatorThe IGV actuator regulates the load compressor discharge air bypositioning the vanes in response to an electrical signal from theECU.
LVDTThe Linear Variable Differential Transformer (LVDT) provides con-tinuous IGV actuator position during APU operation. The LVDT isinternally mounted to the IGV actuator and is powered by theECU.
• The IGV position is seen on the CDU/APU Input Monitoring page.
Notes:
(IGV) Assembly Page 7-16
ATM717-004Inlet Guide Vane (IGV) Assembly
Inlet Guide Vane (IGV) Assembly
ATM717.00409/02
IGV AccessCover
Linkage
Vanes (16)
Bolts (3)Attachment
Bolt
IGV Actuator
L/C BoroscopePort
Pneumatic System Inlet Guide Vane (IGV) Assembly Page 7-17
131-9B Line Maintenance Training Manual
SUMMARY
Now that you have completed this section, you should be able to:
• Locate and identify pneumatic system LRUs• Identify the purpose and operation of the pneumatic
system components.• Identify possible malfunctions related to the pneumatic
system.
What are the pneumatic system LRUs?• Surge Control Valve• Flow Sensor Assembly
- PT Sensor- DP Sensor- P2 Sensor
• Inlet Temperature Sensor• Bleed Air Valve• Inlet Guide Vane Assembly
What is the purpose of each LRU?• Surge Control Valve: prevents a surge by releasing air
from the load compressor to ensure there is a minimum flow of air through the load compressor.
• Flow Sensor Assembly- PT Sensor: measures load compressor discharge pres-
sure.- DP Sensor: measures the difference between total and
static pressures.- P2 Sensor: measures inlet pressure.
• Inlet Temperature Sensor: supplies inlet air temperature data to the ECU.
Pneumatic System Summ
• Bleed Air Valve: controls bleed airflow to the airplane.• Inlet Guide Vane Assembly: controls air flow to the load
compressor.
Notes:
ary Page 7-18
131-9B Line Maintenance Training Manual
CHAPTER 8—ELECTRICAL ACCESSORIES
OBJECTIVES
Upon completion of this training section, you will be able to:• Locate and identify the electrical accessory LRUs.• Explain the purpose of each electrical accessory
component.• Identify possible causes of electrical accessory
malfunctions.
Electrical Accessories Objec
Notes:
tives Page 8-1
131-9B Line Maintenance Training Manual
OVERVIEW
The APU electrical control system consists of electrical accessoriesthat work in conjunction with the ECU. Together the electricalaccessories and ECU sense and control the functions required tosafely and reliably start and monitor the APU.
Electrical Accessories Overv
Notes:
iew Page 8-2
ATM717-Electrical Accessories Overview
Electrical Accessories Overview Page 8-3
131-9B Line Maintenance Training Manual
ELECTRICAL ACCESSORIES COMPONENTS
Electrical accessories components include:• Start Power Unit• Start Converter Unit (SCU)• Electronic Control Unit (See Chapter 3)• APU Starter-Generator• Ignition Unit• EGT Thermocouples• Speed Sensor• Data Memory Module (DMM)
Electrical Accessories Electrical Accesso
Notes:
ries Components Page 8-4
ATM717-086Electrical Accessory Components
Electrical Accessory Components
ATM717-086 (09/02)
• Start Power Unit• Start Converter Unit• Electronic Control Unit• Starter-Generator• Ignition Unit• EGT Thermocouple Rakes• Speed Sensor (Monopole)• Data Memory Module (DMM)
Electrical Accessories Electrical Accessories Components Page 8-5
131-9B Line Maintenance Training Manual
START POWER UNIT (SPU)
Identification and LocationThe start power unit (SPU) is located in the EE compartment onthe E2-2 shelf.
Purpose and InterfaceThe start power unit changes 28 VDC or 115 VAC electrical powerto 270 VDC power for the start converter unit (SCU). Theswitched hot battery bus or the transfer bus number 1 suppliespower to the SPU.
Functional DescriptionThe operational flow is as follows:
• The ECU sends a signal to the SCU when the air inlet door is fully open.
• The Start Converter Unit (SCU) tells the SPU to supply 270 VDC power.
• The SCU then changes the 270 VDC to AC power for the operation of the starter-generator.
• At 70% speed, the ECU removes the start signal from the SCU. With the start signal off, the SCU and SPU remove power from the starter-generator.
NOTE: The maximum duty cycle for the SPU and SCU is three starts, one after the other, followed by a 15 minute cool down period. More starts are possible after the SCU and SPU are cool.
Electrical Accessories Electrical Accesso
Notes:
ries Components Page 8-6
ATM717-066Start Power Unit
EE Compartment (Looking Aft)
Start Power Unit (E2-2)
115 VAC Transfer Bus 1Or Switched Hot
Battery Bus
Start Power Unit
ATM717.06609/02
Electrical Accessories Electrical Accessories Components Page 8-7
131-9B Line Maintenance Training Manual
START CONVERTER UNIT (SCU)
Identification and LocationsThe start converter unit (SCU) is located on the E2 rack in the EEcompartment.
Purpose and InterfaceThe SCU:
• operates with the APU generator control unit (AGCU) to control and regulate APU starter-generator power.
• makes the starter-generator function like a motor to turn the APU during starting.
• Changes 270 VDC from the SPU to AC power to energize the starter-generator during starting (through the SCU internal contactor)
• Sends fault data to the APU ECUThe APU generator control relay (AGCR) and the starter-genera-tor voltage regulator are inside the SCU.
Functional DescriptionThe operational flow is as follows:
• The ECU sends a signal to the SCU when the air inlet door is fully open.
• The SCU tells the SPU to supply 270 VDC power.• The SCU then changes the 270 VDC to AC power for the
operation of the starter-generator.• At 70% speed, the ECU removes the start signal from the
SCU.• With the start signal off, the SCU and SPU remove power
from the starter-generator.
Electrical Accessories Electrical Accesso
NOTE: The maximum duty cycle for the SPU and SCU is three starts, one after the other, followed by a 15 minute cool down period. More starts are possible after the SCU and SPU cool.
Notes:
ries Components Page 8-8
ATM717-078Start Converter Unit (SCU)
Start Converter Unit (E2-2)
EE Compartment (Looking Aft)
ECU (Aft Cargo)
ATM717.07809/02
Start Converter Unit
Electrical Accessories Electrical Accessories Components Page 8-9
131-9B Line Maintenance Training Manual
OperationThe voltage regulator and the APU generator control relay (AGCR)give excitation to the starter-generator. The voltage regulatorcontrols the amount of excitation and frequency of excitation tocontrol generator output voltage. The AGCR completes or opensthe circuit for excitation power.
The APU generator control unit (AGCU) controls the operation(on/off) of the voltage regulator and AGCR position. The AGCUsends a “voltage- regulator- enable signal” (turn on signal) to theSCU when you put an APU generator switch to the on position ifthe APU is ready to load. The AGCR also closes.
The starter-generator permanent magnet generator (PMG) is thepower source for the voltage regulator. The AGCU protection cir-cuits use the PMG output to monitor starter-generator frequencyoutput.
The voltage regulator and the AGCU monitor the voltage of eachphase at point between the starter-generator and the auxiliarypower breaker (APB). The voltage regulator uses this informationto control excitation. The AGCU uses this information for systemprotection purposes.
ProtectionThe AGCU removes the “voltage-regulator-enable signal” andopens the AGCR when the AGCU protection circuits find an electri-cal parameter not within limits.
The AGCU sends a fault signal to the SCU if a starter-generatorhigh voltage or low voltage condition happens.
The SCU sends this data to the APU ECU. This data is displayed onthe control display unit (CDU) in the flight compartment.
Electrical Accessories Electrical Accesso
Notes:
ries Components Page 8-10
ATM717-067SCU Interface
SCU Interface
ATM717.06709/02
ToBTB1,BTB2
SPU
APU StartSW (P5)
VoltageSense
PWRSupply
VoltageRegulatorand AGCR
Enable/Close
SCU
ControlCircuits
ProtectionCircuits
FaultData
APU ECU CDU (2)
RotorPMG
RotorExciter
Main GenRotor
LCT APB
To AGCU
StatorMain Gen
PMGStator
NCT
To AGCU
DC To ACConverter Cont
Starter-Generator
AGCU
APUCont
P6
28 VDCSW HotBat. Bus
Electrical Accessories Electrical Accessories Components Page 8-11
131-9B Line Maintenance Training Manual
STARTER-GENERATOR
Identification and LocationThe brushless AC starter-generator (which weighs 54.5 lbs.) is asalient-pole synchronous type incorporating three devices: a per-manent-magnet generator, exciter generator, and a main AC gen-erator. They share a common shaft and housing.
It is located on the upper right side of the APU gearbox and isattached with eight bolts.
Purpose and InterfaceThe starter-generator supplies the initial rotation of the APU dur-ing the start cycle. It also supplies 90 KVA, AC electrical power tothe aircraft while on the ground or in flight.
The starter-generator functions are controlled by the SCU, whichreceives 270 volts from the SPU and becomes operational inresponse to the start command (start relay signal) from the APUECU.
During the generate mode, the PMG power from the APU starter-generator is used to supply power to the starter-generator volt-age regulator.
The Starter-Generator is considered an LRU.
Maintenance Tip• If oil is leaking out from bottom of starter/generator, the
seal plate needs replacing.• There is an o-ring installed on the generator shaft. If the
O-ring is missing or cut, excessive heat accumulation to the generator will result.
Electrical Accessories Electrical Accesso
Notes:
ries Components Page 8-12
ATM717-047Starter-Generator
Starter-Generator
ATM717.04709/02
Starter/ Generator
Electrical Accessories Electrical Accessories Components Page 8-13
131-9B Line Maintenance Training Manual
IGNITION UNIT
Identification and LocationThe ignition unit is a single-output, dc powered unit. The output isa high-tension oscillatory-type ignition pulsing 2 to 11 times asecond.
The ignition unit bolts to the lower part of the turbine plenum.
Purpose and InterfaceThe ignition unit provides the APU with 1.0 joules deliveredenergy at 18K volts to the igniter at a minimum spark rate of 2sparks per second.
The ignition system operates on voltages from 14-36 VDC, alti-tudes from sea level to 41,000 feet.
The ignition unit, cable and plug are LRUs.
CAUTION: VOLTAGE PRODUCED BY THE IGNITION SYSTEM IS LETHAL. CAUTION SHOULD BE OBSERVED WHEN WORKING WITH THE SYSTEM.
NOTE: Ignition system problems not detected by the ECU will give the operator No Acceleration or No Flame auto-shutdowns.
NOTE: The ignition unit is energized in the 0-60% RPM range.
Electrical Accessories Electrical Accesso
Notes:
ries Components Page 8-14
ATM717-048Ignition Unit System
Ignition Unit System
ATM717.04809/02
Igniter Plug
IgniterPlug Lead
Ignition Unit
Electrical Accessories Electrical Accessories Components Page 8-15
131-9B Line Maintenance Training Manual
EGT THERMOCOUPLES
Identification and LocationThe EGT thermocouples are 2 closed-beaded, dual element,chromel-alumel (K-type) thermocouples, located in the APUexhaust duct.
Purpose and InterfaceThe EGT thermocouples provide EGT temperature input to theECU. Input signals control fuel flow based on acceleration to pre-vent over-temperature conditions.
Functional DescriptionEach thermocouple is separately sensed and conditioned by theECU. The ECU selects the highest reading of both rakes, so thatthe loss of one rake will not influence APU operation. This defersmaintenance action and increases dispatch reliability.
BITE circuitry allows detection of an open thermocouple duringprestart checks.
• If both thermocouple rakes fail, a start is inhibited.• If both thermocouple rakes fail open, or both
thermocouple measurement channels fail, while the APU is active, a shutdown is initiated.
• If one of the two thermocouples fail, the APU will start and run normally; an EGT TC1 (or EGT TC2)
LRU failure is stored in the ECU.
Maintenance TipThe individual thermocouples may be changed separately withoutdisturbing the system.
Electrical Accessories Electrical Accesso
NOTE: The actual temperature of the APU can be viewed on the flightdeck CDU panel, under APU BITE TEST.
Notes:
ries Components Page 8-16
ATM717-045EGT Thermocouples
REAL TIME PARAMETERS 1/4
APU BITE TEST
SPEEDEGTIGV POSITIONSCV POSITIONDELTA PRESSTOTAL PRESSINLET PRESSINLET TEMPFUEL TMCFUEL FLOW<INDEX
000.0 % 20.5 C
00.0 DEG 10.0 DEG 0.0 PSID
14.7 PSIA 14.7 PSIA
20.5 C 0.0 MA
00.0 PPH
LOW
HIGH
INT
L WIPERPARK10
EGT8
6
4 2
FAULT OVERSPEED
LOW OILPRESSUREMAINT
EGT Thermocouples
ATM717.04509/02
Exhaust Gas TemperatureThermocouples (2)
CDU
P5-4 Panel
(OR)
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131-9B Line Maintenance Training Manual
SPEED SENSOR
Identification and LocationThe speed sensor is a magnetic, non-contact, variable-reluctancesensor located near a gear inside of the gearbox.
Purpose and InterfaceThe speed sensor monitors mechanical motion, and sends anelectronic signal to the ECU proportional to the motion sensed.
Functional DescriptionThe speed sensor senses the gear tooth passage as the APU shaftrotates. Frequency is used by the ECU to compute APU speed.
The air gap between the stationary sensor and the moving teethof the gear will be fixed at a gap of 0.015±0.010 inch.
Its dual-coil design provides two independent speed signal to theECU for redundancy.
The speed sensor is an LRU.
Maintenance TipThe speed sensor can be removed and replaced, without measur-ing. No shimming is required.
If the APU has an overspeed condition (>106%), an amber over-speed light illuminates on the P5 flightdeck panel.
Electrical Accessories Electrical Accesso
NOTE: When the overspeed light comes on, the master caution and APU annunciator light on the P7 panel also comes ON.
NOTE: The master caution and APU annunciator lights tell the pilot/ground crew that the APU has a problem.
Notes:
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ATM717-046Speed Sensor
REAL TIME PARAMETERS SPEEDEGTIGV POSITIONSCV POSITIO NDELTA PRESSTOTAL PRESSINLET PRESSINLET TEMPFUEL TMCFUEL FLOW<INDEX
000.0 % 20.5 C
00.0 DEG 10.0 DEG 0.0 PSID 14.7 PSIA 14.7 PSI A
20.5 C 0.0 M A
00.0 PPH
1/4
Speed Sensor
ATM717.04609/02
CDU
Speed Sensor (Monopole)
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131-9B Line Maintenance Training Manual
DATA MEMORY MODULE (DMM)
Identification and LocationThe Data Memory Module (DMM) is an engine mounted (left sideof inlet plenum), non-volatile memory device.
Purpose and Interface The DMM stores information regarding the health monitoring andlife usage of the APU and is powered from the aircraft battery busvia the ECU.
The DMM interfaces with the ECU via a serial link and stores thefollowing information:
• APU serial number and model number• APU operating hours and starts• APU LCF (Low Cycle Fatigue) and creep life• APU accumulated aborted starts
The CDU “menu” handling is according to the Boeing SCD with allcommunication via an ARINC 429 low-speed data bus.
Functional DescriptionThe DMM comes with the APU serial number programmed.
At power-up, the software reads the DMM test pattern and per-forms the following:
• If numbers agree, power-up initialization is continued• If different, the ECU record is updated from the DMM.• Upon completion of an APU cool down cycle, the DMM is
automatically updated from the ECU.
APU data is also stored in the ECU in case of DMM failure.
Electrical Accessories Electrical Accesso
DMM ReplacementThe the ECU is replaced, the DMM retains all the APU data andautomatically re-initializes the new ECU with the old accumulatedAPU data.Once recognized, the ECU records in memory that a DMM changehas occurred. The new DMM is then loaded with all the totaledAPU data that is stored in the ECU. The recent DMM change mes-sage is retained until the ECU is interrogated and message erasedvia command from the ARINC 429 data bus.
NOTE: Replacement DMMs are delivered with all zeros stored in their memory, hence, they are easily recognizable by the ECU as new or recycled units.
Notes:
ries Components Page 8-20
ATM717-049Data Memory Module (DMM)
Data Memory Module (DMM)
ATM717.04909/02
Data MemoryModule (DMM)
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131-9B Line Maintenance Training Manual
SUMMARY
Now that you have completed this section, you should be able to:
• Identify and locate the electrical accessory LRUs.• Explain the purpose of each electrical accessory
component.• Identify possible causes of electrical system malfunctions.
What are the electrical Accessory Components?The electrical accessories components are:
• Start Power Unit (located in the EE compartment on the E2-2 shelf)
• Start Converter Unit (located on the E2 rack in the EE compartment)
• Electronic Control Unit (See Chapter 3)• Starter-Generator (located on the upper right side of the
APU gearbox)• Ignition Unit (bolts to the lower part of the turbine
plenum)• EGT Thermocouples (located in the APU exhaust duct)• Speed Sensor (located near a gear inside of the gearbox)• Data Memory Module (located on the left side of inlet
plenum)
What is the purpose of each electrical accessory component?• Start Power Unit: changes 28 VDC or 115 VAC electrical
power to 270 VDC power for the start converter unit
Electrical Accessories Summ
• Start Converter Unit: - operates with the APU generator control unit (AGCU) to
control and regulate APU starter-generator power.- makes the starter-generator function like a motor to
turn the APU during starting. - Changes 270 VDC from the SPU to AC power to ener-
gize the starter-generator during starting (through the SCU internal contactor)
- Sends fault data to the APU ECU• Electronic Control Unit (See Chapter 3)• APU Starter-Generator: supplies the initial rotation of the
APU during the start cycle. It also supplies 90 KVA, AC electrical power to the aircraft while on the ground or in-flight.
Notes:
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• Ignition Unit: provides the APU with 1.0 joules delivered energy at 18K volts to the igniter at a minimum spark rate of 2 sparks per second
• EGT Thermocouples: provide EGT temperature input to the ECU
• Speed Sensor: monitors mechanical motion, and sends an electronic signal to the ECU proportional to the motion sensed
• Data Memory Module: stores information regarding the health monitoring and life usage of the APU and is powered from the aircraft battery bus via the ECU.
Electrical Accessories Summ
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Electrical Accessories Summ
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Notes:
CHAPTER 9—GLOSSARY
AACSC - Air conditioning system controller
ADP - Air driven pump
APB - Auxiliary power breaker
APU - Auxiliary power unit
ARINC - Aeronautical radio incorporated
ATS - Air turbine starter
ATSCV -Air turbine starter control valve
BBAT - Battery
BAV - Bleed Air Valve
BITE - Built in test equipment
BLV - Bleed load valve
BPCU - Bus power control unit
CC - Centigrade
CFDS - Centralized fault display system
CDU - Control display unit
Glossary
DDCU - Data collection unit
DMM - Data memory module
EECS - Environmental control system
ECU - Electronic control unit
EEPROMS- Electronically erasable programmable read only memory system
EGT - Exhaust gas temperature
EICAS - Engine information crew alerting system
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131-9B Line Maintenance Training Manual
Notes:
FF - Fahrenheit
FCU - Fuel control unit
FSM - Field service monitor
GGCU - Generator control unit
HHOT - High oil temperature
IIDD - Interface data dictionary
I/O - Input/output
IOC - Input output generator
IOC LA- Input output generator left channel A
IOC RA- Input output generator right channel A
IGV - Inlet guide vane
IGVA - Inlet guide vane actuator
IOT - In operation tests
J/K/LL/C - Load compressor
LCV - Load control valve
LOP - Low oil pressure
Glossary
LRU - Line replaceable unit
LVDT - Linear variable differential transformer
MMDC - Maintenance data computer
MFD - Mulyifunction display
MES - Main engine start
MMEL - Master minimum equipment list
NNVM - Non volatile memory
Page 9-2
O/PPBA - Push button annunciator
Pcd - Compressor pressure discharge
PSI - Pounds square inch
PSIA - Pounds square inch absolute
PSID - Pounds square inch differential
PSIG - Pounds square inch gauge
PUT - Power up test
Q/RROM - Read only memory
RPM - Revolutions per minute
RTD - Resistance temperature device
RTL - Reset to load
RVDT - Rotary variable differential transformer
SSCV - Surge control valve
SOV - Shut off valve
SRU - Shop replaceable unit
STS - Status
TTM - Torque motor
Glossary
U/V/WWOW - Weight on wheels
X/Y/Z
Page 9-3