B767 ATA 29 Student Book

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    B767-3S2F ATA 29-00Page - 1 11/7/13 EFF - ALL

    HYDRAULIC POWER

    CH 29

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    ATA 29 HYDRAULIC POWER TABLE OF CONTENTS:

    HYDRAULIC POWER TABLE OF CONTENTS.....................................2

    INTRODUCTION ................................................................................... 4

    HYDRAULIC SYSYTEMS ..................................................................... 6

    SERVICING........................................................................................... 8

    GROUND POWER CONNECTIONS................................................... 10

    PRESSURE TRANSMITTER LOCATIONS......................................... 12

    FLIGHT COMPARTMENT CONTROLS & INDICATIONS .................. 14

    QUANTITY INDICATING SYSTEM..................................................... 16

    RESERVOIR TEMPERATURE INDICATING...................................... 18

    HEAT EXCHANGER ........................................................................... 20

    TYPICAL LEFT / RIGHT HYDRAULIC FLOW DIAGRAM................... 22

    LEFT / RIGHT SYSTEM COMPONENT LOCATIONS........................ 24

    ENGINE DRIVEN PUMP (EDP) LEFT & RIGHT CONTROL .............. 26

    EDP CONTROL - LEFT AND RIGHT SYSTEM .................................. 28

    EDP SUPPLY SHUTOFF VALVE - LEFT & RIGHT SYSTEMS.......... 30

    ALTERNATING CURRENT MOTOR PUMP (ACMP) ......................... 32

    L / R ACMP CONTROL - PRESSURE AND OVERHEAT IND............ 34

    CENTER SYSTEM DIAGRAM ............................................................ 36CENTER SYSTEM COMPONENTS ................................................... 38

    CENTER SYSTEM ACMP ELECTRICAL CONTROL......................... 40

    AUTOMATIC ISOLATION OF ACMP NUMBER 1 .............................. 42

    AIR DRIVEN PUMP (ADP) COMPONENTS ....................................... 44

    ADP CONTROL LOGIC....................................................................... 46

    ADP OPERATION............................................................................... 48

    RAM AIR TURBINE (RAT) .................................................................. 50

    RAT OPERATION ............................................................................... 52

    RAT CONTROL LOGIC....................................................................... 54

    POWER TRANSFORMER UNIT (PTU) STAB TRIM .......................... 56

    PTU SYSTEM...................................................................................... 58

    PTU CONTROL LOGIC....................................................................... 60

    http://67-29final%202-20-01.pdf/http://67-29final%202-20-01.pdf/http://67-29final%202-20-01.pdf/http://67-29final%202-20-01.pdf/
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    STUDENT NOTES:

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    INTRODUCTION

    Location

    The three hydraulic systems are identified by location. They are the left, center,

    and right systems.

    The left system is located in the left engine strut and contains approximately 17

    gallons of hydraulic fluid.

    The center system is located in or near the right main wheel well and contains

    approximately 40 gallons of fluid.

    The right system is located in the right engine strut and contains approximately

    20 gallons of hydraulic fluid. This equates to a total capacity of approximately

    77 gallons.

    Multiple Systems

    The three systems - left, center, and right - have no interconnection. They are

    color-coded on their tubing runs for ease of identification:

    Left = Red

    Center = Blue

    Right = Green

    Multiple Pressure Sources

    Two Engine Driven Hydraulic Pumps (EDP) are used, one on each engine.

    These are primary pumps in the left and right systems.

    Four Alternating Current Motor Pumps (ACMP) are used. Two serve as primary

    pumps in the center system, while one each serves as the demand pump in the

    left and right systems.

    An Air Driven Pump (ADP) is the demand pump in the center system. Air power

    comes from the airplane pneumatic system, which in turn may be supplied by

    engine bleed, APU or a ground source such as an air cart.

    A Ram Air Turbine (RAT) pump in the center system which serves as an

    emergency source of hydraulic pressure is powered by the slipstream.

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    INTRODUCTION

    COLOR CODE - RED

    RESERVOIR, FILTERS(IN HYDRAULIC BAY IN STRUT)

    LEFT SYSTEM

    ONE EDPONE ACMP

    RIGHT SYSTEM

    COLOR CODE - GREEN

    RESERVOIR, FILTERS

    (IN HYDRAULIC BAY IN STRUT)

    ONE EDPONE ACMP

    CENTER SYSTEM

    COLOR CODE - BLUE

    ONE RATRESERVOIR, FILTERS

    TWO ACMPONE ADP

    (IN OR NEAR RIGHT MAIN WHEEL WELL)

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    HYDRAULIC SYSTEMS

    General

    Each of the three separate hydraulic systems operates with an approximate

    pressure of 3000 PSI. Any of the acceptable BMS 3-11, type IV fluids such asSkydrol may be used.

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    HYDRAULIC SYSTEMS

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    SERVICING

    Location

    The reservoir service station is located in the right-hand aft body fairing area

    immediately aft of the RH wheel well.

    Purpose

    The reservoir service station provides convenient single point servicing for

    checking and maintaining fluid levels in all three hydraulic reservoirs.

    Components

    A four-position selector valve and switch is controlled by a single lever that

    selects the reservoir to be serviced and to be indicated on the hydraulic quantity

    gauge.

    Note: To attain a proper fluid level in the reservoirs, the reservoirs must

    be serviced with all landing gears down, gear doors closed, steering

    and flight controls neutral. When servicing right system the brake

    accumulator pressure gage must read at least 2500 psi.

    The hydraulic quantity gauge is calibrated in percent of full increments

    (110%=1.1) with a green band between .80 and 1.1 indications.

    Two sight glasses are installed on each reservoir. The lower REFILL sight glass

    gives indication to replenish reservoir. The upper OVERFILL sight glass gives

    indication to drain reservoir to FULL level.

    A pressure-fill port, service filter, and a hand pump with handle and suction hose

    are also located in the reservoir service station.

    CAUTION: DO NOT EXCEED 150 PSI FILL PRESSURE WHEN SERVICING

    HYDRAULIC RESERVOIR. EXCESSIVE PRESSURE COULD

    DAMAGE RESERVOIR.

    WARNING: CARE SHOULD BE TAKEN NOT TO OVERFILL THEHYDRAULIC RESERVOIR. OVERFILLING CAN CAUSE

    HYDRAULIC FLUID TO ENTER THE PNEUMATIC DUCTING

    AND THE AIR CONDITIONING PACKS RESULTING IN

    SMOKE AND NOXIOUS FUMES ENTERING THE FLIGHT

    DECK AND PASSENGER CABIN. REPEATED HYDRAULICCONTAMINATION OF THE PNEUMATIC SYSTEM CAN ALSO

    RESULT IN DAMAGE TO TITANIUM DUCTS.

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    SERVICING

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    GROUND POWER CONNECTIONS

    General

    Ground power connections consisting of quick disconnects for pressure and

    return lines are provided for each hydraulic system. These connections are theattachment points for an external hydraulic pressure source.

    The left and right hydraulic systems each have two sets of ground power

    connections. One set is in the engine strut hydraulic bays. The pressure

    connection is on the EDP filter module and the return connection is on the filter

    module. The second set is in the aft right wing/body fairing for the right system

    and on the keel beam between the wheel wells for the left and center systems.

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    GROUND POWER CONNECTIONS

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    PRESSURE TRANSMITTER LOCATIONS

    General

    The three hydraulic systems each have an independent system for sensing

    pressure. Separate circuit breakers provide electrical power to interchangeabletransmitters.

    Pressure signals are sent to EICAS computers. Then the computers furnish

    EICAS display with hydraulic pressure on the ELEC/HYD maintenance page

    only.

    Pressure Transmitter Locations

    The left and right hydraulic system Pressure Transmitters are located on the

    inboard side support rib, of the Inboard Aileron. Access these by lowering the

    Training Edge Flaps, they are located near the rear spar.

    The hydraulic system Pressure Transmitter for the center system is located on

    right-hand main gear wheel well keel beam. It is just above the #1 Alternating

    Current Motor Pump (ACMP) Pressure Isolation Valve.

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    PRESSURE TRANSMITTER LOCATIONS

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    FLIGHT COMPARTMENT CONTROLS & INDICATIONS

    Location/Orientation

    The control panel for hydraulic systems is located on the left side of the P5

    Overhead Panel. The upper section of the control module has system LowPressure and Reservoir low quantity amber lights. The lower section has the

    control switches for the Primary and Demand Pumps along with lights for pump

    and system conditions.

    System Indications

    The left and right SYS PRESS lights through a relay controlled circuit, will

    illuminate at 1900 PSI or less and go off at 2400 PSI or more if the Engine

    Driven Pump (EDP) is on; and will illuminate at 1300 PSI or less and go off at

    1700 PSI or more if the EDP is off. The center SYS PRESS" light illuminates at

    1300 PSI or less and goes off at 1700 PSI or more from a separate independent

    low pressure switch. The "QTY" lights illuminate if the respective reservoir fluidquantity is 48% or less of the normal full amount. All four pump "OVHT" lights

    illuminate at 230oF or more and go off at 185oF or less. The EDP overheat is

    Case Drain fluid temperature while Alternating Current Motor Pump (ACMP)

    overheat is Motor Case fluid temperature.

    Primary Pump Switch

    The Primary Pump Switches are square alternate action switch lights with an

    "ON" legend visible when the switch light is latched in and an amber pump low

    "PRESS" light.

    Demand Pump Control

    The Demand Pump Switches are rotary, three position, "OFF", "AUTO",and

    "ON" switches. In "AUTO" the pump runs on demand, for example, when the

    primary pump is unable to maintain system pressure. The pumps run

    continuously in the "ON" position. In the left and right systems "AUTO" controls

    the ACMP by a pressure switch sensing system pressure - 1900 PSI is "on" and

    2400 PSI or more is "OFF", with time delays to reduce pump cycling. In the

    center system "AUTO" controls the Air Driven Pump (ADP) by the same

    pressure settings. The ADP is also controlled by Landing Gear, Flap/Slat and

    Spoiler handle position inputs to meet the high hydraulic flow demands of these

    systems during take-off, approach and landing.

    The left and right Demand Pump "PRESS" lights illuminate at 1300 psi or less

    and go off at 1700 psi or more. The center Demand Pump "PRESS" light

    illuminates at 1900 psi or less and goes off at 2400 psi or more. The Demand

    Pump "OVHT" lights operate at the same temperatures as the primary pumps

    with the left and right ACMP sensing Motor Case fluid temperature while the

    center "ADP'' senses Case Drain fluid temperature.

    EICAS Display Units (P2)

    Hydraulic system messages are displayed on the EICAS display unit.

    Aft Control Stand (P8)

    The engine fire handles control fluid supply to the engine driven hydraulic

    pumps and pump de-pressurization solenoid.

    Side Panel (P61)

    Flight control shutoff valve switches control operation of 6 valves that can

    isolate hydraulic flow to the wing and tail systems.

    Ram Air Turbine (RAT)

    A RAT control switch is located o the P-5 Engine Start Panel, and is used for

    manual deployment. This switch also indicates both PRESS and UNLKD

    conditions for the RAT

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    FLIGHT COMPARTMENT CONTROLS & INDICATION

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    QUANTITY INDICATING SYSTEM

    Purpose

    An all solid state hydraulic quantity monitoring system provides reservoir fluid

    level information for each system.

    Components

    A capacitance probe in each reservoir senses fluid level. As fluid level changes,

    the amount of the probe immersed in fluid will vary thus affecting the probe

    capacitance. Probes in the left and right reservoirs are interchangeable. A

    larger probe is used in the center system reservoir.

    The Hydraulic Quantity Monitor is located on the E2-4 shelf in the Main

    Electronics Compartment (MEC). The Hydraulic Quantity Monitor provides

    conditioned signals to the EICAS computers for fluid level indication, the

    Remote Quantity indicator in the hydraulic servicing station in the right wingbody fairing, the "QTY" lights on the P5 overhead panel, and the automatic

    isolation of reserve brakes and steering.

    Operation

    Analog output signals from the Hydraulic Quantity Monitor are digitized by the

    EICAS computers and displayed on the EICAS status and maintenance pages

    as hydraulic quantity in terms of percent (%) of full. The decimal 1.00 indicates

    a full reservoir.

    If the reservoir is filled to 1/4 above the full level (1.22), a magenta overfillmessage "OF" will be displayed next to the quantity indication on both the status

    and maintenance pages. The "OF" message will be displayed only when the

    airplane is on the ground. When the fluid level falls to .75 and lower a magenta

    re-fill "RF" message indicating need for refill is added to the decimal display on

    EICAS (.75 RF ).

    If the fluid level falls to .48 and lower an amber "QTY" light on the P5 overhead

    panel is illuminated and an advisory "(L,C,R) HYD QTY" message is displayed

    on the upper EICAS.

    Two sight glasses on each reservoir also indicate fluid status. Absence of fluid

    at the lower sight glass indicates the need to refill. Fluid appearing in the upper

    sight glass indicates an overfill condition.

    Dispatch Deviation

    HYD QTY (EICAS or Low QTY Lights.) "INOP":

    Check applicable Hydraulic System reservoir level for proper fluid quantity

    using the fill indicator at the fill station.

    A sight gauge installed on each reservoir may be used to check the

    reservoir fluid level if the fill indicator at the fill station is inoperative.

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    QUANTITY INDICATING SYSTEM

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    RESERVOIR TEMPERATURE INDICATING

    Operation

    A variable resistance temperature transmitter is mounted on each hydraulic

    reservoir. As the hydraulic fluid temperature changes, the EICAS computer

    measures the change in resistance and indicates the temperature on the lower

    EICAS display.

    The left EICAS computer controls the temperature indication for the left and

    center reservoirs while the right EICAS computer controls the right reservoir

    temperature indication. This system is provided for maintenance

    troubleshooting and high reservoir temperatures will not result directly in other

    fault annunciation. Reservoir temperature indication is shown on the EICAS

    ELEC/HYD maintenance page in degrees centigrade.

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    RESERVOIR TEMPERATURE INDICATING

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    HEAT EXCHANGER

    Description

    Three identical heat exchangers cool case drain fluid for all hydraulic pumps

    except the RAT. For adequate heat dissipation, a minimum of 600 gallons offuel must remain in each wing fuel tank.

    Locations

    The heat exchangers are installed in the inboard ends of the left and right wing

    fuel tanks as indicated:

    Left hydraulic system, WS 288 on stringer 2, 3, 4 and 5 LH wing

    Center hydraulic system, WS 288 same stringers, RH wing

    Right hydraulic system, WS 313.5 same stringers, RH wing

    They are mounted on angle strips on top of stringers.

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    HEAT EXCHANGER

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    TYPICAL LEFT / RIGHT HYDRAULIC FLOW DIAGRAM

    Flow Path

    A reservoir pressurization module maintains a head pressure in the reservoir.

    Fluid flows to the Engine Driven Pump (EDP) is through a reservoir standpipe.

    The EDP provides 3000 psi hydraulic fluid to operate right system components.

    A fire switch operated supply shutoff valve in this supply line can be closed to

    prevent fluid from going to the engine driven pump in the event of an engine

    shutdown due to fire.

    EDP case drain fluid is used for lubrication and cooling of the pump.

    Pressure and case drain outputs are filtered in a common module. Case drain

    fluid is cooled in a fuel cooled heat exchangers.

    An Alternating Current Motor Pump (ACMP) is a demand source of system

    pressure. A separate filter module filters ACMP case drain and pressure output.

    Pump pressures and system pressure are monitored by pressure switches.

    System pressure is also monitored by a pressure transducer and transmitted to

    the EICAS computers. System fluid returning to the reservoir passes through a

    return filter.

    Loads

    Right system pressure is provided to the:

    Ailerons

    Spoilers

    Lateral Central Control Actuators (LCCA)

    Rudder

    Elevator autopilots and Power Control Actuators (PCA)

    Normal brake system

    Power transfer unit motor

    A motor-operated shutoff valve provides control of fluid flow for the Engine

    Driven Hydraulic Pumps (EDP). The hydraulic lines to the tail (empennage)

    area and the wing units have isolation valves for maintenance use. If loss of

    both hydraulic systems occurs for Stabilizer operation, a Power Transfer Unit

    (PTU) pressurizes left system return fluid and provides it to the stabilizer control

    module.

    Left Hydraulic System

    The left hydraulic system is similar to the right system. Check valves and fuses

    are installed in the left system rudder and elevator pressure and return lines toprotect the left hydraulic system in the event of a loss of a horizontal or vertical

    stabilizer.

    Loads

    The left hydraulic system supplies power for primary flight controls and some

    secondary controls.

    Ground Power Connection

    Ground hydraulic power connections are located on the EDP and return filtermodules in the aft part of the engine strut.

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    TYPICAL LEFT / RIGHT HYDRAULIC FLOW DIAGRAM

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    LEFT / RIGHT SYSTEM COMPONENT LOCATIONS

    Engine

    The Engine Driven Pump (EDP) is located on the forward, left side of the

    Accessory Gear Box.

    Aft Engine Strut

    The reservoir, EDP Supply Shut Off Valve, Alternating Current Motor Pump

    (ACMP), return filter module, EDP filter module, ACMP Filter Module, Reservoir

    Pressurization Module, and ground service connections are all located in the aft

    engine strut area.

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    LEFT / RIGHT SYSTEM COMPONENT LOCATION

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    ENGINE DRIVEN PUMP (EDP) LEFT & RIGHT CONTROL

    EDP Location

    Each EDP weighs approximately 38 pounds and is located on the engine

    gearbox.

    EDP Connections

    Pressure and case drain hoses have check valve fittings at the pump, while the

    supply hose is connected by a self sealing disconnect.

    Compensators Valve and Depressurization Solenoid

    The spring in the compensator valve operates the valve to direct flow to the

    control piston to maintain system pressure at approximately 3000 psi during

    normal operation (no flow).

    The EDP has a maximum flow rating of 37 gpm at 3700 rpm at 2850 psi. Pump

    output is approximately 24 gpm at idle engine speed.

    The pump is depressurized (no flow condition) by powering a solenoid operated

    valve. This directs pressure to the compensator valve to reduce yoke angle and

    to the blocking valve to cut off the hydraulic output. The solenoid may be

    powered by the pump control switch (P-5) in the OFF position or by using the

    fire handle

    Secondary Pressure Sources (System Demand)

    The left and right hydraulic systems each have an Alternating Current Motor

    Pump (ACMP) as a demand source of pressure. These (pump) sources are

    triggered "ON" when the primary pumps cannot maintain sufficient pressure. In

    the left and right systems, each ACMP rated at 7 gpm. These are identical to

    and interchangeable with the ACMP'S used in the center system as primary

    pumps.

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    ENGINE DRIVEN PUMP (EDP) LEFT & RIGHT CONTROL

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    EDP CONTROL - LEFT AND RIGHT SYSTEM

    EDP Push Switch

    The control switch for the EDP is a square shaped alternate action push-button

    switch on the P5 overhead panel. Both the white "ON" mechanical flag and theamber "LOW PRESS" light are located on the face of the switch.

    Function

    As the pump is switched to the "OFF" condition, the white "ON" is hidden by a

    mechanical shutter and the pump depressurization solenoid valve is energized

    to close and prevent further fluid flow to the system. The pump will continue to

    run as long as the engine rotates. There is no time limit to pump operation while

    depressurized as long as a supply flow to the pump is available.

    The pressure light is always active and will illuminate when the pump is de-

    pressurized or pressure at the pump outlet is low (at or below 1900 psi).An EICAS advisory message will identify the pump (i.e., L HYD PRIM PUMP).

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    EDP CONTROL - LEFT & RIGHT SYSTEM

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    EDP SUPPLY SHUTOFF VALVE - LEFT & RIGHT SYSTEMS

    General

    An Engine Driven Pump (EDP) supply shutoff valve is located at the forward

    end of each engine strut bay. It is mounted on the engine strut aft bulkhead.

    Access is through the engine strut left access panel.

    Operation

    The two position valves are electrically operated and are normally open. Valve

    position is controlled through the associated engine fire switch and is controlled

    with 28vdc power from the battery bus. When the valve is selected closed, the

    EDP depressurization solenoid is also energized. A red valve position indicator

    extends from the side of the valve/motor drive housing to show valve position.

    The valve cannot be manually operated.

    CAUTION: PUMP OPERATION OF MORE THAN 5 MINUTES WITH THEVALVE CLOSED AND ENGINE TURNING MAY DAMAGE THE

    PUMP. SEE THE MAINTENANCE MANUAL FOR INSPECTION

    PROCEDURE.

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    EDP SUPPLY SHUTOFF VALVE LEFT & RIGHT

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    ALTERNATING CURRENT MOTOR PUMP (ACMP)

    Primary Pressure Source

    The center system has two Alternating Current Motor pumps (ACMP) rated at 7

    gpm each as its primary hydraulic source.

    General Description

    ACMPS act as demand pumps in the left and right hydraulic systems to

    augment the Engine Driven Pump (EDP) and provide hydraulic power for

    ground systems tests when the engines are not operating. Two ACMPs are the

    primary pumps in the center hydraulic system. The 4 pumps are identical and

    interchangeable.

    Two types of pumps are available, Abex or Vickers. The pumps are similar in

    output and operation. Both are variable displacement, pressure compensated,

    constant horsepower hydraulic pumps. The electric motors are 115 volt threephase, continuous duty, explosion proof units. They are fluid cooled and each

    has a thermal switch that closes at 225F for overheat indication. The AC

    motors draw approximately 45 amps at maximum power and approximately 167

    amps peak starting current per phase. The ABEX ACMP has an external ripple

    damper to smooth the pump output. It is rated at 6 GPM at 2850 PSI at 5700

    RPM. Below 2850 PSI the pump is compensated so that pump delivery will

    increase to 12 GPM at 1200 PSI.

    The Vickers ACMP has an internal ripple damper. It is rated at 7 GPM at 2850

    PSI at 5700 RPM. Below 2850 PSI, the pump is compensated so that pump

    delivery increases to 14 GPM at 1500 PSI.

    Maintenance Practices

    Continuous pump operation is possible when the system heat exchanger is in a

    fuel tank containing a least 4020 lbs of fuel (600 gal., 1827 kg). If the fuel tank

    contains less than 4020 lbs limit operation to 10 minutes followed by a minimum

    of 20 minutes cooling. Stop pump operation if hydraulic reservoir fluid

    temperature exceeds 100C or the pump overheat light/message illuminate.

    Secondary Pressure Sources (System Demand)

    The center system Air Driven (ADP) pump, is rated the same as primary

    (EDP's) in left and right systems, but are not interchangeable. . Also in the

    center system has a Ram Air Turbine pump (RAT) rated at 11.3 gpm, used to

    power flight controls in emergencies only.

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    ALTERNATING CURRENT MOTOR PUMP (ACMP)

    B767 3S2F ATA 29 00

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    L / R ACMP CONTROL - PRESSURE AND OVERHEATINDICATION

    Alternating Current Motor Pump (ACMP) OFF or ON

    The ACMP low pressure light (L9) is connected to the ACMP low pressureswitch (S30). It is illuminated when the pump switch (S7) is in the OFF

    position and when the pressure is below 1300 PSI with the switch ON. The

    system low pressure light is connected to on the Engine Driven Pump (EDP)

    filter module.

    ACMP Auto Mode

    When Engine Driven Pump (EDP) pressure drops to 1900 psi for longer than

    0.3 second, the EDP low pressure switch turns on the ACMP. The on control

    relay latches on a ground through relay (K126). This relay closes a circuit thru

    (K128) ACMP Off Control relay, energizing the power relay in the ACMP

    Electrical Control Unit (ELCU M896) turning on the ACMP.

    The EDP low pressure sense relay (K127) switches the system low pressure

    light (L3) from pump control pressure switch (S32) to the ACMP low pressure

    switch (S30). The EDP low pressure light (S4) always responds to the EDP

    pressure switch (S31) regardless of the position of the ACMP control switch

    (S4).

    If pressure at the ACMP low pressure switch (S30) drops below 1300 psi, both

    the ACMP low pressure light (L9) and system low pressure light (L3) illuminate.

    The ACMP low pressure light (L9) is connected to the pump control pressure

    switch (S30) when the ACMP is not running. When the ACMP turns on, the

    ACMP On control relay (K126) switches the ACMP low pressure light (L9) to the

    ACMP low pressure switch (S30).

    When the EDP pressure is restored above 2400 PSI the EDP pressure sense

    relay (K127) is de-energized enabling the ACMP OFF control relay (K128) to

    energize after a 15-second time delay. As the ACMP OFF control relay (K128)

    energizes, it interrupts the holding circuit to the ACMP ON control relay (K126)

    turning off the ACMP.

    ACMP Anti-cycle Protection

    The anti-cycle protection circuit in the ACMP ELCU is energized whenever the

    ACMP demand pump switch (S7) is in either the AUTO or ON position. The

    anti-cycle protection circuit prevents the ACMP from restarting automatically

    after an ELCU auto shutdown for an electrical fault. To restart the ACMP afteran ELCU auto shutdown the anti-cycle protection circuit must first be reset by

    turning the demand pump switch (S7) to the OFF position.

    Engine Start

    Left ACMP operation is inhibited on the ground during the engine start cycle on

    either engine.

    Overheat Indication

    ACMP overheat indication is controlled by a temperature sensing switch on thepump which monitors hydraulic fluid temperature in the pump housing. The

    switch will close at 225 degrees F causing the ACMP overheat light to illuminate

    and the EICAS advisory message "L DEMAND HYD OVHT" to appear.

    Takeoff Operation Right System Only

    When in the ground mode the right ACMP will run continuously whenever the

    slats are commanded to takeoff either by the flap handle or the alternate

    position select and slat arming switches, as sensed by the flap/slat electronics

    unit (FSEU). This is to ensure uninterrupted braking power in the event of a

    RTO due to right engine failure.

    Note: Right system shown in graphic, left system similar.

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    L/R ACMP CONTROL - PRESSURE AND OVERHEAT INDICATION

    B767 3S2F ATA 29 00

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    CENTER SYSTEM DIAGRAM

    Reservoir

    This reservoir is similar to those in the left and right systems, but it holds more

    fluid. The center reservoir is a 14.7 gallon container holding 8.6 gal. When full,

    actual volume may be obtained as status on EICAS; otherwise, low quantity will

    be indicated by an amber "RSVR/QTY" light. The temperature of hydraulic fluid

    in the reservoir is available on the EICAS ELEC/HYD maintenance page.

    Alternating Current Motor Pump (ACMP)

    The Primary Pumps in the center system are Alternating Current Motor Pumps

    (ACMP) units with Alternate Action switch lights for control on the P5 panel.

    Each switch light has an amber low pressure "PRESS" light operating from a

    switch in the respective ACMP filter module at or below 1300 psi. Overheat

    "OVHT" amber lights for each ACMP illuminate at 230oF in each motor case.

    Air Driven Pump (ADP)

    The Demand Pump in the center system is air driven by a turbine and controlled

    by a rotary switch with "OFF", "AUTO" & "ON" positions the same as the left and

    right ACMP'S. The "AUTO" mode is controlled through this select switch and

    S29 pressure switch in the filter module, or an anticipatory circuit involving Gear,

    Flaps, Slats and Speedbrake handle. Protection from turbine over-speed is

    provided by a trip mechanism. Overheating (230oF) of the fluid is detected in

    the case drain fluid in the filter module.

    Ram Air Turbine (RAT)

    The RAT is automatically deployed by low engine n2rpm (50% or less) on both

    engines while in flight with airspeed greater than 80 knots. Manual deployment

    may be performed by an Alternate Action type switch on the P5 overhead panel.

    A separate pressure switch (1700 psi) in the RAT mode in the right wheel well

    turns on the green "Press" light in the switch light on the P5 panel for RAT

    pressures of 1700 psi or greater. The RAT may be retracted, after proper blade

    orientation, on the ground only.

    A check valve in the hydraulic line from center system primary and demand

    pumps makes it possible for the RAT developed pressure to only power primary

    flight controls, Stabilizer and Spoilers. A separate relief valve permits RAT over-

    pressure flow to the reservoir.

    Isolation Valves

    Two isolation valves may be used to direct below standpipe hydraulic fluid

    through C1 to the reserve brake and steering system. These valves (reservoirisolation and pressure isolation) are controlled by the reserve brake and

    steering switch on the P1-3 panel. This switch will also turn on the C1 Hydraulic

    Pump. Isolation valve failures are indicated by the RSV BRAKE VAL EICAS

    message.

    System Pressure

    The center system pressure transmitter is located upstream of the #1 ACMP

    Isolation Valve so that the full range of system pressure may be available for

    crew maintenance surveillance on EICAS even through #1 ACMP has been

    isolated for reserve brakes and steering. The system pressure light switch is

    downstream of the pressure line isolation valve and will illuminate as the valve

    closes unless the ADP or #2 ACMP are on.

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    CENTER SYSTEM DIAGRAM

    TRAINING MANUALB767 3S2F ATA 29 00

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    CENTER SYSTEM COMPONENTS

    Right-Hand Wheel Well Keel Beam

    Two Alternating Current Motor Pumps (ACMP), Reservoir And Reservoir

    Pressurization Module, two ACMP Isolation Valves, two ACMP Filter Modules, a

    system Pressure Transducer, a System Low Pressure Switch, system Return

    Filter and RAT Control/Checkout Module are located in right main wheel well.

    Right-Hand Wing To Body Fairing Area

    The Ram Air Turbine (RAT) and hydraulic reservoir service panel are located in

    compartments aft of right-hand main wheel well. The reservoir air

    pressurization service/check-out module for all three hydraulic systems is also

    located aft of the right wheel well.

    Left-Hand Wing To Body Fairing

    The Air Driven Pump (ADP) is located in the compartment just aft of the left

    main wheel well.

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    CENTER SYSTEM COMPONENTS

    TRAINING MANUALB767-3S2F ATA 29-00

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    CENTER SYSTEM ACMP ELECTRICAL CONTROL

    Power Sources

    The #1 Alternating Current Motor Pump (ACMP) is always operable with power

    on the left AC/DC buses. ACMP #1 can also be turned on by the Reserve

    Brakes and Steering Switch if the pump control switch (S2) is off.

    The #2 ACMP is only operable when the right AC/DC buses are powered and

    there are two generators supplying power, in which case either one or both Bus

    Tie Breakers (BTB'S) will be open.

    When there is only one source of power, either in flight or on the ground, both

    BTB's will be closed. When both BTB's are closed, the #2 ACMP can be

    operated only through secondary contacts in the Electrical Control Units (ELCU)

    of the other three ACMP'S when the associated ACMP is off.

    The control circuit through the left hydraulic system ELCU is disabled duringengine start. This prevents #2 ACMP from coming on line when the left ACMP

    drops off during an engine start with only one generator power source available.

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    CENTER SYSTEM ACMP ELECTRICAL CONTROL

    TRAINING MANUALB767-3S2F ATA 29-00

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    AUTOMATIC ISOLATION OF ALTERNATING CURRENTMOTOR PUMP (ACMP) NUMBER 1

    Purpose

    Isolation Valves controlled by the Reserve Brakes and Steering Switch provides

    a means of pressurizing alternate brakes and nose wheel steering using the #1

    ACMP and fluid isolated below the standpipe level from the center reservoir. If

    center system fluid is lost, isolation of fluid occurs automatically at the low

    quantity warning level. If both center and right hydraulic systems are lost this

    system allows for regaining brakes and nose wheel steering. If only the center

    system is lost, steering may be regained while brakes remain on the right

    hydraulic system.

    Components

    Pressure Isolation Valve, Number 1, is a motor driven valve that shuts off

    hydraulic pressure to all center systems except nose wheel steering and thealternate brake system.

    Supply Isolation Valve, Number 2, is a motor driven valve that switches the #1

    ACMP hydraulic supply from the reservoir standpipe to the bottom of the

    reservoir to access the reserve fluid supply below the standpipe.

    Reserve Brakes and Steering switch is a lighted push-button switch containing a

    white "ON" legend and an amber "VALVE" light located on the P1-3 panel.

    Reset/Disable switch is a toggle switch on the P-61 panel to reset the automatic

    isolation system or to disable the auto function while performing ground

    maintenance.

    Operation

    Actuation of the reserve brakes and steering switch turns on the #1 ACMP, if off,

    and shows the "ON" legend in the switch.

    Electric power is first supplied to drive the Supply Isolation Valve to the closed

    position. When fully closed, the Supply Isolation valve directs power to drive thePressure Isolation Valve to the alternate position. An amber "VALVE" light in

    the lower half of the reserve brakes and steering switch will illuminate to indicate

    a disagreement between the switch position and the position of either valve. If

    the disagreement exists for 6 seconds an EICAS advisory message "RSV

    BRAKE VAL" will be annunciated.

    With the reserve brakes and steering switch in the unlatched position, both the

    Pressure and Supply Isolation Valves will operate to the closed and alternate

    positions respectively when center system fluid reaches "LOW" quantity level

    (48%) and the airplane is in flight. The pump (#1 ACMP) then must be activated

    by pressing the reserve brakes and steering switch or the #1 ACMP switch. A

    white "ISOLATION" light on the P-61 right side panel will illuminate when either

    isolation valve is not in the open (normal) position.

    While the Reserve Brakes and Steering switch is selected "ON", center system

    pressure will still be transmitted to the EICAS computer. However the system

    low pressure switch (S-35) is isolated from pressure causing the center system

    low pressure light to illuminate and the EICAS C level message (Low

    Pressure) to appear.

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    S1 RES BRK &STRG RESET

    SW

    NORMAL

    DI SABLE

    RESET/

    S2 ACMP C1

    SEL SWI TCH (P1- 3)

    SEL SW( P5)

    K124 ( P36)

    SOURCE SELECT MAI NT PNL ( P61)

    TO EI CAS

    SENSE RLY

    K2

    K4 PWR K5 TD RELAY

    TD

    SEC

    10

    SUPPLY

    POWER

    BUSGND SVC115V AC

    L20

    HYD QTY

    P11 CB PANEL

    P11 CB PANEL

    L/ R EI CAS COMPUTERS

    VAL" BRAKE"RSV

    6 SEC

    2

    13

    C SYS

    I SOLATI ON VALVE

    RES BRKS & STRG

    L15

    SET

    RESET

    L- 1

    VLV RLY

    . 3 SEC TD

    TD

    QTY MON

    M1216 RESERVE BRAKES & STRG HYD

    HYD SYS C NO. 2

    K1 I SLN

    LOWK3

    RLY

    LATCH

    QTY

    P5

    1

    "C HYD QTY"

    1

    1

    MD & T POWER1

    1

    AI R

    GND

    M122 HYD

    wI SOLATED

    PRESS SW

    S33 ACMP C- 1

    PTO PUMP

    PRESS

    ON

    QTY

    AUTO

    a

    VALVE

    ON

    a

    L BUS28V DC

    ' C' SYSLOW

    ( E2-4)V110 NO. 1 I SOLATI ON

    V111 NO. 2 I SOLATI ON

    VALVE, PRESS.

    VALVE, SUPPLY

    RI GHT WHEEL WELL KEEL BEAM

    M342 HYD SYS C

    NC

    D474

    NO. 2 I SOLATI ON

    ACMP NO. 1

    N0. 1

    RESERVOI R

    NO. 2)( ADP/ ACMP

    TO SYS

    I SOLATI ON VALVEHYD SYS C NO. 2

    PUMP C1 PRESS

    LEGEND

    VALVE

    RETURN

    EXCHANGERTO HEAT

    AIR

    RETURN

    PRESSURE

    SUPPLY

    CLOSED

    NOT

    OPEN

    NOT

    NOT OPEN

    OPEN

    M

    OPEN

    NC

    CLOSE

    LI GHTPRESS.TO SYS

    PRESS. XMTR

    C PRESS.S35 HYD SYS

    NCP

    NC

    CLOSED

    CLOSED

    NOT

    OPEN

    NOT

    OPEN

    NOT OPEN

    OPEN

    M

    OPEN

    NC

    CLOSE

    S33 ELEC HYD

    TO RETURN

    NC

    1700 PSI

    P

    STEERI NG

    NOSE GEAR

    VALVEI SOL

    GEAR ACTUATI ON

    NOSE LANDI NGBRAKES

    CLOSED

    FWD

    EI CAS PRESSURE

    I NDI CATI ON

    ON

    AUTOMATIC ISOLATION OF ALTERNATING CURRENT MOTOR PUMP (ACMP) NUMBER 1

    1

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    AIR DRIVEN PUMP (ADP) COMPONENTS

    General

    The pump is a single unit with a pressure regulator/shutoff valve and modulating

    valve to control air which turns a turbine driven hydraulic pump. A muffler is

    installed in the inlet air duct to the turbine to reduce the noise level, and an

    exhaust duct directs the "spent" turbine air overboard.

    Hydraulic Pump

    The hydraulic pump produces 37 gpm at 2850 psi while turning at 5683 rpm.

    The Variable Displacement, Constant Pressure pump regulates turbine speed

    by load and has a compensated cutoff with (0) zero flow at 3025 psi. At low

    flow, turbine speed is decreased; with 2300 rpm at no load and 5683 at rated

    load. The ADP pump is driven through a 5.158:1 gear reduction gearbox

    lubricated with mil 7808 engine oil.

    The case drain fluid cools the gearbox oil through a heat exchanger in the fuel

    tank in the right wing.

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    AIR DRIVEN PUMP (ADP) COMPONENTS

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    ADP CONTROL LOGIC

    Purpose

    The demand logic circuit controls operation of the pump under different

    conditions.

    ADP Switch "OFF" - no ADP operation

    Pump Switch "AUTO" - the ADP runs dependent on the conditions listed

    below

    Pump Switch "ON" - ADP continuous run solenoid is energized and the

    pump runs continuously

    Operation (Auto Mode)

    Various conditions control the ADP operation with the switch in "AUTO"; they

    are low center hydraulic system pressure, both Alternating Current Motor Pump

    (ACMP) switch positions "OFF", gear disagree, slat disagree, flap disagree, andspeed brake handle armed while on the ground.

    Low Pressure Operation

    Low center hydraulic system pressure (1900 PSI) sensed by S29 causes the

    ADP to run for a minimum of 15 seconds. This condition is controlled by relays

    K153 & K684. ADP operation is continued for 15 seconds to ensure system

    pressure is maintained above 2400 PSI.

    Other Auto Operation

    ADP operation in "AUTO" is continuous if:

    Both center ACMP switches are "OFF"

    Slats disagree with flap lever position sensed by the PSEU

    Flaps disagree with flap lever position sensed by the FSEU Landing gear and landing gear lever positions disagree sensed by the

    PSEU

    Speed brake lever "ARMED" with the airplane in ground mode

    Hydraulic Generator Commanded ON

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    ADP CONTROL LOGIC

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    ADP OPERATION

    Operation

    The ADP is turned on by either continuous run or demand run solenoid valves.

    Control air is supplied from the regulator/shutoff valve at 13 psi through a jet

    pipe which is positioned by the hydraulic pump Swash Plate and ModulatingValve output pressure.

    The hydraulic pump swash plate angle is controlled by the pump output

    pressure. Movement of the swash plate to increase flow deflects jet pipe to

    "fast" side and opens the modulating valve to increase air flow to the turbine. A

    large swash plate angle due to low pressure, or high flow demand, increases

    valve opening to increase pump output. Pump output is 37.0 GPM at 2850 PSI

    at 5683 RPM. A small swash plate angle from high pressure or low flow

    demand, reduces valve opening to decrease pump output. Pump output is near

    0 GPM at 3025 PSI at 2300 RPM.

    Over-Speed Control

    An electronic topping circuit prevents over-speed from a sudden drop in

    hydraulic pressure. A Monopole Sensor sends a turbine speed signal to the

    Over-Speed Control Card (M1057) in the P-50 card file. Maximum speed is

    limited to 6000 - 6600 RPM. An over-speed condition causes rapid interruption

    (pulse modulating) of the signal to the controlling solenoid.

    A centrifugal over-speed switch provides over-speed shutdown by closing the

    regulator/shutoff valve if turbine speed reaches a maximum of 7100 - 7700

    RPM. An over-speed shutdown is magnetically latched and the ADP cannot be

    restarted until the solenoid valve is manually reset by a test/reset switch on thedoor of the P36 panel in the equipment center. This switch can also be used to

    test the over-speed shutdown solenoid circuit.

    ADP Over-Speed Annunciators

    The ADP Over-Speed Control Card (M1057), located in the P-50 card file

    contains three LED'S that annunciate ADP conditions labeled DS 1 - on O/S,

    DS 2 - AUTO O/S and DS3 - pwr in. Lights DS 1 and DS 2 will illuminate

    whenever over-speed topping occurs in the relevant mode and is out when

    speed is reduced back to normal range. The lights will not be on if thecentrifugal switch has caused a shutdown to occur. "DS3" is on any time the

    ADP is operating.

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    ADP OPERATION

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    RAM AIR TURBINE (RAT)

    General

    The RAT is an air turbine driven hydraulic pump that provides emergency

    hydraulic power for the flight controls in the event that power is lost on both

    engines. The RAT is stowed inside the right aft body fairing.

    Operation

    When deploying, the RAT pivots downward to extend the turbine into the

    airstream. An electric motor drives the unit for both deployment and stowing.

    The Motor extends and retracts the RAT by rotation of a motor arm and

    actuation link. A 15 Degree Limit Switch, permits partial retraction of the RAT so

    that the blade can be locked and the blade centered switch can be closed.

    Down and Up Limit Switches provide extend/retract motor shutoff at full down or

    full up travel limits. A Manual Override Switch, located on P5 panel, permits

    manual selection of RAT extension either in air or on ground.

    Hydraulic Pump

    The Abex variable displacement, compensated pump has a rated output flow of

    11.3 gpm at 2140 psi at 4165 rpm. Turbine/hydraulic pump speed ratio is 1:1.

    Turbine Blades

    Two variable pitch blades are controlled by a counterweight and governor spring

    inside the turbine hub. Governed speed is 4165 +/-45 rpm at a minimum

    airspeed of 125 knots. A lock plunger prevents blade rotation when the RAT is

    in the stowed position, and prevents complete RAT retraction unless the turbineblade is locked in the proper position for stowing. Blade lock and switch

    activation occurs when the RAT has been retracted 13.5 degrees from the

    fully-extended position.

    A Teleflex Cable unlocks the turbine blade and opens the blade lock and

    centered switch when RAT is extended.

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    RAM AIR TURBINE (RAT)

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    RAT OPERATION

    Extension

    Automatic deployment of the RAT is triggered in the air mode only by having low

    N2speed (less than 50%) on both engines and an airspeed greater than 80

    knots.

    Manual electric control of extension of the RAT may be performed by a RAT

    Guarded Override Select switch on the P5 overhead panel at any time, in flight

    or on the ground.

    Retraction

    The retraction of the RAT is possible only on the ground and is triggered by a

    guarded switch near the checkout module on the keel beam in the right main

    gear wheel well. The RAT cannot be retracted beyond 15 degrees until the

    propeller blade is centered with the locking pin in place so that the blade lockand centered switch can complete the retract circuit.

    Ground Checkout

    To accomplish the ground checkout of the RAT, the center system must have

    hydraulic pressure flow capability of 17 gpm or better. The two center ACMP'S

    both on will not provide enough flow. The ADP or a ground source of hydraulic

    power must be used.

    By pulling the handle on the checkout module in the right main gear wheel well,

    the RAT is back-driven hydraul ically. A Tachometer Module has lights to

    indicate the speed range for governor/RAT check.

    Green indicates on speed

    Red indicates over-speed

    No light Indicates under-speed

    A lamp test switch is also provided, however the RAT must be rotating in order

    to test the lamps.

    WARNING: CARE SHOULD BE TAKEN WHILE OPERATING THE RATAS THE BLADES TURN AT A HIGH RATE OF SPEED. BE

    SURE TO FOLLOW ALL PRECAUTIONS IN THE

    MAINTENANCE MANUAL.

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    RAT OPERATION

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    RAT CONTROL LOGIC

    Automatic Deployment

    Automatic extension / deployment of the RAT is possible in the AIR mode when

    both engines are shut down.

    The electrical drive of the RAT to the deployed position will stop as the motor -

    driven drive arm hits a down limit switch (S365). Any time the RAT is not full up

    (as limited by the up limit switch S369), The amber unlocked light will illuminate

    in the M49 module on the P5 panel.

    The RAT green pressure light will illuminate when its developed pressure is

    1700 psi or above.

    Manual Control

    Manual electric control of the RAT is with the guarded switch (S7) on (M49)module on the P5 panel. It is possible to do this at any time while on the ground

    or in flight. For this sequence, a separate Override Limit (down) switch (S501)

    is used - operating from the motor driven arm.

    The unlock and pressure lights are always active.

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    POWER TRANSFORMER UNIT (PTU) STAB TRIM

    General

    The power transfer unit (PTU) is a backup system to provide hydraulic power for

    the stabilizer. If the left and center hydraulic systems are not operational to

    drive the stabilizer ball-screw hydraulic motors, the PTU enables the righthydraulic system to provide a third power source for stabilizer trim.

    The PTU components are located in the stabilizer compartment on bulkheads

    above the stabilizer trim ball-screw mechanism. The PTU system is connected

    to the left and right hydraulic systems and the left stabilizer trim control module.

    The system contains the following hydraulic components:

    Right hydraulic system shutoff valve module

    Motor/pump assembly

    Pressure filter module Case drain filter module - Left hydraulic system isolation valve module

    Relief valve

    Check valves

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    PTU SYSTEM

    Power Transfer Unit

    The power transfer unit is commanded ON automatically to provide hydraulic

    power to drive the stabilizer in the event both left and center hydraulic systems

    fail.

    The following components in the power transfer unit (PTU) system provide

    hydraulic pressure to the left stabilizer trim module from an isolated left

    hydraulic system supply source. Pressure is supplied by the right hydraulic

    system pumps.

    Left System Isolation Valve

    The isolation valve is installed in the left system pressure line to the stabilizer

    trim module. The valve has two positions and is operated by a DC motor.

    When the valve is in the OFF (closed) position, it helps to isolate the part of the

    left hydraulic system which contains the PTU pump and the stabilizer trim

    module. When the valve is in the ON (open) position, it permits the usual flow of

    left system pressure to the stabilizer trim module.

    Right Hydraulic System Shutoff Valve

    The shutoff valve is installed in the right system pressure line to the PTU motor.

    The valve has two positions and is operated by a DC motor. When the valve is

    in the ON (open) position, it supplies right hydraulic pressure to operate the

    PTU motor. When the valve is in the OFF position, it removes right system

    pressure to the PTU motor. The shutoff valve also has a position indicator and

    manual override lever.

    Filter Modules

    Filter modules are installed in the pump pressure and case drain lines. The

    filters are non by-passable. The pressure filter cannot be cleaned. The case

    drain filter can be cleaned.

    Relief Valve

    A relief valve, installed between the left elevator feel computer and the left

    Stabilizer Trim Control Module (STCM), prevents loss of isolated left system

    hydraulic fluid through the elevator feel port of the left STCM. The relief valve is

    closed when pressure at the STCM feel computer port is less than 100 psi.

    PTU Return Compensator Module

    The return compensator module is installed in the left system return line from the

    stabilizer trim module. The return compensator module includes a bypass valve

    and a compensator that contains about four cubic inches of fluid. When the left

    hydraulic system is operating correctly, fluid that flows from the stabilizer trim

    module through the left system return line to the reservoir must flow through the

    return compensator. Flow through the compensator is initially blocked by the

    bypass valve. This causes fluid to be pushed into the compensator. When the

    compensator is full, the fluid pressure in the line increases until it opens the

    bypass valve to permit flow of fluid through the compensator to the left return

    system. When a failure in the left hydraulic system causes the PTU system tooperate, the left system isolation valve closes. This removes left system

    pressure from the stabilizer trim module. When the pressure in the stabilizer

    trim module return line decreases to 45 to 50 psi, the bypass valve in the

    compensator closes to isolate the PTU system from the left return system. The

    fluid in the compensator is pushed out by the piston and spring and becomes a

    source of fluid for the PTU pump inlet.

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    PTU SYSTEM

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    PTU CONTROL LOGIC

    System Control

    Operation of the PTU is controlled automatically.

    Power

    Electrical power from the left 28 vdc bus is used to operate the PTU control

    relays, the right hydraulic system shutoff valve and the left hydraulic system

    isolation valve.

    Left Hydraulic System Isolation Valve

    When the airplane is in the air, air/ground system No. 2 connects the left

    hydraulic system isolation valve controls to the left hydraulic system pressure

    and quantity indication of the left reservoir.

    The left hydraulic system isolation valve closes under either of the following

    conditions:

    The hydraulic quantity monitored in the left reservoir falls below 0.48

    The left hydraulic pressure produced by both the Engine Driven Pump

    (EDP) and the Alternating Current Motor Pump (ACMP) is low.

    If one of these conditions is removed, the left hydraulic system isolation valve

    remains closed for an additional time of 20 seconds to prevent nuisance signals

    of short duration from operating the isolation valve intermittently.

    Right Hydraulic System Shutoff Valve

    When the left hydraulic system isolation valve is commanded closed, the right

    hydraulic system shutoff valve is controlled by the control wheel stabilizer trim

    control switches and the center hydraulic system pressure.

    Loss of center hydraulic system pressure and a stabilizer electric trim commandfrom either the captain's or the first officer's control wheel switches, cause the

    right hydraulic system shutoff valve to open and start PTU operation.

    The right hydraulic system shutoff valve remains open as long as a stabilizer

    electric trim signal is present and the center hydraulic pressure is low. When

    the stabilizer electric trim signal is removed, or the center hydraulic pressure is

    restored, the right hydraulic system shutoff valve is commanded to close.

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    PTU CONTROL LOGIC