Aviation Maintenance Technician Handbook – AirframeVolume 22012

FAA-H-8083-31

Aviation Supplies & Academics, Inc.7005 132nd Place SENewcastle, Washington 98059-3153www.asa2fly.com

© 2012 Aviation Supplies & Academics, Inc.This electronic publication is comprised of the same content as the Federal Aviation Administration’s official release of this same title. ASA does not claim copyright on any material published herein that was taken from United States government sources. Bookmarks and hyperlinks have been incorporated throughout to facilitate ease of use for this electronic version. All rights reserved. No part of this electronic file may be reproduced, transmitted, shared, distributed or resold without written permission from the publisher.

ASA-8083-31V2-PD978-1-56027-953-2

iii

Volume 1Preface.....................................................................v

Acknowledgments ................................................vii

Table of Contents ................................................xiii

Chapter 1Aircraft Structures ...............................................1-1

Chapter 2Aerodynamics, Aircraft Assembly, and Rigging .................................................................2-1

Chapter 3Aircraft Fabric Covering .....................................3-1

Chapter 4Aircraft Metal Structural Repair .........................4-1

Chapter 5Aircraft Welding ...................................................5-1

Chapter 6Aircraft Wood ......................................................6-1

Chapter 7Advanced Composite Materials .........................7-1

Chapter 8Aircraft Painting and Finishing ..........................8-1

Chapter 9Aircraft Electrical System ...................................9-1

Glossary ..............................................................G-1

Index ......................................................................I-1

Volume 2Chapter 10Aircraft Instrument ...........................................10-1

Chapter 11Communication and Navigation.......................11-1

Chapter 12Hydraulic and Pneumatic .................................12-1

Chapter 13Aircraft Landing ................................................13-1

Chapter 14Aircraft Fuel System..........................................14-1

Chapter 15Ice and Rain Protection.....................................15-1

Chapter 16Cabin Environmental ........................................16-1

Chapter 17Fire Protection Systems ...................................17-1

Glossary ..............................................................G-1

Index ......................................................................I-1

Volume Contents

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Volume Contents ...................................................iii

Preface.....................................................................v

Acknowledgments ................................................vii

Table of Contents ................................................xiii

Chapter 10Aircraft Instrument Systems ............................10-1Introduction ..................................................................10-1Classifying Instruments ...............................................10-3

Flight Instruments ....................................................10-3Engine Instruments ...................................................10-3Navigation Instruments ............................................10-4

Pressure Measuring Instruments ..................................10-5Types of Pressure .....................................................10-7Pressure Instruments.................................................10-8

Engine Oil Pressure ..............................................10-8Manifold Pressure .................................................10-9Engine Pressure Ratio (EPR) ................................10-9Fuel Pressure .......................................................10-10Hydraulic Pressure ..............................................10-10Vacuum Pressure ................................................10-11Pressure Switches ...............................................10-11

Pitot-Static Systems ...............................................10-12Pitot Tubes and Static Vents ...............................10-12Air Data Computers (ADC) and Digital Air Data Computers (DADC) ...................................10-14

Pitot-Static Pressure-Sensing Flight Instruments ...10-16Altimeters and Altitude .......................................10-16Vertical Speed Indicator .....................................10-22Airspeed Indicators .............................................10-24

Remote Sensing and Indication .................................10-26Synchro-Type Remote-Indicating Instruments .....10-26

DC Selsyn Systems .............................................10-26AC Synchro Systems ..........................................10-28Remote Indicating Fuel and Oil Pressure Gauges ................................................................10-28

Mechanical Movement Indicators ..............................10-29Tachometers ...........................................................10-29

Mechanical Tachometers ....................................10-29Electric Tachometers ..........................................10-30

Synchroscope..........................................................10-32Accelerometers .......................................................10-32Stall Warning and Angle of Attack (AOA)Indicators ................................................................10-34

Temperature Measuring Instruments .........................10-35Non-Electric Temperature Indicators .....................10-36Electrical Temperature Measuring Indication ........10-36

Electrical Resistance Thermometer ....................10-36Ratiometer Electrical Resistance Thermometers .....................................................10-38

Thermocouple Temperature Indicators ..................10-38Turbine Gas Temperature Indicating Systems ...10-39

Total Air Temperature Measurement .....................10-42Direction Indicating Instruments ...............................10-43

Magnetic Compass .................................................10-43Vertical Magnetic Compass ...................................10-45Remote Indicating Compass ...................................10-45Remote Indicating Slaved Gyro Compass (Flux Gate Compass) .......................................................10-45Solid State Magnetometers .....................................10-46

Sources of Power for Gyroscopic Instruments ..........10-46Vacuum Systems ....................................................10-48

Venturi Tube Systems .........................................10-48Engine-Driven Vacuum Pump ............................10-48Typical Pump-Driven System .............................10-49Twin-Engine Aircraft Vacuum System Operation ............................................................10-50

Pressure-Driven Gyroscopic Instrument Systems ..10-51Electrically-Driven Gyroscopic Instrument Systems ...................................................................10-51

Principles of Gyroscopic Instruments ........................10-52Mechanical Gyros...................................................10-52Solid State Gyros and Related Systems .................10-54

Ring Laser Gyros (RLG) ....................................10-54

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Microelectromechanical Based Attitude and Directional Systems ............................................10-55Other Attitude and Directional Systems .............10-55

Common Gyroscopic Instruments .............................10-56Vacuum-Driven Attitude Gyros .............................10-56Electric Attitude Indicators ....................................10-57Gyroscopic Direction Indicator or Directional Gyro (DG) ..............................................................10-58Turn Coordinators ..................................................10-58Turn-and-Slip Indicator .........................................10-58

Autopilot Systems ......................................................10-60Basis for Autopilot Operation ................................10-60

Autopilot Components ...............................................10-61Sensing Elements ...................................................10-61Computer and Amplifier .........................................10-61Output Elements .....................................................10-61Command Elements ...............................................10-63Feedback or Follow-up Element ............................10-63Autopilot Functions ................................................10-64Yaw Dampening .....................................................10-65

Automatic Flight Control System (AFCS) ................10-65Flight Director Systems .............................................10-65Electronic Instruments ...............................................10-67

Electronic Attitude Director Indicator (EADI) ......10-67Electronic Horizontal Situation Indicators (EHSI) ...................................................10-68

Electronic Flight Information Systems ......................10-68Electronic Flight Instrument System (EFIS) ..........10-70Electronic Centralized Aircraft Monitor (ECAM) ..................................................................10-71Engine Indicating and Crew Alerting System (EICAS) .....................................................10-72

Flight Management System (FMS) ............................10-73Warnings and Cautions ..............................................10-74

Annunciator Systems ..............................................10-74Aural Warning Systems..........................................10-75

Clocks ........................................................................10-76Instrument Housings and Handling ...........................10-77Instrument Installations and Markings .......................10-78

Instrument Panels ...................................................10-78Instrument Mounting ..............................................10-80Instrument Power Requirements ............................10-81Instrument Range Markings ...................................10-81

Maintenance of Instruments and Instrument Systems ......................................................................10-81

Altimeter Tests .......................................................10-82Pitot-Static System Maintenance and Tests ...........10-83Tachometer Maintenance .......................................10-84Magnetic Compass Maintenance and Compensation .........................................................10-84Vacuum System Maintenance ................................10-85

Autopilot System Maintenance ..............................10-85LCD Display Screens .............................................10-86

Chapter 11Communication and Navigation .......................11-1Introduction ..................................................................11-1

Avionics in Aviation Maintenance ...........................11-2History of Avionics ..................................................11-2Fundamentals of Electronics ....................................11-3

Analog Versus Digital Electronics .......................11-3Analog Electronics ................................................11-4Digital Electronics .............................................11-26

Radio Communication ...............................................11-30Radio Waves...........................................................11-31

Types of Radio Waves ........................................11-32Loading Information onto a Radio Wave ...............11-32

Amplitude Modulation (AM) .............................11-34Frequency Modulation (FM) ..............................11-35Single Side Band (SSB) .....................................11-36

Radio Transmitters and Receivers ..........................11-37Transmitters ........................................................11-37Receivers .............................................................11-37Transceivers ........................................................11-38

Antennas .................................................................11-38Length .................................................................11-38Polarization, Directivity, and Field Pattern ........11-39Types ...................................................................11-40Transmission Lines .............................................11-41

Radio Navigation .......................................................11-41VOR Navigation System ........................................11-42Automatic Direction Finder (ADF) ........................11-46Radio Magnetic Indicator (RMI) ............................11-48Instrument Landing Systems (ILS) ........................11-49

Localizer .............................................................11-49 Glideslope ..........................................................11-49Compass Locators ...............................................11-51Marker Beacons ..................................................11-52

Distance Measuring Equipment (DME) .................11-52Area Navigation (RNAV) ......................................11-54Radar Beacon Transponder ....................................11-54

Transponder Tests and Inspections .....................11-58Altitude Encoders ...............................................11-58

Collision Avoidance Systems .................................11-58Traffic Collision Avoidance Systems (TCAS) ..11-59ADS-B ................................................................11-60

Radio Altimeter ......................................................11-62Weather Radar ........................................................11-64Emergency Locator Transmitter (ELT) ..................11-66

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Long Range Aid to Navigation System (LORAN) ...............................................................11-69Global Positioning System (GPS) ..........................11-69

Wide Area Augmentation System (WAAS) .......11-71Inertial Navigation System (INS)/Inertial Reference System (IRS) ..............................................................11-71Installation of Communication and Navigation Equipment ..................................................................11-72

Approval of New Avionics Equipment Installations ............................................................11-72Considerations ........................................................11-72Cooling and Moisture ............................................11-73Vibration Isolation ..................................................11-73

Reducing Radio Interference .....................................11-74Shielding ................................................................11-74Isolation ..................................................................11-74Bonding .................................................................11-74Static Discharge Wicks ..........................................11-75

Installation of Aircraft Antenna Systems ...................11-75Transmission Lines ................................................11-76Maintenance Procedure ..........................................11-76

Chapter 12Hydraulic and Pneumatic Power Systems ......12-1Aircraft Hydraulic Systems ..........................................12-1Hydraulic Fluid ............................................................12-2

Viscosity ...................................................................12-2Chemical Stability ....................................................12-2Flash Point ................................................................12-3Fire Point ..................................................................12-3

Types of Hydraulic Fluids ...........................................12-3Mineral-Based Fluids ...............................................12-3Polyalphaolefin-Based Fluids ...................................12-3Phosphate Ester-Based Fluid (Skydrol®) .................12-3Intermixing of Fluids ................................................12-3Compatibility with Aircraft Materials ......................12-3Hydraulic Fluid Contamination ................................12-4

Contamination Check ..........................................12-4Contamination Control .........................................12-5

Hydraulic System Flushing ......................................12-5Health and Handling .................................................12-5

Basic Hydraulic Systems ............................................12-6Open Center Hydraulic Systems ..............................12-6Closed-Center Hydraulic Systems............................12-7

Hydraulic Power Systems ............................................12-7Evolution of Hydraulic Systems...............................12-7Hydraulic Power Pack System .................................12-7Hydraulic System Components ................................12-8

Reservoirs .............................................................12-8Filters ......................................................................12-12

Micron-Type Filters ............................................12-14

Maintenance of Filters ........................................12-14Filter Bypass Valve ............................................12-14Filter Differential Pressure Indicators ...............12-14

Pumps .....................................................................12-15Hand Pumps ..........................................................12-15Power-Driven Pumps .............................................12-16

Classification of Pumps ......................................12-16Constant-Displacement Pumps ...........................12-17Gear-Type Power Pump .....................................12-17Gerotor Pump ......................................................12-17Piston Pump ........................................................12-18Vane Pump ..........................................................12-19Variable-Displacement Pump ............................12-20

Valves ....................................................................12-23Flow Control Valves ...........................................12-23Pressure Control Valves .....................................12-27Shuttle Valves .....................................................12-29

Accumulators..........................................................12-30Types of Accumulators .......................................12-30

Heat Exchangers .....................................................12-32Actuators ................................................................12-32

Linear Actuators .................................................12-32Rotary Actuators .................................................12-33Hydraulic Motor ................................................12-34

Ram Air Turbine (RAT) ........................................12-35Power Transfer Unit (PTU) ....................................12-35Hydraulic Motor-Driven Generator (HMDG) ........12-35Seals .......................................................................12-35

V-Ring Packings .................................................12-35U-Ring ...............................................................12-35O-Rings ...............................................................12-35Backup Rings ......................................................12-37Gaskets ................................................................12-37Seal Materials .....................................................12-37O-Ring Installation ............................................12-38Wipers ................................................................12-38

Large Aircraft Hydraulic Systems .............................12-38Boeing 737 Next Generation Hydraulic System ....12-38

Reservoirs ...........................................................12-38Pumps .................................................................12-38Filter Units ..........................................................12-40Power Transfer Unit (PTU) ................................12-40Landing Gear Transfer Unit ................................12-41Standby Hydraulic System .................................12-42Indications ...........................................................12-42

Boeing 777 Hydraulic System ................................12-42Left and Right System Description .....................12-43Center Hydraulic System ....................................12-45

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Aircraft Pneumatic Systems .......................................12-47High-Pressure Systems ...........................................12-48

Pneumatic System Components .........................12-48Emergency Backup Systems ...............................12-51

Medium-Pressure Systems .....................................12-52Low-Pressure Systems ..........................................12-52Pneumatic Power System Maintenance .................12-52

Chapter 13Aircraft Landing Gear Systems ........................13-1Landing Gear Types .....................................................13-1

Landing Gear Arrangement ......................................13-2Tail Wheel-Type Landing Gear ...........................13-3Tandem Landing Gear ..........................................13-3Tricycle-Type Landing Gear ................................13-3

Fixed and Retractable Landing Gear ........................13-5Shock Absorbing and Non-Shock Absorbing Landing Gear ...........................................................13-5

Leaf-Type Spring Gear .........................................13-6Rigid ....................................................................13-6Bungee Cord .........................................................13-7Shock Struts .........................................................13-7

Shock Strut Operation ............................................13-11Servicing Shock Struts ...........................................13-12Bleeding Shock Struts ............................................13-13

Landing Gear Alignment, Support, and Retraction ...13-14Alignment ...............................................................13-14Support ...................................................................13-15Small Aircraft Retraction Systems .........................13-16Large Aircraft Retraction Systems ........................13-20Emergency Extension Systems ..............................13-22Landing Gear Safety Devices .................................13-22

Safety Switch ......................................................13-22Ground Locks .....................................................13-23Landing Gear Position Indicators .......................13-24Nose Wheel Centering ........................................13-24

Landing Gear System Maintenance ...........................13-25Landing Gear Rigging and Adjustment..................13-26

Gear Door Clearances .........................................13-28Drag and Side Brace Adjustment ......................13-28Landing Gear Retraction Test ............................13-29

Nose Wheel Steering Systems ...................................13-30Small Aircraft ........................................................13-30Large Aircraft .........................................................13-30Shimmy Dampers ...................................................13-32

Steering Damper .................................................13-33Piston-Type .........................................................13-33Vane-Type ..........................................................13-33Non-Hydraulic Shimmy Damper ........................13-34

Aircraft Wheels ..........................................................13-34Wheel Construction ................................................13-34

Inboard Wheel Half ............................................13-35Outboard Wheel Half ..........................................13-35

Wheel Inspection ....................................................13-35On Aircraft Inspection ........................................13-35Proper Installation ...............................................13-35Off Aircraft Wheel Inspection ...........................13-37

Aircraft Brakes ...........................................................13-42Types and Construction of Aircraft Brakes ...........13-43

Single Disc Brakes ..............................................13-43Dual-Disc Brakes ................................................13-45Multiple-Disc Brakes ..........................................13-46Segmented Rotor-Disc Brakes ...........................13-47Carbon Brakes ....................................................13-50Expander Tube Brakes ........................................13-50

Brake Actuating Systems .......................................13-52Independent Master Cylinders ...........................13-52Boosted Brakes ...................................................13-55Power Brakes .....................................................13-56

Emergency Brake Systems ....................................13-59Parking Brake .....................................................13-61Brake Deboosters ................................................13-61

Anti-Skid ................................................................13-61System Operation ................................................13-61Wheel Speed Sensors ..........................................13-62Control Units ......................................................13-63Anti-Skid Control Valves ...................................13-64Touchdown and Lock Wheel Protection ............13-66Auto Brakes ........................................................13-66Anti-Skid System Tests ......................................13-66Anti-Skid System Maintenance ..........................13-68

Brake Inspection and Service .................................13-68On Aircraft Servicing .........................................13-68Lining Wear ........................................................13-68Air in the Brake System ......................................13-69Bleeding Master Cylinder Brake Systems ..........13-69Bleeding Power Brake Systems ..........................13-71Off Aircraft Brake Servicing and Maintenance ..13-72Replacement of Brake Linings ...........................13-73

Brake Malfunctions and Damage ..........................13-74Overheating ........................................................13-74Dragging ............................................................13-75Chattering or Squealing .....................................13-76

Aircraft Tires and Tubes ............................................13-76Tire Classification...................................................13-76

Types ...................................................................13-76Ply Rating ...........................................................13-77

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Tube-Type or Tubeless .......................................13-77Bias Ply or Radial ...............................................13-78

Tire Construction ....................................................13-78Bead ...................................................................13-78Carcass Plies .......................................................13-79Tread ...................................................................13-79Sidewall ..............................................................13-80

Tire Inspection on the Aircraft ...............................13-80Inflation ...............................................................13-80Tread Condition ..................................................13-82Sidewall Condition .............................................13-86

Tire Removal ..........................................................13-86Tire Inspection Off of the Aircraft .........................13-88Tire Repair and Retreading ....................................13-88Tire Storage ...........................................................13-89Aircraft Tubes.........................................................13-89

Tube Construction and Selection ........................13-89Tube Storage and Inspection ..............................13-90Tire Inspection ...................................................13-90

Tire Mounting ........................................................13-90Tubeless Tires .....................................................13-90Tube-Type Tires .................................................13-91

Tire Balancing .......................................................13-93Operation and Handling Tips .....................................13-93

Taxiing ..................................................................13-94Braking and Pivoting ..............................................13-94Landing Field and Hangar Floor Condition ..........13-94Takeoffs and Landings ...........................................13-94Hydroplaning ..........................................................13-94

Chapter 14Aircraft Fuel System..........................................14-1Basic Fuel System Requirements .................................14-1

Fuel System Independence .......................................14-2Fuel System Lightning Protection ............................14-2Fuel Flow ..................................................................14-3Flow Between Interconnected Tanks .......................14-3Unusable Fuel Supply ..............................................14-3Fuel System Hot Weather Operation........................14-3

Fuel Tanks ....................................................................14-3Fuel Tank Tests ........................................................14-3Fuel Tank Installation ...............................................14-4Fuel Tank Expansion Space .....................................14-4Fuel Tank Sump .......................................................14-4Fuel Tank Filler Connection.....................................14-4Fuel Tank Vents and Carburetor Vapor Vents .........14-4Fuel Tank Outlet .......................................................14-5Pressure Fueling Systems .........................................14-5Fuel Pumps ..............................................................14-5Fuel System Lines and Fittings ...............................14-5Fuel System Components .........................................14-5

Fuel Valves and Controls .........................................14-5Fuel Strainer or Filter ...............................................14-6Fuel System Drains ..................................................14-6Fuel Jettisoning System ............................................14-6

Types of Aviation Fuel ................................................14-7Reciprocating Engine Fuel—AVGAS .....................14-7

Volatility ...............................................................14-7Vapor Lock ...........................................................14-7Carburetor Icing ....................................................14-7Aromatic Fuels ......................................................14-8Detonation .............................................................14-8Surface Ignition and Preignition ...........................14-9Octane and Performance Number Rating .............14-9Fuel Identification ...............................................14-10Purity ...................................................................14-10

Turbine Engine Fuels .............................................14-11Turbine Fuel Volatility .......................................14-12Turbine Engine Fuel Types ................................14-13Turbine Engine Fuel Issues ................................14-13

Aircraft Fuel Systems ................................................14-13Small Single-Engine Aircraft Fuel Systems ...........14-13

Gravity Feed Systems .........................................14-13Pump Feed Systems ............................................14-14High-Wing Aircraft With Fuel Injection System .................................................................14-14

Small Multiengine (Reciprocating) Aircraft Fuel Systems ..........................................................14-15

Low-Wing Twin .................................................14-15High-Wing Twin .................................................14-16

Large Reciprocating-Engine Aircraft Fuel Systems ...................................................................14-16Jet Transport Aircraft Fuel Systems .......................14-17Helicopter Fuel Systems .........................................14-22

Fuel System Components ..........................................14-22Fuel Tanks ..............................................................14-22

Rigid Removable Fuel Tanks .............................14-23Bladder Fuel Tanks .............................................14-25Integral Fuel Tanks .............................................14-25

Fuel Lines and Fittings ...........................................14-26Fuel Valves ............................................................14-26

Hand-Operated Valves ........................................14-28Cone Valves ........................................................14-28Poppet Valves .....................................................14-29Manually-Operated Gate Valves ........................14-29Motor-Operated Valves ......................................14-30Solenoid-Operated Valves ..................................14-31

Fuel Pumps .............................................................14-31Hand-Operated Fuel Pumps ................................14-31Ejector Pumps .....................................................14-32

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Pulsating Electric Pumps ....................................14-34Vane-Type Fuel Pumps ......................................14-35

Fuel Filters ..............................................................14-36Fuel Heaters and Ice Prevention .............................14-39Fuel System Indicators ...........................................14-40

Fuel Quantity Indicating Systems .......................14-40Fuel Flowmeters .................................................14-44Fuel Temperature Gauges ...................................14-46Fuel Pressure Gauges ..........................................14-47Pressure Warning Signal .....................................14-48Valve-In-Transit Indicator Lights ......................14-48

Fuel System Repair ...................................................14-49Troubleshooting the Fuel System ...........................14-49

Location of Leaks and Defects ...........................14-49Fuel Leak Classification .....................................14-50Replacement of Gaskets, Seals, and Packings ....14-50

Fuel Tank Repair ....................................................14-50Welded Tanks .....................................................14-51Riveted Tanks .....................................................14-51Soldered Tanks ...................................................14-51Bladder Tanks .....................................................14-51Integral Tanks .....................................................14-52Fire Safety ...........................................................14-52

Fuel System Servicing ...............................................14-54Checking for Fuel System Contaminants ...............14-54

Water ...................................................................14-54Solid Particle Contaminants ...............................14-55Surfactants ..........................................................14-55Microorganisms ..................................................14-55Foreign Fuel Contamination ...............................14-56Detection of Contaminants .................................14-56Fuel Contamination Control ...............................14-58

Fueling and Defueling Procedures .............................14-59Fueling ....................................................................14-59Defueling ................................................................14-61Fire Hazards When Fueling or Defueling ..............14-61

Chapter 15Ice and Rain Protection.....................................15-1Ice Control Systems .....................................................15-1

Icing Effects .............................................................15-2Ice Detector System .....................................................15-3

Ice Prevention ...........................................................15-3Wing and Horizontal and Vertical Stabilizer Anti-Icing Systems .......................................................15-4

Thermal Pneumatic Anti-icing .................................15-4Wing Anti-Ice (WAI) System ...............................15-4Leading Edge Slat Anti-Ice System ......................15-6

Thermal Electric Anti-Icing ...................................15-10Chemical Anti-Icing ...............................................15-10

Wing and Stabilizer Deicing Systems ........................15-12Sources of Operating Air ........................................15-12

Turbine Engine Bleed Air ...................................15-12Pneumatic Deice Boot System for GA Aircraft .....15-12

GA System Operation .........................................15-13Deice System for Turboprop Aircraft ....................15-14Deicing System Components .................................15-14

Wet-Type Engine-Driven Air Pump ...................15-14Dry-Type Engine-Driven Air Pump ...................15-16Oil Separator .......................................................15-17Control Valve ......................................................15-17Deflate Valve ......................................................15-18Distributor Valve ................................................15-18Timer/Control Unit .............................................15-18Regulators and Relief Valves .............................15-18Manifold Assembly ............................................15-19Inlet Filter ...........................................................15-19

Construction and Installation of Deice Boots.........15-19Inspection, Maintenance, and Troubleshooting of Rubber Deicer Boot Systems .............................15-19

Operational Checks .............................................15-19Adjustments ........................................................15-21Troubleshooting ..................................................15-21Inspection ............................................................15-21

Deice Boot Maintenance ........................................15-21Electric Deice Boots ...............................................15-22

Propeller Deice System ..............................................15-23Electrothermal Propeller Device System ..............15-23Chemical Propeller Deice .......................................15-23

Ground Deicing of Aircraft ........................................15-23Frost Removal ........................................................15-25

Deicing and Anti-icing of Transport Type Aircraft ................................................................15-25

Ice and Snow Removal ...........................................15-27Rain Control Systems ................................................15-27

Windshield Wiper Systems ...................................15-27Chemical Rain Repellant ........................................15-27

Windshield Surface Seal Coating .......................15-28Pneumatic Rain Removal Systems .........................15-28

Windshield Frost, Fog, and Ice Control Systems ......15-28Electric....................................................................15-28Pneumatic ...............................................................15-30Chemical .................................................................15-31

Portable Water Tank Ice Prevention ..........................15-32

Chapter 16Cabin Environmental Control Systems ...........16-1Physiology of Flight .....................................................16-1

Composition of the Atmosphere...............................16-1Human Respiration and Circulation .........................16-2

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Oxygen and Hypoxia ............................................16-2Carbon Monoxide Poisoning ................................16-3

Aircraft Oxygen Systems .............................................16-3Forms of Oxygen and Characteristics ......................16-4

Gaseous Oxygen ...................................................16-4Liquid Oxygen ......................................................16-4Chemical or Solid Oxygen ...................................16-5Onboard Oxygen Generating Systems (OBOGS) ..............................................................16-5

Oxygen Systems and Components ...........................16-6Gaseous Oxygen Systems .....................................16-6Chemical Oxygen Systems .................................16-16LOX Systems ......................................................16-16

Oxygen System Servicing ......................................16-16Servicing Gaseous Oxygen .................................16-16Filling LOX Systems ..........................................16-19Inspection of Masks and Hoses ..........................16-19Replacing Tubing, Valves, and Fittings .............16-20

Prevention of Oxygen Fires or Explosions.............16-20Oxygen System Inspection and Maintenance .....16-20

Aircraft Pressurization Systems .................................16-21Pressure of the Atmosphere ....................................16-21Temperature and Altitude .......................................16-22Pressurization Terms ..............................................16-23Pressurization Issues...............................................16-23Sources of Pressurized Air .....................................16-24

Reciprocating Engine Aircraft ...........................16-25Turbine Engine Aircraft .....................................16-26

Control of Cabin Pressure .....................................16-27Pressurization Modes ..........................................16-27Cabin Pressure Controller ...................................16-28Cabin Air Pressure Regulator and Outflow Valve ...................................................................16-30Cabin Air Pressure Safety Valve Operation .......16-31Pressurization Gauges .........................................16-32Pressurization Operation ....................................16-32Air Distribution ...................................................16-34Cabin Pressurization Troubleshooting ................16-34

Air Conditioning Systems ..........................................16-34Air Cycle Air Conditioning ....................................16-35

System Operation ................................................16-36Pneumatic System Supply ..................................16-36Component Operation .........................................16-36Water Separator ..................................................16-39Cabin Temperature Control System ...................16-39

Vapor Cycle Air Conditioning ...............................16-40Theory of Refrigeration ......................................16-41Vapor Cycle Air Conditioning System Components ........................................................16-46

Vapor Cycle Air Conditioning Servicing Equipment ...........................................................16-51System Servicing ................................................16-55Technician Certification ......................................16-58

Aircraft Heaters ..........................................................16-58Bleed Air Systems ..................................................16-58Electric Heating Systems........................................16-58Exhaust Shroud Heaters .........................................16-58Combustion Heaters ...............................................16-60

Combustion Air System ......................................16-60Ventilating Air System ......................................16-60Fuel System ........................................................16-61Ignition System ...................................................16-61Controls ...............................................................16-61Safety Features ...................................................16-62Maintenance and Inspection ...............................16-62

Chapter 17Fire Protection Systems ...................................17-1Introduction ..................................................................17-1

Classes of Fires .........................................................17-2Requirements for Overheat and Fire Protection Systems .....................................................................17-2

Fire Detection/Overheat Systems ................................17-2Thermal Switch System............................................17-2Thermocouple System ..............................................17-3Continuous-Loop Systems .......................................17-4

Fenwal System ......................................................17-4Kidde System ........................................................17-4

Pressure Type Sensor Responder Systems ...............17-6Pneumatic Continuous-Loop Systems ..................17-6

Fire Zones .................................................................17-8Smoke, Flame, and Carbon Monoxide Detection Systems ........................................................................17-8

Smoke Detectors.......................................................17-8Light Refraction Type ...........................................17-8Ionization Type .....................................................17-8

Flame Detectors ........................................................17-9Carbon Monoxide Detectors ....................................17-9

Extinguishing Agents and Portable Fire Extinguishers ..............................................................17-10

Halogenated Hydrocarbons ....................................17-10Inert Cold Gases .....................................................17-10Dry Powders ...........................................................17-10Water ......................................................................17-11Cockpit and Cabin Interiors ...................................17-11

Extinguisher Types .............................................17-11Installed Fire Extinguishing Systems .........................17-11

CO2 Fire Extinguishing Systems ............................17-11

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Halogenated Hydrocarbons Fire Extinguishing Systems ...................................................................17-11Containers ..............................................................17-12Discharge Valves ....................................................17-13Pressure Indication .................................................17-13Two-Way Check Valve ..........................................17-13Discharge Indicators ...............................................17-13

Thermal Discharge Indicator (Red Disk) ...........17-13Yellow Disk Discharge Indicator .......................17-14

Fire Switch .............................................................17-14Cargo Fire Detection ..................................................17-14

Cargo Compartment Classification ........................17-15Class A ................................................................17-15Class B ................................................................17-15Class C ................................................................17-15Class E ................................................................17-15

Cargo and Baggage Compartment Fire Detection and Extinguisher System .......................17-15

Smoke Detector System ......................................17-16Cargo Compartment Extinguishing System .......17-16

Lavatory Smoke Detectors .........................................17-17Lavatory Smoke Detector System .........................17-17Lavatory Fire Extinguisher System ........................17-18

Fire Detection System Maintenance ..........................17-18Fire Detection System Troubleshooting ....................17-19Fire Extinguisher System Maintenance .....................17-20

Container Pressure Check ......................................17-20Discharge Cartridges ..............................................17-20Agent Containers ....................................................17-20

Fire Prevention ...........................................................17-21

Glossary ..............................................................G-1

Index ......................................................................I-1

10-2

Figure 10-2. A conventional instrument panel of the C-5A Galaxy (top) and the glass cockpit of the C-5B Galaxy (bottom).

Figure 10-1. From top to bottom: instruments of the Wright Flyer, instruments on a World War I era aircraft, a late 1950s/early 1960s Boeing 707 airliner cockpit, and an Airbus A380 glass cockpit.

The ability to capture and convey all of the information a pilot may want, in an accurate, easily understood manner, has been a challenge throughout the history of aviation. As the range of desired information has grown, so too have the size and complexity of modern aircraft, thus expanding even further the need to inform the flight crew without sensory overload or overcluttering the cockpit. As a result, the old flat panel in the front of the cockpit with various individual instruments attached to it has evolved into a sophisticated computer-controlled digital interface with flat-panel display screens and prioritized messaging. A visual comparison between a conventional cockpit and a glass cockpit is shown in Figure 10-2.

There are usually two parts to any instrument or instrument system. One part senses the situation and the other part displays it. In analog instruments, both of these functions often take place in a single unit or instrument (case). These are called direct-sensing instruments. Remote-sensing requires the information to be sensed, or captured, and then sent to a separate display unit in the cockpit. Both analog and digital instruments make use of this method. [Figure 10-3]

10-3

Figure 10-3. There are two parts to any instrument system—the sensing mechanism and the display mechanism.

Sensor + Indication Sensor Indication

Direct-sensing instrument system

Remote-sensing instrument system

Figure 10-4. The basic T arrangement of analog flight instruments. At the bottom of the T is a heading indicator that functions as a compass but is driven by a gyroscope and not subject to the oscillations common to magnetic direction indicators.

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The relaying of important bits of information can be done in various ways. Electricity is often used by way of wires that carry sensor information into the cockpit. Sometimes pneumatic lines are used. In complex, modern aircraft, this can lead to an enormous amount of tubing and wiring terminating behind the instrument display panel. More efficient information transfer has been accomplished via the use of digital data buses. Essentially, these are wires that share message carrying for many instruments by digitally encoding the signal for each. This reduces the number of wires and weight required to transfer remotely sensed information for the pilot’s use. Flat-panel computer display screens that can be controlled to show only the information desired are also lighter in weight than the numerous individual gauges it would take to display the same information simultaneously. An added bonus is the increased reliability inherent in these solid-state systems.

It is the job of the aircraft technician to understand and maintain all aircraft, including these various instrument systems. Accordingly, in this chapter, discussions begin with analog instruments and refer to modern digital instrumentation when appropriate.

Classifying InstrumentsThere are three basic kinds of instruments classified by the job they perform: flight instruments, engine instruments, and navigation instruments. There are also miscellaneous gauges and indicators that provide information that do not fall into these classifications, especially on large complex aircraft. Flight control position, cabin environmental systems, electrical power, and auxiliary power units (APUs), for example, are all monitored and controlled from the cockpit via the use of instruments systems. All may be regarded as position/condition instruments since they usually report the position of a certain moveable component on the aircraft, or the condition of various aircraft components or systems not included in the first three groups.

Flight InstrumentsThe instruments used in controlling the aircraft’s flight attitude are known as the flight instruments. There are basic flight instruments, such as the altimeter that displays aircraft altitude; the airspeed indicator; and the magnetic direction

indicator, a form of compass. Additionally, an artificial horizon, turn coordinator, and vertical speed indicator are flight instruments present in most aircraft. Much variation exists for these instruments, which is explained throughout this chapter. Over the years, flight instruments have come to be situated similarly on the instrument panels in most aircraft. This basic T arrangement for flight instruments is shown in Figure 10-4. The top center position directly in front of the pilot and copilot is the basic display position for the artificial horizon even in modern glass cockpits (those with solid-state, flat-panel screen indicating systems).

Original analog flight instruments are operated by air pressure and the use of gyroscopes. This avoids the use of electricity, which could put the pilot in a dangerous situation if the aircraft lost electrical power. Development of sensing and display techniques, combined with advanced aircraft electrical systems, has made it possible for reliable primary and secondary instrument systems that are electrically operated. Nonetheless, often a pneumatic altimeter, a gyro artificial horizon, and a magnetic direction indicator are retained somewhere in the instrument panel for redundancy. [Figure 10-5]

Engine InstrumentsEngine instruments are those designed to measure operating parameters of the aircraft’s engine(s). These are usually quantity, pressure, and temperature indications. They also include measuring engine speed(s). The most common engine instruments are the fuel and oil quantity and pressure gauges, tachometers, and temperature gauges. Figure 10-6 contains various engine instruments found on reciprocating and turbine-powered aircraft.

10-4

Figure 10-7. An engine instrumentation located in the middle of the instrument panel is shared by the pilot and co-pilot.

Figure 10-5. This electrically operated flat screen display instrument panel, or glass cockpit, retains an analog airspeed indicator, a gyroscope-driven artificial horizon, and an analog altimeter as a backup should electric power be lost, or a display unit fails.

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Figure 10-6. Common engine instruments. Note: For example purposes only. Some aircraft may not have these instruments or may be equipped with others.

Reciprocating engines

Oil pressure Oil pressureOil temperature Exhaust gas temperature (EGT)Cylinder head temperature (CHT) Turbine inlet temperature (TIT) or turbine gas temperature (TGT)Manifold pressure Engine pressure ratio (EPR)Fuel quantity Fuel quantityFuel pressure Fuel pressure Fuel flowTachometer Tachometer (percent calibrated) N1 and N2 compressor speedsCarburetor temperature Torquemeter (on turboprop and turboshaft engines)

Turbine engines

Engine instrumentation is often displayed in the center of the cockpit where it is easily visible to the pilot and copilot. [Figure 10-7] On light aircraft requiring only one flight crewmember, this may not be the case. Multiengine aircraft often use a single gauge for a particular engine parameter,

but it displays information for all engines through the use of multiple pointers on the same dial face.

Navigation InstrumentsNavigation instruments are those that contribute information used by the pilot to guide the aircraft along a definite course. This group includes compasses of various kinds, some of which incorporate the use of radio signals to define a specific course while flying the aircraft en route from one airport to another. Other navigational instruments are designed specifically to direct the pilot’s approach to landing at an airport. Traditional navigation instruments include a clock and a magnetic compass. Along with the airspeed indicator and wind information, these can be used to calculate navigational progress. Radios and instruments sending locating information via radio waves have replaced these manual efforts in modern aircraft. Global position systems (GPS) use satellites to pinpoint the location of the aircraft via geometric triangulation. This technology is built into some aircraft instrument packages for navigational purposes.