Aviation Maintenance Technician Handbook – AirframeVolume 12012

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-8083-31V1-PD978-1-56027-951-8

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

xiii

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

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

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

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

Chapter 1Aircraft Structures ...............................................1-1A Brief History of Aircraft Structures ...........................1-1General ...........................................................................1-5Major Structural Stresses ...............................................1-6Fixed-Wing Aircraft .......................................................1-8

Fuselage ......................................................................1-8Truss Type ..............................................................1-8Monocoque Type ....................................................1-9Semimonocoque Type ............................................1-9

Pressurization ..........................................................1-10Wings ...........................................................................1-10

Wing Configurations ................................................1-10Wing Structure .........................................................1-11Wing Spars ...............................................................1-13Wing Ribs .................................................................1-15Wing Skin .................................................................1-17Nacelles ....................................................................1-19

Empennage ..................................................................1-22Flight Control Surfaces ................................................1-24

Primary Flight Control Surfaces...............................1-24Ailerons .................................................................1-26Elevator .................................................................1-27Rudder ..................................................................1-27

Dual Purpose Flight Control Surfaces ......................1-27Secondary or Auxiliary Control Surfaces ...............1-28

Flaps ......................................................................1-28Slats ......................................................................1-30Spoilers and Speed Brakes ....................................1-30Tabs ......................................................................1-31

Other Wing Features ................................................1-34Landing Gear ...............................................................1-35

Tail Wheel Gear Configuration ................................1-37Tricycle Gear ............................................................1-38

Maintaining the Aircraft ..............................................1-38Location Numbering Systems ..................................1-39Access and Inspection Panels ...................................1-40

Helicopter Structures ...................................................1-40Airframe ...................................................................1-40Fuselage ....................................................................1-42Landing Gear or Skids ..............................................1-42Powerplant and Transmission ..................................1-42

Turbine Engines ....................................................1-42Transmission .........................................................1-43

Main Rotor System ...................................................1-43Rigid Rotor System ...............................................1-44Semirigid Rotor System ........................................1-44

Fully Articulated Rotor System ................................1-44Antitorque System ....................................................1-45Controls ....................................................................1-46

Chapter 2Aerodynamics, Aircraft Assembly, and Rigging .................................................................2-1Introduction ....................................................................2-1Basic Aerodynamics .....................................................2-2The Atmosphere .............................................................2-2

Pressure ......................................................................2-2Density .......................................................................2-3Humidity .....................................................................2-3

Aerodynamics and the Laws of Physics ........................2-3Velocity and Acceleration ..........................................2-3Newton’s Laws of Motion ..........................................2-4Bernoulli’s Principle and Subsonic Flow ...................2-4

Airfoil .............................................................................2-5Shape of the Airfoil ....................................................2-5Angle of Incidence .....................................................2-6Angle of Attack (AOA) ..............................................2-6Boundary Layer ..........................................................2-7

Thrust and Drag .............................................................2-7Center of Gravity (CG) ..................................................2-9The Axes of an Aircraft ................................................2-9

Table of Contents

xiv

Stability and Control .....................................................2-9Static Stability ............................................................2-9Dynamic Stability .....................................................2-11Longitudinal Stability ...............................................2-11Directional Stability .................................................2-11Lateral Stability ........................................................2-11Dutch Roll ................................................................2-11

Primary Flight Controls ...............................................2-12Trim Controls ...............................................................2-12Auxiliary Lift Devices .................................................2-13

Winglets ...................................................................2-14Canard Wings ...........................................................2-14Wing Fences ............................................................2-14

Control Systems for Large Aircraft .............................2-14Mechanical Control ..................................................2-14Hydromechanical Control ........................................2-15Fly-By-Wire Control ...............................................2-15

High-Speed Aerodynamics ..........................................2-15Rotary-Wing Aircraft Assembly and Rigging .............2-16Configurations of Rotary-Wing Aircraft ......................2-18

Autogyro ...................................................................2-18Single Rotor Helicopter ............................................2-18Dual Rotor Helicopter ..............................................2-18

Types of Rotor Systems ...............................................2-18Fully Articulated Rotor ............................................2-18Semirigid Rotor ........................................................2-19Rigid Rotor ...............................................................2-19

Forces Acting on the Helicopter ..................................2-19Torque Compensation ..............................................2-19Gyroscopic Forces ....................................................2-20

Helicopter Flight Conditions .......................................2-22Hovering Flight ........................................................2-22

Translating Tendency or Drift ..............................2-22Ground Effect .......................................................2-23Coriolis Effect (Law of Conservation of Angular Momentum) ...........................................2-23

Vertical Flight...........................................................2-24Forward Flight ..........................................................2-24

Translational Lift ..................................................2-24Effective Translational Lift (ETL) ........................2-25Dissymmetry of Lift .............................................2-26

Autorotation .............................................................2-28Rotorcraft Controls ......................................................2-29

Swash Plate Assembly .............................................2-29Collective Pitch Control ...........................................2-29Throttle Control ........................................................2-30Governor/Correlator ................................................2-30Cyclic Pitch Control .................................................2-30Antitorque Pedals .....................................................2-31

Stabilizer Systems ........................................................2-31Bell Stabilizer Bar System .......................................2-31

Offset Flapping Hinge ..............................................2-32Stability Augmentation Systems (SAS) ...................2-32Helicopter Vibration .................................................2-32

Extreme Low Frequency Vibration ......................2-32Low Frequency Vibration .....................................2-32Medium Frequency Vibration ...............................2-32High Frequency Vibration ....................................2-32

Rotor Blade Tracking ...............................................2-32Flag and Pole ........................................................2-32Electronic Blade Tracker ......................................2-33

Tail Rotor Tracking ..................................................2-34Marking Method ...................................................2-34Electronic Method ................................................2-34

Rotor Blade Preservation and Storage......................2-35Helicopter Power Systems ...........................................2-35

Powerplant ................................................................2-35Reciprocating Engine ...............................................2-35Turbine Engine .........................................................2-36

Transmission System ...................................................2-36Main Rotor Transmission .........................................2-36Clutch .......................................................................2-37

Centrifugal Clutch ................................................2-37Belt Drive Clutch ..................................................2-37

Freewheeling Unit ....................................................2-38Airplane Assembly and Rigging ..............................2-38Rebalancing of Control Surfaces ..............................2-38

Static Balance .......................................................2-38Dynamic Balance ..................................................2-38

Rebalancing Procedures ..........................................2-39Rebalancing Methods ...............................................2-40

Aircraft Rigging ...........................................................2-41Rigging Specifications ..............................................2-41

Type Certificate Data Sheet ..................................2-41Maintenance Manual ............................................2-41Structural Repair Manual (SRM) ..........................2-41Manufacturer’s Service Information .....................2-41

Airplane Assembly ..................................................2-41Aileron Installation ..............................................2-41Flap Installation ....................................................2-41Empennage Installation ........................................2-41

Control Operating Systems ......................................2-41Cable Systems .......................................................2-41Cable Inspection ...................................................2-44Cable System Installation .....................................2-44Push Rods (Control Rods) ....................................2-47Torque Tubes ........................................................2-48Cable Drums .........................................................2-48

Rigging Checks ........................................................2-48Structural Alignment ............................................2-48

xv

Cable Tension .......................................................2-52Control Surface Travel .........................................2-53Checking and Safetying the System .....................2-55

Biplane Assembly and Rigging ................................2-58Aircraft Inspection .......................................................2-60

Purpose of Inspection Programs ..............................2-60Perform an Airframe Conformity and Airworthiness Inspection ..........................................2-61Required Inspections ................................................2-61

Preflight .................................................................2-61Periodic Maintenance Inspections: .......................2-61Altimeter and Static System Inspections ..............2-63Air Traffic Control (ATC) Transponder Inspections ............................................................2-63Emergency Locator Transmitter (ELT) Operational and Maintenance Practices in Accordance With Advisory Circular (AC) 91-44 ....................................................................2-64

Annual and 100-Hour Inspections ............................2-64Preparation ............................................................2-64

Other Aircraft Inspection and Maintenance Programs ...................................................................2-66

Continuous Airworthiness Maintenance Program (CAMP) ..................................................2-68Title 14 CFR part 125, section 125.247, Inspection Programs and Maintenance .................2-68Helicopter Inspections, Piston-Engine and Turbine-Powered ..................................................2-69Light-Sport Aircraft, Powered Parachute, and Weight-Shift Control Aircraft ..............................2-69

Chapter 3Aircraft Fabric Covering .....................................3-1General History ..............................................................3-1Fabric Terms ..................................................................3-3Legal Aspects of Fabric Covering .................................3-3Approved Materials ......................................................3-4

Fabric .........................................................................3-4Other Fabric Covering Materials ................................3-5

Anti-Chafe Tape .....................................................3-5Reinforcing Tape ....................................................3-5Rib Bracing .............................................................3-5Surface Tape ...........................................................3-5Rib Lacing Cord .....................................................3-5Sewing Thread ........................................................3-6Special Fabric Fasteners .........................................3-6Grommets ...............................................................3-6Inspection Rings .....................................................3-6Primer .....................................................................3-7

Fabric Cement .........................................................3-7Fabric Sealer ...........................................................3-8Fillers ......................................................................3-8Topcoats ..................................................................3-8

Available Covering Processes ........................................3-8Determining Fabric Condition—Repair or Recover? ....3-9Fabric Strength ...............................................................3-9

How Fabric Breaking Strength is Determined .........3-10Fabric Testing Devices .............................................3-11

General Fabric Covering Process .................................3-11Blanket Method vs. Envelope Method ....................3-12Preparation for Fabric Covering Work .....................3-12Removal of Old Fabric Coverings............................3-13Preparation of the Airframe Before Covering ..........3-14Attaching Polyester Fabric to the Airframe .............3-15

Seams ....................................................................3-16Fabric Cement .......................................................3-16Fabric Heat Shrinking ...........................................3-17Attaching Fabric to the Wing Ribs .......................3-18Rib Lacing ............................................................3-18Rings, Grommets, and Gussets ............................3-21Finishing Tapes .....................................................3-21Coating the Fabric .................................................3-22

Polyester Fabric Repairs .............................................3-23Applicable Instructions.............................................3-23Repair Considerations ..............................................3-23

Cotton-Covered Aircraft ..............................................3-23Fiberglass Coverings ....................................................3-24

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

Stresses in Structural Members ..................................4-2Tension ...................................................................4-2Compression ...........................................................4-3Shear .......................................................................4-3Bearing ....................................................................4-3Torsion ...................................................................4-3Bending ..................................................................4-4

Tools for Sheet Metal Construction and Repair ............4-4Layout Tools ..............................................................4-4

Scales ......................................................................4-4Combination Square ...............................................4-4Dividers ...................................................................4-4Rivet Spacers ..........................................................4-4

Marking Tools ............................................................4-4Pens .........................................................................4-4Scribes .....................................................................4-5

Punches .......................................................................4-5Prick Punch .............................................................4-6

xvi

Center Punch ...........................................................4-6Automatic Center Punch .........................................4-6Transfer Punch ........................................................4-6Drive Punch ............................................................4-6Pin Punch ................................................................4-7Chassis Punch .........................................................4-7Awl .........................................................................4-7

Hole Duplicator ..........................................................4-8Cutting Tools ..............................................................4-8

Circular-Cutting Saws ............................................4-8Kett Saw .................................................................4-8Pneumatic Circular Cutting Saw ............................4-8Reciprocating Saw ..................................................4-9Cut-off Wheel .........................................................4-9Nibblers ...................................................................4-9

Shop Tools ..................................................................4-9Squaring Shear ........................................................4-9Throatless Shear ...................................................4-10Scroll Shears .........................................................4-10Rotary Punch Press ...............................................4-10Band Saw ..............................................................4-11Disk Sander ...........................................................4-11Belt Sander ............................................................4-11Notcher .................................................................4-12Grinding Wheels ...................................................4-13

Hand Cutting Tools ..................................................4-13Straight Snips ........................................................4-13Aviation Snips ......................................................4-13Files .......................................................................4-13Die Grinder ...........................................................4-14Burring Tool .........................................................4-14

Hole Drilling ................................................................4-14Portable Power Drills ...............................................4-15

Pneumatic Drill Motors ........................................4-15Right Angle and 45° Drill Motors ........................4-15Two Hole .............................................................4-15

Drill Press .................................................................4-15Drill Extensions and Adapters .................................4-16

Extension Drill Bits ..............................................4-16Straight Extension .................................................4-16Angle Adapters ....................................................4-16Snake Attachment .................................................4-16

Types of Drill Bits ...................................................4-17Step Drill Bits .......................................................4-17Cobalt Alloy Drill Bits ..........................................4-17Twist Drill Bits .....................................................4-17

Drill Bit Sizes ...........................................................4-18Drill Lubrication .......................................................4-18

Reamers ....................................................................4-19Drill Stops ................................................................4-19Drill Bushings and Guides .......................................4-19Drill Bushing Holder Types .....................................4-19Hole Drilling Techniques .........................................4-20

Drilling Large Holes .............................................4-20Chip Chasers ............................................................4-20

Forming Tools ..............................................................4-21Bar Folding Machine ................................................4-21Cornice Brake ...........................................................4-22Box and Pan Brake (Finger Brake) ..........................4-22Press Brake ...............................................................4-22Slip Roll Former .......................................................4-23Rotary Machine ........................................................4-24Stretch Forming ........................................................4-24Drop Hammer ...........................................................4-24Hydropress Forming .................................................4-24Spin Forming ............................................................4-25Forming With an English Wheel ..............................4-26Piccolo Former .........................................................4-26Shrinking and Stretching Tools ................................4-26

Shrinking Tools ....................................................4-26Stretching Tools ....................................................4-27Manual Foot-Operated Sheet Metal Shrinker .......4-27Hand-Operated Shrinker and Stretcher .................4-27Hardwood Form Blocks ........................................4-27V-Blocks ...............................................................4-27Shrinking Blocks ..................................................4-28Sandbags ...............................................................4-28Sheet Metal Hammers and Mallets .......................4-28

Sheet Metal Holding Devices ......................................4-28Clamps and Vises ....................................................4-28

C-Clamps ..............................................................4-28Vises .....................................................................4-29

Reusable Sheet Metal Fasteners ...............................4-29Cleco Fasteners .....................................................4-29Hex Nut and Wing Nut Temporary Sheet Fasteners ...............................................................4-30

Aluminum Alloys.........................................................4-30Structural Fasteners .....................................................4-31

Solid Shank Rivet ....................................................4-31Description ............................................................4-31Installation of Rivets .............................................4-32Rivet Installation Tools .........................................4-36Riveting Procedure ..............................................4-40Countersunk Rivets ...............................................4-41Evaluating the Rivet .............................................4-44Removal of Rivets ................................................4-45Replacing Rivets ...................................................4-46

xvii

National Advisory Committee for Aeronautics (NACA) Method of Double Flush Riveting .........4-46

Special Purpose Fasteners ........................................4-47Blind Rivets ..........................................................4-47Pin Fastening Systems (High-Shear Fasteners) ...4-50Lockbolt Fastening Systems ................................4-52Blind Bolts ............................................................4-54Rivet Nut ...............................................................4-56Blind Fasteners (Nonstructural) ............................4-57

Forming Process...........................................................4-57Forming Operations and Terms ...................................4-58

Stretching .................................................................4-58Shrinking ..................................................................4-58Bumping ...................................................................4-59Crimping ...................................................................4-59Folding Sheet Metal .................................................4-59

Layout and Forming .....................................................4-59Terminology ............................................................4-59Layout or Flat Pattern Development ........................4-60Making Straight Line Bends.....................................4-61

Bending a U-Channel ...........................................4-62Using a J-Chart To Calculate Total Developed Width ....................................................................4-67How To Find the Total Developed Width Using a J-Chart ................................................................4-67

Using a Sheet Metal Brake to Fold Metal ................4-68Step 1: Adjustment of Bend Radius ......................4-68Step 2: Adjusting Clamping Pressure ...................4-70Step 3: Adjusting the Nose Gap ............................4-71

Folding a Box ...........................................................4-71Relief Hole Location .............................................4-73Layout Method ......................................................4-73

Open and Closed Bends ...........................................4-74Open End Bend (Less Than 90°) ..........................4-74Closed End Bend (More Than 90°) ......................4-74

Hand Forming ..........................................................4-74Straight Line Bends ..............................................4-75Formed or Extruded Angles ..................................4-75Flanged Angles .....................................................4-76Shrinking ...............................................................4-76Stretching ..............................................................4-77Curved Flanged Parts ............................................4-77Forming by Bumping ............................................4-80Joggling .................................................................4-81Lightening Holes ..................................................4-82

Working Stainless Steel............................................4-83Working Inconel® Alloys 625 and 718 ....................4-83Working Magnesium ................................................4-84Working Titanium ....................................................4-85

Description of Titanium ........................................4-85Basic Principles of Sheet Metal Repair .......................4-86

Maintaining Original Strength..................................4-87Shear Strength and Bearing Strength .......................4-88Maintaining Original Contour ..................................4-89Keeping Weight to a Minimum ................................4-89Flutter and Vibration Precautions.............................4-89Inspection of Damage ..............................................4-90Types of Damage and Defects..................................4-90Classification of Damage..........................................4-91

Negligible Damage ...............................................4-91Damage Repairable by Patching ...........................4-91Damage Repairable by Insertion ..........................4-92Damage Necessitating Replacement of Parts .......4-92

Repairability of Sheet Metal Structure ........................4-92Structural Support During Repair.............................4-92Assessment of Damage ............................................4-92Inspection of Riveted Joints .....................................4-92Inspection for Corrosion ...........................................4-93Damage Removal .....................................................4-93

Repair Material Selection .....................................4-93Repair Parts Layout .............................................4-93Rivet Selection .....................................................4-94Rivet Spacing and Edge Distance .........................4-94Corrosion Treatment ............................................4-94

Approval of Repair ...................................................4-94Repair of Stressed Skin Structure ............................4-95

Patches .................................................................4-95Typical Repairs for Aircraft Structures ...................4-97

Floats .....................................................................4-97Corrugated Skin Repair ........................................4-97Replacement of a Panel ........................................4-97Outside the Member ............................................4-97Inside the Member ................................................4-97Edges of the Panel ...............................................4-97Repair of Lightening Holes ................................4-100Repairs to a Pressurized Area .............................4-100Stringer Repair ....................................................4-100Former or Bulkhead Repair ................................4-102Longeron Repair .................................................4-103Spar Repair .........................................................4-103Rib and Web Repair ............................................4-104Leading Edge Repair ..........................................4-105Trailing Edge Repair ...........................................4-105Specialized Repairs .............................................4-108Inspection Openings ...........................................4-108

xviii

Chapter 5Aircraft Welding ...................................................5-1Introduction ....................................................................5-1Types of Welding ...........................................................5-2

Gas Welding ...............................................................5-2Electric Arc Welding ..................................................5-2

Shielded Metal Arc Welding (SMAW) ..................5-2

Gas Metal Arc Welding (GMAW) .........................5-3Gas Tungsten Arc Welding (GTAW) .....................5-3

Electric Resistance Welding ......................................5-5Spot Welding ..........................................................5-6Seam Welding .........................................................5-6

Plasma Arc Welding (PAW) ......................................5-6Plasma Arc Cutting ...................................................5-7

Gas Welding and Cutting Equipment ............................5-7Welding Gases ...........................................................5-7

Acetylene ................................................................5-7Argon ......................................................................5-7Helium ....................................................................5-7Hydrogen ................................................................5-7Oxygen ....................................................................5-7

Pressure Regulators ....................................................5-7Welding Hose .............................................................5-8Check Valves and Flashback Arrestors ......................5-8Torches .......................................................................5-9

Equal Pressure Torch ..............................................5-9Injector Torch .........................................................5-9Cutting Torch ..........................................................5-9

Torch Tips ..................................................................5-9Welding Eyewear .......................................................5-9

Filler Rod ..............................................................5-10Equipment Setup ......................................................5-10

Gas Cylinders ........................................................5-10Regulators .............................................................5-11Hoses .....................................................................5-11Connecting Torch .................................................5-11Select the Tip Size ................................................5-11Adjusting the Regulator Working Pressure ..........5-13

Lighting and Adjusting the Torch ...........................5-13Different Flames .......................................................5-13

Neutral Flame .......................................................5-13Carburizing Flame ................................................5-13Oxidizing Flame ...................................................5-13Soft or Harsh Flames ............................................5-13Handling of the Torch ...........................................5-14

Oxy-acetylene Cutting .................................................5-14Shutting Down the Gas Welding Equipment ...........5-15

Gas Welding Procedures and Techniques ....................5-15

Correct Forming of a Weld ......................................5-16Characteristics of a Good Weld................................5-16

Oxy-Acetylene Welding of Ferrous Metals ................5-16Steel (Including SAE 4130) .....................................5-16Chrome Molybdenum ..............................................5-17Stainless Steel ...........................................................5-17

Oxy-Acetylene Welding of Nonferrous Metals ...........5-18Aluminum Welding ..................................................5-18Magnesium Welding ...............................................5-19

Brazing and Soldering ..................................................5-20Torch Brazing of Steel .............................................5-20Torch Brazing of Aluminum ....................................5-21Soldering ..................................................................5-21

Aluminum Soldering ............................................5-21Silver Soldering ....................................................5-22

Gas Metal Arc Welding (TIG Welding) ......................5-22TIG Welding 4130 Steel Tubing ..................................... ..................................................................................5-23TIG Welding Stainless Steel ....................................5-23TIG Welding Aluminum ..........................................5-24TIG Welding Magnesium .........................................5-24TIG Welding Titanium .............................................5-24

Arc Welding Procedures, Techniques, and Welding Safety Equipment .........................................................5-25

Multiple Pass Welding .............................................5-27Techniques of Position Welding ..............................5-28Flat Position Welding ...............................................5-28

Bead Weld ............................................................5-28Groove Weld .........................................................5-28Fillet Weld ............................................................5-28Lap Joint Weld ......................................................5-29

Vertical Position Welding .......................................5-29Overhead Position Welding......................................5-29

Expansion and Contraction of Metals ..........................5-30Welded Joints Using Oxy-Acetylene Torch ................5-31

Butt Joints .................................................................5-31Tee Joints ..................................................................5-31Edge Joints ...............................................................5-31Corner Joints ............................................................5-32Lap Joints .................................................................5-32

Repair of Steel Tubing Aircraft Structure by Welding ........................................................................5-32

Dents at a Cluster Weld ............................................5-32Dents Between Clusters............................................5-32Tube Splicing with Inside Sleeve Reinforcement ....5-33Tube Splicing with Outer Split Sleeve Reinforcement ..........................................................5-34Landing Gear Repairs ...............................................5-35Engine Mount Repairs ..............................................5-36Rosette Welding .......................................................5-37

xix

Chapter 6Aircraft Wood and Structural Repair .................6-1Aircraft Wood and Structural Repair .............................6-1Wood Aircraft Construction and Repairs ......................6-2

Inspection of Wood Structures ...................................6-3External and Internal Inspection .............................6-3Glued Joint Inspection ............................................6-4Wood Condition .....................................................6-5

Repair of Wood Aircraft Structures ...............................6-7Materials .....................................................................6-7Suitable Wood ............................................................6-7

Defects Permitted ....................................................6-9Defects Not Permitted .............................................6-9Glues (Adhesives) .................................................6-10Definition of Terms Used in the Glue Process .....6-10

Preparation of Wood for Gluing ...............................6-11Preparing Glues for Use ........................................6-12Applying the Glue/Adhesive ...............................6-12Pressure on the Joint .............................................6-12Testing Glued Joints ............................................6-13

Repair of Wood Aircraft Components .....................6-13Wing Rib Repairs ................................................6-13Wing Spar Repairs ...............................................6-15Bolt and Bushing Holes ........................................6-20

Plywood Skin Repairs ..............................................6-20Fabric patch ........................................................6-20Splayed Patch ........................................................6-20Surface Patch ........................................................6-20Plug Patch .............................................................6-21Scarf Patch ............................................................6-24The Back of the Skin is Accessible for Repair ....6-25The Back of the Skin Is Not Accessible for Repair ..............................................................6-25

Chapter 7Advanced Composite Materials .........................7-1Description of Composite Structures .............................7-1

Introduction ................................................................7-1Laminated Structures ..................................................7-2

Major Components of a Laminate ..........................7-2Strength Characteristics ..........................................7-2Fiber Orientation .....................................................7-2Warp Clock .............................................................7-3

Fiber Forms ................................................................7-3Roving .....................................................................7-3Unidirectional (Tape) .............................................7-3Bidirectional (Fabric) ..............................................7-3Nonwoven (Knitted or Stitched) .............................7-4

Types of Fiber ............................................................7-4

Fiberglass ................................................................7-4

Kevlar® ...................................................................7-4Carbon/Graphite .....................................................7-6Boron ......................................................................7-6Ceramic Fibers ........................................................7-6Lightning Protection Fibers ....................................7-6

Matrix Materials .........................................................7-7Thermosetting Resins .............................................7-7

Curing Stages of Resins .............................................7-8Pre-Impregnated Products (Prepregs) ........................7-8Dry Fiber Material ......................................................7-9Thixotropic Agents .....................................................7-9Adhesives ...................................................................7-9

Film Adhesives .......................................................7-9Paste Adhesives ......................................................7-9Foaming Adhesives ..............................................7-10

Description of Sandwich Structures .............................7-10Properties ..................................................................7-11Facing Materials .......................................................7-11Core Materials ..........................................................7-11

Honeycomb ...........................................................7-11Foam .....................................................................7-12Balsa Wood ...........................................................7-13

Manufacturing and In-Service Damage .......................7-13Manufacturing Defects .............................................7-13

Fiber Breakage ......................................................7-13Matrix Imperfections ...........................................7-13Delamination and Debonds ...................................7-14Combinations of Damages ....................................7-14Flawed Fastener Holes ..........................................7-14

In-Service Defects ....................................................7-14Corrosion ..................................................................7-15

Nondestructive Inspection (NDI) of Composites ........7-15Visual Inspection ......................................................7-15Audible Sonic Testing (Coin Tapping) ...................7-16

Automated Tap Test .............................................7-16Ultrasonic Inspection ................................................7-17

Through Transmission Ultrasonic Inspection .......7-17Pulse Echo Ultrasonic Inspection .........................7-18Ultrasonic Bondtester Inspection ..........................7-18Phased Array Inspection .......................................7-18

Radiography .............................................................7-19Thermography ..........................................................7-19Neutron Radiography ...............................................7-19Moisture Detector ....................................................7-19

Composite Repairs .......................................................7-19Layup Materials ........................................................7-19

Hand Tools ............................................................7-19Air Tools ...............................................................7-20

xx

Caul Plate .............................................................7-20Support Tooling and Molds ..................................7-20

Vacuum Bag Materials ............................................7-21Release Agents ......................................................7-21Bleeder Ply ............................................................7-21Peel Ply .................................................................7-21Layup Tapes ..........................................................7-21Perforated Release Film ........................................7-21Solid Release Film ................................................7-21Breather Material ..................................................7-21Vacuum Bag ........................................................7-21

Vacuum Equipment ..................................................7-22Vacuum Compaction Table ..................................7-22

Heat Sources ............................................................7-22Oven ......................................................................7-22Autoclave ..............................................................7-23Heat Bonder and Heat Lamps ...............................7-23Thermocouples .....................................................7-25

Types of Layups .......................................................7-26Wet Layups ..........................................................7-26Prepreg ..................................................................7-27Co-curing ..............................................................7-28Secondary Bonding ...............................................7-28Co-bonding ...........................................................7-28

Layup Process (Typical Laminated Wet Layup) ......7-28Layup Techniques .................................................7-28Bleedout Technique ..............................................7-29No Bleedout ..........................................................7-29Ply Orientation Warp Clock .................................7-29

Mixing Resins .........................................................7-30Saturation Techniques ..............................................7-30

Fabric Impregnation With a Brush or Squeegee ...............................................................7-30Fabric Impregnation Using a Vacuum Bag ..........7-30

Vacuum Bagging Techniques ..................................7-31Single Side Vacuum Bagging ...............................7-31Envelope Bagging .................................................7-31

Alternate Pressure Application .................................7-32Shrink Tape ...........................................................7-32C-Clamps ..............................................................7-32Shotbags and Weights ...........................................7-32

Curing of Composite Materials ................................7-32Room Temperature Curing ...................................7-32Elevated Temperature Curing ...............................7-32

Composite Honeycomb Sandwich Repairs ..................7-33Damage Classification ..............................................7-34Sandwich Structures .................................................7-34

Minor Core Damage (Filler and Potting Repairs) .................................................................7-34

Damage Requiring Core Replacement and Repair to One or Both Faceplates .........................7-34

Solid Laminates ........................................................7-37Bonded Flush Patch Repairs .................................7-37Trailing Edge and Transition Area Patch Repairs ..................................................................7-40Resin Injection Repairs .........................................7-40Composite Patch Bonded to Aluminum Structure ................................................................7-40Fiberglass Molded Mat Repairs ............................7-41Radome Repairs ....................................................7-41External Bonded Patch Repairs ............................7-41Bolted Repairs ......................................................7-44

Fasteners Used with Composite Laminates..............7-46Corrosion Precautions ...........................................7-46Fastener Materials ................................................7-46Fastener System for Sandwich Honeycomb Structures (SPS Technologies Comp Tite) ...........7-46Hi-Lok® and Huck-Spin® Lockbolt Fasteners ....7-46Eddie-Bolt® Fasteners ..........................................7-46Cherry’s E-Z Buck® (CSR90433) Hollow Rivet ..7-47Blind Fasteners .....................................................7-47Blind Bolts ...........................................................7-48Fiberlite .................................................................7-48Screws and Nutplates in Composite Structures ....7-48

Machining Processes and Equipment .......................7-49Drilling ..................................................................7-49Countersinking ......................................................7-52Cutting Processes and Precautions .......................7-52Cutting Equipment ................................................7-52

Repair Safety ............................................................7-53Eye Protection .......................................................7-53Respiratory Protection ..........................................7-53Skin Protection ......................................................7-53Fire Protection ......................................................7-53

Transparent Plastics .....................................................7-54Optical Considerations .............................................7-54Identification .............................................................7-54

Storage and Handling ...........................................7-54Forming Procedures and Techniques .......................7-54

Heating ..................................................................7-54Forms ....................................................................7-55Forming Methods ..................................................7-55

Sawing and Drilling .................................................7-55Sawing ..................................................................7-55Drilling ..................................................................7-55

Cementing ................................................................7-56Application of Cement ..........................................7-56

xxi

Repairs ......................................................................7-56Cleaning ...................................................................7-57Polishing ...................................................................7-57Windshield Installation.............................................7-57Installation Procedures .............................................7-57

Chapter 8Aircraft Painting and Finishing ..........................8-1Introduction ...................................................................8-1Finishing Materials .......................................................8-2

Acetone .......................................................................8-2Alcohol .......................................................................8-2Benzene ......................................................................8-2Methyl Ethyl Ketone (MEK) ......................................8-2Methylene Chloride ....................................................8-2Toluene .......................................................................8-2Turpentine ..................................................................8-3Mineral Spirits ............................................................8-3Naphtha ......................................................................8-3Linseed Oil .................................................................8-3Thinners ......................................................................8-3Varnish .......................................................................8-3

Primers ...........................................................................8-3Wash Primers .............................................................8-3Red Iron Oxide ...........................................................8-3Gray Enamel Undercoat .............................................8-4Urethane ....................................................................8-4Epoxy .........................................................................8-4Zinc Chromate ............................................................8-4

Identification of Paints ...................................................8-4Dope ...........................................................................8-4Synthetic Enamel ........................................................8-4Lacquers .....................................................................8-4Polyurethane ...............................................................8-5Urethane Coating ........................................................8-5Acrylic Urethanes .......................................................8-5

Methods of Applying Finish ..........................................8-5Dipping .......................................................................8-5Brushing .....................................................................8-5Spraying .....................................................................8-5

Finishing Equipment ......................................................8-6Paint Booth .................................................................8-6Air Supply ..................................................................8-6Spray Equipment ........................................................8-6

Air Compressors .....................................................8-6Large Coating Containers .......................................8-7System Air Filters ...................................................8-7

Miscellaneous Painting Tools and Equipment ...........8-7Spray Guns ..............................................................8-7Fresh Air Breathing Systems ..................................8-8Viscosity Measuring Cup .......................................8-9

Mixing Equipment ..................................................8-9Preparation ..................................................................8-10

Surfaces ....................................................................8-10Primer and Paint .......................................................8-10

Spray Gun Operation ...................................................8-11Adjusting the Spray Pattern ......................................8-11Applying the Finish ..................................................8-11Common Spray Gun Problems .................................8-12

Sequence for Painting a Single-Engine or Light Twin Airplane ..............................................................8-13Common Paint Troubles ..............................................8-13

Poor Adhesion ..........................................................8-13Blushing ...................................................................8-13Pinholes ....................................................................8-14Sags and Runs ..........................................................8-14Orange Peel ..............................................................8-14Fisheyes ....................................................................8-15Sanding Scratches.....................................................8-15Wrinkling .................................................................8-15Spray Dust ................................................................8-16

Painting Trim and Identification Marks .......................8-16Masking and Applying the Trim ..............................8-16

Masking Materials ................................................8-16Masking for the Trim ............................................8-16

Display of Nationality and Registration Marks .......8-17Display of Marks ..................................................8-17Location and Placement of Marks ........................8-17Size Requirements for Different Aircraft .............8-18

Decals ...........................................................................8-18Paper Decals .............................................................8-18Metal Decals with Cellophane Backing ...................8-18Metal Decals With Paper Backing ...........................8-18Metal Decals with No Adhesive ...............................8-18Vinyl Film Decals ....................................................8-18Removal of Decals ..................................................8-19

Paint System Compatibility .........................................8-19Paint Touchup ..........................................................8-19

Identification of Paint Finishes .............................8-19Surface Preparation for Touchup ..........................8-20

Stripping the Finish ..................................................8-20Chemical Stripping ...............................................8-21Plastic Media Blasting (PMB) ..............................8-21New Stripping Methods ........................................8-21

Safety in the Paint Shop ...............................................8-21Storage of Finishing Materials .................................8-21

Protective Equipment for Personnel ............................8-22

xxii

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

Ohm’s Law .................................................................9-2Current ........................................................................9-2

Conventional Current Theory and Electron Theory ....................................................................9-3

Electromotive Force (Voltage) ...................................9-4Resistance ...................................................................9-4

Factors Affecting Resistance ..................................9-4Electromagnetic Generation of Power .......................9-5Alternating Current (AC) Introduction ......................9-9

Definitions ...............................................................9-9Opposition to Current Flow of AC ...........................9-12

Resistance .............................................................9-12Inductive Reactance ..............................................9-12Capacitive Reactance ............................................9-14Impedance ............................................................9-15Parallel AC Circuits ..............................................9-18Power in AC Circuits ............................................9-20True Power ............................................................9-20Apparent Power ...................................................9-20

Power Factor ............................................................9-20Aircraft Batteries ..........................................................9-21

Type of Batteries ......................................................9-21Lead-Acid Batteries ..............................................9-21NiCd Batteries ......................................................9-22Capacity ................................................................9-22Aircraft Battery Ratings by Specification .............9-23Storing and Servicing Facilities ............................9-23Battery Freezing ....................................................9-23Temperature Correction ........................................9-23Battery Charging ..................................................9-24Battery Maintenance .............................................9-24Battery and Charger Characteristics .....................9-25Aircraft Battery Inspection ...................................9-26Ventilation Systems ..............................................9-26Installation Practices .............................................9-26Troubleshooting ....................................................9-27

DC Generators and Controls ....................................9-27Generators .............................................................9-27Construction Features of DC Generators ..............9-29Types of DC Generators .......................................9-32Generator Ratings .................................................9-33DC Generator Maintenance ..................................9-33

Generator Controls ...................................................9-34Theory of Generator Control ................................9-34Functions of Generator Control Systems ..............9-35

Generator Controls for High Output Generators .............................................................9-35Generator Controls for Low-Output Generators .............................................................9-36

DC Alternators and Controls ....................................9-38DC Alternators .....................................................9-39Alternator Voltage Regulators .............................9-40Solid-State Regulators ..........................................9-40

Power Systems .........................................................9-41AC Alternators ........................................................9-41Alternator Drive ......................................................9-42AC Alternators Control Systems .............................9-45

Aircraft Electrical Systems ..........................................9-47Small Single-Engine Aircraft ...................................9-47

Battery Circuit ......................................................9-47Generator Circuit ..................................................9-48Alternator Circuit ..................................................9-48External Power Circuit .........................................9-50Starter Circuit ........................................................9-50Avionics Power Circuit .........................................9-51Landing Gear Circuit ............................................9-52AC Supply ............................................................9-55

Light Multiengine Aircraft .......................................9-57Paralleling Alternators or Generators ...................9-57Power Distribution on Multiengine Aircraft ........9-58

Large Multiengine Aircraft ......................................9-60AC Power Systems ...............................................9-60

Wiring Installation .......................................................9-65Wiring Diagrams .....................................................9-65

Block Diagrams ....................................................9-65Pictorial Diagrams ................................................9-65Schematic Diagrams .............................................9-65

Wire Types ...............................................................9-65Conductor .............................................................9-67Plating ...................................................................9-68Insulation ..............................................................9-68Wire Shielding ......................................................9-68Wire Substitutions ................................................9-69Areas Designated as Severe Wind and Moisture Problem (SWAMP) ..............................9-69

Wire Size Selection ..................................................9-69Current Carrying Capacity ....................................9-71Allowable Voltage Drop .......................................9-75

Wire Identification ....................................................9-77Placement of Identification Markings ...................9-77Types of Wire Markings ......................................9-77

Wire Installation and Routing ..................................9-78Open Wiring .........................................................9-78

xxiii

Wire Groups and Bundles and Routing ................9-78Conduit .................................................................9-83Wire Shielding ......................................................9-85

Lacing and Tying Wire Bundles ..............................9-88Tying .....................................................................9-89

Wire Termination .....................................................9-90Stripping Wire .....................................................9-90Terminal Strips .....................................................9-91Terminal Lugs .......................................................9-91Emergency Splicing Repairs .................................9-92

Junction Boxes .....................................................9-92AN/MS Connectors ..............................................9-93Coaxial Cable ........................................................9-96

Wire Inspection ........................................................9-96Electrical System Components ....................................9-96

Switches ...................................................................9-96Type of Switches ..................................................9-98Toggle and Rocker Switches ................................9-98Rotary Switches ....................................................9-99Precision (Micro) Switches ...................................9-99

Relays and Solenoids (Electromagnetic Switches) ..................................................................9-99

Solenoids ...............................................................9-99Relays ...................................................................9-99

Current Limiting Devices .......................................9-100Fuses ...................................................................9-100Circuit Breakers ..................................................9-100

Aircraft Lighting Systems ..........................................9-101Exterior Lights ........................................................9-101

Position Lights ....................................................9-101Anticollision Lights ............................................9-102Landing and Taxi Lights .....................................9-103Wing Inspection Lights .......................................9-104

Interior Lights .........................................................9-104Maintenance and Inspection of Lighting Systems ...................................................................9-105

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

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

1-2

Figure 1-1. George Cayley, the father of aeronautics (top) and a flying replica of his 1853 glider (bottom).

Figure 1-2. Master of gliding and wing study, Otto Lilienthal (top) and one of his more than 2,000 glider flights (bottom).

Earlier, Cayley studied the center of gravity of flying machines, as well as the effects of wing dihedral. Furthermore, he pioneered directional control of aircraft by including the earliest form of a rudder on his gliders. [Figure 1-1]

In the late 1800s, Otto Lilienthal built upon Cayley’s discoveries. He manufactured and flew his own gliders on over 2,000 flights. His willow and cloth aircraft had wings designed from extensive study of the wings of birds. Lilienthal also made standard use of vertical and horizontal fins behind the wings and pilot station. Above all, Lilienthal proved that man could fly. [Figure 1-2]

Octave Chanute, a retired railroad and bridge engineer, was active in aviation during the 1890s. [Figure 1-3] His interest was so great that, among other things, he published a definitive work called “Progress in Flying Machines.” This was the culmination of his effort to gather and study all the

information available on aviation. With the assistance of others, he built gliders similar to Lilienthal’s and then his own. In addition to his publication, Chanute advanced aircraft structure development by building a glider with stacked wings incorporating the use of wires as wing supports.

The work of all of these men was known to the Wright Brothers when they built their successful, powered airplane in 1903. The first of its kind to carry a man aloft, the Wright Flyer had thin, cloth-covered wings attached to what was primarily truss structures made of wood. The wings contained forward and rear spars and were supported with both struts and wires. Stacked wings (two sets) were also part of the Wright Flyer. [Figure 1-4]

1-3

Figure 1-3. Octave Chanute gathered and published all of the aeronautical knowledge known to date in the late 1890s. Many early aviators benefited from this knowledge.

Figure 1-4. The Wright Flyer was the first successful powered aircraft. It was made primarily of wood and fabric.

Figure 1-5. The world’s first mono-wing by Louis Bleriot.

Powered heavier-than-air aviation grew from the Wright design. Inventors and fledgling aviators began building their own aircraft. Early on, many were similar to that constructed by the Wrights using wood and fabric with wires and struts to support the wing structure. In 1909, Frenchman Louis Bleriot produced an aircraft with notable design differences. He built a successful mono-wing aircraft. The wings were

still supported by wires, but a mast extending above the fuselage enabled the wings to be supported from above, as well as underneath. This made possible the extended wing length needed to lift an aircraft with a single set of wings. Bleriot used a Pratt truss-type fuselage frame. [Figure 1-5]

More powerful engines were developed and airframe structures changed to take advantage of the benefits. As early as 1910, German Hugo Junkers was able to build an aircraft with metal truss construction and metal skin due to the availability of stronger powerplants to thrust the plane forward and into the sky. The use of metal instead of wood for the primary structure eliminated the need for external wing braces and wires. His J-1 also had a single set of wings (a monoplane) instead of a stacked set. [Figure 1-6]

1-4

Figure 1-6. The Junker J-1 all metal construction in 1910.

Figure 1-7. World War I aircraft were typically stacked-wing fabric-covered aircraft like this Breguet 14 (circa 1917).

Figure 1-8. The flying boat hull was an early semimonocoque design like this Curtiss HS-2L.

Leading up to World War I (WWI), stronger engines also allowed designers to develop thicker wings with stronger spars. Wire wing bracing was no longer needed. Flatter, lower wing surfaces on high-camber wings created more lift. WWI expanded the need for large quantities of reliable aircraft. Used mostly for reconnaissance, stacked-wing tail draggers with wood and metal truss frames with mostly fabric skin dominated the wartime sky. [Figure 1-7] The Red Baron’s Fokker DR-1 was typical.

In the 1920s, the use of metal in aircraft construction increased. Fuselages able to carry cargo and passengers were developed. The early flying boats with their hull-type construction from the shipbuilding industry provided the blueprints for semimonocoque construction of fuselages. [Figure 1-8] Truss-type designs faded. A tendency toward cleaner monowing designs prevailed.

Into the 1930s, all-metal aircraft accompanied new lighter and more powerful engines. Larger semimonocoque fuselages were complimented with stress-skin wing designs. Fewer truss and fabric aircraft were built. World War II (WWII) brought about a myriad of aircraft designs using all metal technology. Deep fuel-carrying wings were the norm, but the desire for higher flight speeds prompted the development of thin-winged aircraft in which fuel was carried in the fuselage. The first composite structure aircraft, the De Havilland Mosquito, used a balsa wood sandwich material in the

construction of the fuselage. [Figure 1-9] The fiberglass radome was also developed during this period.

After WWII, the development of turbine engines led to higher altitude flight. The need for pressurized aircraft pervaded aviation. Semimonocoque construction needed to be made even stronger as a result. Refinements to the all-metal semimonocoque fuselage structure were made to increase strength and combat metal fatigue caused by the pressurization-depressurization cycle. Rounded windows and door openings were developed to avoid weak areas where cracks could form. Integrally machined copper alloy aluminum skin resisted cracking and allowed thicker skin and controlled tapering. Chemical milling of wing skin structures provided great strength and smooth high performance surfaces. Variable contour wings became easier