Contents Paragraph Page
Page vi
1-44..............................................SPAR LONGITUDINAL CRACKS AND LOCAL DAMAGE
.1-16
FIGURE 1-10..METHOD OF REIN FORCING A LONGITUDINAL CRACK
AND/OR LOCAL DAMAGE IN A SOLID SPAR1-22
1-45.................................................................................... ELONGATED HOLES IN SPARS
.1-18
1-46...................................................................................................................RIB REPAIRS
.1-18
FIGURE 1- 11..................................................... REPAIR OF WOOD RIBS 1-23 FIGURE 1-12.................T YPICAL WING COMPRESSION RIB REPAIRS 1-24
1-47............................................................................................... PLYWOOD SKIN REPAIR
.1-20
1-48......................................... DETERMINATION OF SINGLE OR DOUBLE CURVATURE
.1-20
1-49.................................................REPAIRS TO SINGLE CURVATURE PLYWOOD SKIN
.1-20
TABLE 1-2.MINIMUM RECOMME NDED BEND RADII FOR AIRCRAFT PLYWOOD 1-25
1-50............................................... REPAIRS TO DOUBLE CURVATURE PLYWOOD SKIN
.1-22
1-51......................................................................................................TYPES OF PATCHES
.1-25
FIGURE 1-13. ................................................................SPLAYED PATCH 1-27 FIGURE 1-14........................................................... SURFACE PATCHES 1-28 FIGURE 1-15............SCARF PATCH ES (BACK OF SKIN ACCESSIBLE) 1-29 FIGURE 1-16... SCARF PATCHES (BACK OF SKIN NOT ACCESSIBLE) 1-30 FIGURE 1-17. ....................................... OVAL PLUG PATCH ASSEMBLY 1-32 FIGURE 1- 18.....................................ROUND PLUG PATCH ASSEMBLY 1-33
1-52...............................................................................................................FABRIC PATCH
.1-31
1-53.1-63. [RESERVED.]1-33
SECTION 5. FINISHING WOOD STRUCTURES
1-64GENERAL
.1-35
1-65................................................................................................ ACCEPTABLE FINISHES
.1-35
1-66PRECAUTIONS
.1-35
1-67..........................................................................FINISHING OF INTERIOR SURFACES
.1-36
1-68.........................................................................FINISHING OF EXTERIOR SURFACES
.1-36
1-69.......................................................................FINISHING OF END GRAIN SURFACES
.1-36
Contents Paragraph Page
Page vii
1-70..............................................................................FINISHING WITH FABRIC OR TAPE
.1-37
1-71............................................................................................ SEALING OF BOLT HOLES
.1-37
1-72.1-79. [RESERVED.]1-37
CHAPTER 2. FABRIC COVERING SECTION 1. PRACTICES AND PRECAUTIONS
2-1GENERAL
.2-1
2-2.............................................................................................................PROBLEM AREAS
.2-1
2-3..................................................................................... AIRCRAFT FABRIC-SYNTHETIC
.2-1
2-4......................................................................................... AIRCRAFT FABRIC-NATURAL
.2-2
TABLE 2-1. ................................................ COTTON AND LINEN FABRICS 2-3
2-5................................................................................................ RECOVERING AIRCRAFT
.2-2
TABLE 2-2. ........................ CO TTON AND LINEN, TAPES AND THREADS 2-4
2-6...............................................PREPARATION OF THE STRUCTURE FOR COVERING
.2-2
2-7.................................................................................................................FABRIC SEAMS
.2-5
FIGURE 2-1. ........................................................................FABRIC SEAMS 2-7 FIGURE 2-2....................... T YPICAL METHODS OF ATTACHING FABRIC 2-8
2-8..................................................................................................... COVERING METHODS
.2-9
Contents (continued) Paragraph Page
Page viii
2-9........................................................................................................REINFORCING TAPE
.2-10
FIGURE 2- 3............................................ EXPLODED SIDE VIEW OF RIB 2-10
2-10............................................................................................................................L A C I N G
.2-11
FIGURE 2-4.STANDARD EXTERNAL MO DIFIED SEINE KNOT USED FOR
SINGLE AND DOUBLE RIB LACING2-11
FIGURE 2- 5.................................. STARTING STITCH FOR RIB LACING 2-12 FIGURE 2-6. ....................................STANDARD SINGLE-LOOP LACING 2-13 FIGURE 2-7............... ST ANDARD KNOT FOR DOUBLE-LOOP LACING 2-14 FIGURE 2-8............. ST ANDARD DOUBLE-LOOP LACING (OPTIONAL) 2-15 FIGURE 2-9A.ALTERNATE SEQUENCE TO TIE A MODIFIED SEINE KNOT
FOR RIB LACING2-16
FIGURE 2-9B.ALTERNATE SEQUENCE TO TIE A MODIFIED SEINE KNOT
FOR RIB LACING2-17
FIGURE 2-9C.ALTERNATE SEQUENCE TO TIE A MODIFIED SEINE KNOT
FOR RIB LACING2-18
FIGURE 2-10. ......................................................................SPLICE KNOT 2-19 FIGURE 2-11.BLINDSTITCH LACING - SQUARE KNOT SECURED WITH HALF HITCHES 2-20
2-11........................................................................................................... STITCH SPACING
.2-19
FIGURE 2-12. ..................................... FABRIC ATTACHMENT SPACING 2-21
2-12FASTENERS
.2-21
2-13.............................................................................................................FINISHING TAPE
.2-22
2-14............................................................INSPECTION RINGS AND DRAIN GROMMETS
.2-22
2-15.2-19. [RESERVED.]2-23
SECTION 2. APPLICATION OF DOPE
2-20GENERAL
.2-25
TABLE 2-3............................................SAFET Y TIPS FOR DOPE/PAINT 2-26 TABLE 2-4................................................................... TIPS FOR DOPING 2-26
2-21......................................... DOPE APPLICATION PROCEDURE (NATURAL FABRICS)
.2-26
2-22........................................................................................COVERING OVER PLYWOOD
.2-28
2-23..............................................................................COATING APPLICATION DEFECTS
.2-29
2-24.2-29. [RESERVED.]2-31
SECTION 3. INSPECTION AND TESTING
Contents (continued) Paragraph Page
Page ix
2-30GENERAL
.2-33
2-31...............................................................................................FABRIC IDENTIFICATION
.2-34
2-32...........................................................................................COATING IDENTIFICATION
.2-34
2-33..........................................................STRENGTH CRITERIA FOR AIRCRAFT FABRIC
.2-35
2-34............................................................................................................FABRIC TESTING
.2-35
2-35................................................................................... REJUVENATION OF DOPE FILM
.2-36
2-36.2-41. [RESERVED.]2-36
SECTION 4. REPAIRS TO FABRIC COVERING
2-42GENERAL
.2-37
2-43............................................................ REPAIR OF TEARS AND ACCESS OPENINGS
.2-37
FIGURE 2-13 ........................................... REPAIR OF TEARS IN FABRIC 2-38
2-44...................................................................................................SEWN-PATCH REPAIR
.2-38
FIGURE 2- 14........................................................ HAND-STITCH DETAIL 2-39
2-45..........................................................................................DOPED-ON PATCH REPAIR
.2-39
2-46.2-51. [RESERVED.]2-40
Contents (continued) Paragraph Page
Page x Chapter 3. Fiberglass And Plastics SECTION 1. REPAIR OF LIGHT LOAD LAMINATE STRUCTURES
3-1GENERAL
.3-1
3-2.................................................................................FIBERGLASS LAMINATE REPAIRS
.3-1
FIGURE 3-1. ..............................TYPICAL LAMINATE (FACING) REPAIR 3-2 FIGURE 3- 2................................ TYPICAL CORE AND FACING REPAIR 3-2 FIGURE 3-3. .....................................TYPICAL STEPPED JOINT REPAIR 3-3
3-3..........................................................................................................REPAIRING HOLES
.3-3
FIGURE 3-4....................... PREPARING THE FIBERGLASS SANDWICH 3-3 FIGURE 3-5.SCARFED REPAIR TO A NONSTRUCTURAL LAMINATED
FIBERGLASS COMPONENT3-4
FIGURE 3-6.BALANCED LAYUP SAME AS ORIGINAL NUMBER OF PLIES,
PLUS ONE EXTRA PLY3-4
FIGURE 3-7. ......................................... TYPICAL SCARF JOINT REPAIR 3-5 FIGURE 3-8.CAREFULLY CUT THROUGH EACH LAYER OF FIBERGLASS
CLOTH AND ...............................................REMOVE IT FROM THE DAMAGED AREA 3-5
3-4................................................................ SAMPLE BAGGING AND CURING PROCESS
.3-5
FIGURE 3-9.................... SAMPLE BA GGING LAYUP CROSS SECTION 3-6
3-5.3-9. [RESERVED.]3-8
SECTION 2. METALLIC SANDWICH SECONDARY STRUCTURE REPAIRS
3-10.............................REPAIRS TO METALLIC SANDWICH SECONDARY STRUCTURE
.3-9
FIGURE 3-10.....................T YPICAL TYPES OF CORE REPLACEMENT 3-10 FIGURE 3-11............. T YPICAL UNDERCUT CORE MATERIAL CAVITY 3-10 FIGURE 3-12.CROSS SECTION OF BONDED AND BOLTED OVERLAP REPAIRS 3-11 FIGURE 3-13. ........................................HONEYCOMB CORE REMOVAL 3-11 FIGURE 3-14..... REMOVING HON EYCOMB CORE FROM A TAPERED
CONTROL SURFACE3-11
FIGURE 3-15. .........................REMOVAL OF CORE WITH CORE KNIFE 3-11 FIGURE 3-16. ...............................................DETAILS OF CORE REPAIR 3-12
3-11FINISHING
.3-12
3-12.3-17. [RESERVED.]3-13
SECTION 3. TRANSPARENT PLASTICS
Contents (continued) Paragraph Page
Page xi
3-18GENERAL
.3-15
3-19............................................................................................STORAGE AND HANDLING
.3-15
3-20............................................................ FORMING PROCEDURES AND TECHNIQUES
.3-15
3-21.........................................................................................................................HEATING.
.3-16
FIGURE 3-17. ...................................... HANGING OF ACRYLIC SHEETS 3-16
3-22FORMS
.3-16
3-23..................................................................................................... FORMING METHODS
.3-17
TABLE 3-1.TYPICAL TEMPERATURES FOR FORMING ACRYLIC SHEETS 3-17 FIGURE 3-18.DRILL HAVING AN INCLUDED ANGLE OF APPROXIMATELY 150°, ...................................................... USED TO DRILL ACRYLIC PLASTICS 3-18 FIGURE 3-19..........UNIBIT DRILL FO R DRILLING ACRYLIC PLASTICS 3-18 FIGURE 3-20.............. APPLYING PR ESSURE TO ACRYLIC PLASTICS 3-19
Contents (continued) Paragraph Page
Page xii
3-24....................................................................................................REPAIR OF PLASTICS
.3-19
FIGURE 3- 21...................................................STOP-DRILLING CRACKS 3-20 FIGURE 3-22........................................................... SURFACE PATCHES 3-20 FIGURE 3- 23......................................................... PLUG PATCH REPAIR 3-21
3-25..............................................CLEANING AND POLISHING TRANSPARENT PLASTIC
.3-21
3-26............................................................................................... REPLACEMENT PANELS
.3-21
3-27..................................................................................... INSTALLATION PROCEDURES
.3-22
3-28.3-39. [RESERVED.]3-22
SECTION 4. WINDSHIELDS, ENCLOSURES, AND WINDOWS
3-40GENERAL
.3-23
FIGURE 3-24.TEMPORARY REPAIRS TO CRACKED WINDSHIELDS OR WINDOWS 3-24
3-41PROTECTION
.3-24
3-42........................................................................................WINDSHIELD INSTALLATION
.3-24
3-43.3-47. [RESERVED.]3-25
Chapter 4. Metal Structure, Welding, And Brazing SECTION 1. IDENTIFICATION OF METALS
4-1GENERAL
.4-1
TABLE 4-1.................................. FE RROUS (IRON) ALLOY MATERIALS 4-1
4-2...............................................................................IDENTIFICATION OF STEEL STOCK
.4-1
TABLE 4-2.......... NUMERICAL SYSTEM FOR STEEL IDENTIFICATION 4-2 TABLE 4-3.EXAMPLES OF STAINL ESS AND HEAT-RESISTANT STEELS
NOMINAL COMPOSITION (PERCENT)4-2
4-3...................................................................INTERCHANGEABILITY OF STEEL TUBING
.4-2
4-4.................................................................................... IDENTIFICATION OF ALUMINUM
.4-2
TABLE 4-4.BASIC TEMPER DESIGNAT IONS AND SUBDIVISIONS FROM
ALUMINUM ALLOYS4-3
4-5.4-15. [RESERVED.]4-3
SECTION 2. TESTING OF METALS
4-16.....................................................................................................HARDNESS TESTING
.4-5
4-17......................................................................................ROCKWELL HARDNESS TEST
.4-5
4-18........................................................................................... BRINELL HARDNESS TEST
.4-5
Contents (continued) Paragraph Page
Page xiii
4-19.......................................................................................... VICKERS HARDNESS TEST
.4-6
4-20.........................................................................................MICROHARDNESS TESTING
.4-6
4-21INDENTIONS
.4-7
FIGURE 4-1.COMPARISON OF INDENTATION MADE BY KNOOP AND
VICKERS INDENTERS ..................... IN THE SAME WORK META L AND AT THE SAME LOADS 4-7
4-22......................................................................................................MAGNETIC TESTING
.4-8
4-23......................................................................................................ALUMINUM TESTING
.4-8
TABLE 4-5.HARDNESS VALUES FOR ALUMINUM ALLOYS. (REFERENCE MIL-H-6088G.) 4-8
4-24.4-35. [RESERVED.]4-8
Contents (continued) Paragraph Page
Page xiv SECTION 3. PRECAUTIONARY MEASURES
4-36.................................................................FLUTTER AND VIBRATION PRECAUTIONS
.4-9
4-37....................................................................................LOAD FACTORS FOR REPAIRS
.4-10
4-38................................................... TRANSFER OF STRESSES WITHIN A STRUCTURE
.4-10
4-39.4-49. [RESERVED.]4-10
SECTION 4. METAL REPAIR PROCEDURES
4-50GENERAL
.4-11
4-51................................... RIVETED (OR BOLTED) STEEL TRUSS-TYPE STRUCTURES
.4-11
4-52................................................................................ALUMINUM ALLOY STRUCTURES
.4-11
4-53.........................................SELECTION OF ALUMINUM FOR REPLACEMENT PARTS
.4-12
4-54.....................................................HEAT TREATMENT OF ALUMINUM ALLOY PARTS
.4-12
4-55............................................................................................................ BENDING METAL
.4-13
TABLE 4-6.RECOMMENDED RADII FO R 90-DEGREE BENDS IN ALUMINUM ALLOYS 4-14
4-56SETBACK
.4-13
FIGURE 4-2. .................................. SETBACK FOR A 90-DEGREE BEND 4-13 TABLE 4-7.K-CHART FOR DETERMINING SETBACK FOR BENDS OTHER
THAN 90 DEGREES4-15
FIGURE 4-3.METHODS OF DETERMINING SETBACKS FOR BENDS OTHER
THAN 90 DEGREES4-16
4-57RIVETING
.4-14
FIGURE 4-4.RIVET IDENTIFICA TION AND PART NUMBER BREAKDOWN 4-16 TABLE 4-8....................................... AIRCRAFT RIVET IDENTIFICATION 4-17 FIGURE 4-5.RIVET HOLE SPACING A ND EDGE DISTANCE FOR SINGLE-LAP
SHEET SPLICES4-20
FIGURE 4-6......... RIVETING PRACTICE AND RIVET IMPERFECTIONS 4-21 FIGURE 4-7........SELF PLUGGING FRICTION-LOCK CHERRY RIVETS 4-22 FIGURE 4-8.MECHANICAL-LOCK (BULBED CHERRY) CHERRY RIVET 4-23 FIGURE 4-9.............................................................CHERRY MAX RIVET 4-24 FIGURE 4- 10.............................................................OLYMIC-LOK RIVET 4-25 FIGURE 4- 11.........................................................................HUCK RIVET 4-26
Contents (continued) Paragraph Page
Page xv
4-58.................REPAIR METHODS AND PRECAUTIONS FOR ALUMINUM STRUCTURE
.4-25
FIGURE 4-12.TYPICAL REPAIR ME THOD FOR TUBULAR MEMBERS OF
ALUMINUM ALLOY4-28
FIGURE 4-13.TYPICAL REPAIR FOR BUCKLED OR CRACKED METAL WING RIB CAPSTRIPS 4-29 FIGURE 4-14.TYPICAL METAL RIB REPAIRS (USUALLY FOUND ON SMALL
AND MEDIUM-SIZE AIRCRAFT)4-30
FIGURE 4-15. ........................ TYPICAL REPAIRS OF TRAILING EDGES 4-31 FIGURE 4-16.TYPICAL REPAIRS OF STRESSED SHEET METAL COVERINGS 4-32 FIGURE 4-17................... TYPICAL ST RINGER AND FLANGE SPLICES 4-33 FIGURE 4-18.EXAMPLE OF STRING ER SPLICE (MATERIAL-2017 ALLOY) 4-34 FIGURE 4-19........ APPLICATION OF TYPICAL FLANGE SPLICES AND
REINFORCEMENT4-35
TABLE 4-9.NUMBER OF RIVETS REQU IRED FOR SPLICES (SINGLE-LAP JOINT) IN BARE 2014-T6, 2024-T3, 2024-T3, A ND 7075-T6 SHEET, CLAD 2014-T6, 2024-T3, 2024-T36, AND 7075-T6 SHEET, 2024-T4, AND 7075-T6 PLATE, ............. BAR, ROD, TUBE, AND EXTRUSIONS, 2014-T6 EXTRUSIONS 4-37 TABLE 4-10.NUMBER OF RIVETS RE QUIRED FOR SPLICES (SINGLE-LAP JOINT) . IN 2017, 1017 ALCLAD, 2024-T3 ALCL AD SHEET, PLATE, BAR, ROD, .........................................................................TUBE, A ND EXTRUSIONS 4-38 TABLE 4-11.NUMBER OF RIVETS RE QUIRED FOR SPLICES (SINGLE-LAP JOINT) ....................................................... IN 5032 (ALL HARDNESSES) SHEET 4-39
Contents (continued) Paragraph Page
Page xvi
4-59................................................................................REPAIRING CRACKED MEMBERS
.4-40
FIGURE 4-20.EXAMPLE OF INTERM EDIATE FRAME STRINGER SPLICE
(MATERIAL 2017-T3 AL ALLOY)4-41
FIGURE 4-21.TYPICAL METHODS OF REPAIRING CRACKED LEADING AND
TRAILING EDGES
AND RIB INTER SECTIONS4-42
FIGURE 4-22.TYPICAL METHODS OF REPLACING CRACKED MEMBER AT FITTINGS 4-43 FIGURE 4-23.TYPICAL METHODS OF REPAIRING CRACKED FRAME AND
STIFFENER COMBINATION4-44
FIGURE 4-24.TYPICAL REPAIRS TO RUDDER AND TO FUSELAGE AT TAIL POST 4-45
4-60................................................................................STEEL AND ALUMINUM FITTINGS
.4-40
FIGURE 4-25.TYPICAL METHODS OF REPAIRING ELONGATED OR WORN BOLT HOLES 4-46
4-61CASTINGS
.4-40
4-62.................................................. SELECTIVE PLATING IN AIRCRAFT MAINTENANCE
.4-40
4-63.4-73. [RESERVED.]4-51
SECTION 5. WELDING AND BRAZING
4-74GENERAL
.4-53
TABLE 4-12.CURRENT AND POLARITY SELECTION FOR INERT GAS WELDING 4-54 FIGURE 4-26.COMMON DEFECTS TO AVOID WHEN FITTING AND WELDING
AIRCRAFT CERTIFICATION CLUSTER4-55
TABLE 4-13.................................................................. TORCH TIP SIZES 4-55 FIGURE 4-27................. BU TT-WELDING STRENGTH CALCULATIONS 4-56
4-75......................................................................................................TYPES OF WELDING
.4-56
FIGURE 4-28.BASIC GAS-WELDING FLAMES: EACH HAS DISTINCTIVE SHAPE, COLOR AND SOUND.
................................................... NEUT RAL FLAME IS THE MOST USED 4-57 FIGURE 4-29.SET TIG WELDER TO DC CURRENT, STRAIGHT POLARITY
FOR WELDING MILD STEEL, ..........................................................STAINLESS STEEL AND TITANIUM 4-57 FIGURE 4-30.SET TIG TO AC CURRE NT FOR WELDING ALUMINUM AND MAGNESIUM 4-58
4-76............................................................................. ELECTRIC-RESISTANCE WELDING
.4-58
FIGURE 4-31.IN SPOT WELDING, HEAT IS PRODUCED BY ELECTRICAL
RESISTANCE BETWEEN COPPER ELECTRODES. PRESSURE IS SIMULTANEOUSLY APPLIED TO
ELECTRODE TIPS TO FORCE METAL TOGETHER TO COMPLETE FUSING PROCESS. SPOT-
WELD-NUGGET SIZE
Contents (continued) Paragraph Page
Page xvii .......................................................IS DIRECT LY RELATED TO TIP SIZE 4-58
4-77BRAZING
.4-58
TABLE 4-14.CALCULATED ALLO WABLE STRENGTH OF BASE METAL 4-59 FIGURE 4-32. ..................................................SILVER BRAZING JOINTS 4-60 FIGURE 4-33. ........................................... ELECTRIC SOLDERING IRON 4-61
4-78..................................................................... AIRCRAFT PARTS NOT TO BE WELDED
.4-61
4-79..........................................................................................WELDING ROD SELECTION
.4-62
TABLE 4-15....CHART SHOWING WELDING FILLER ROD SELECTION 4-62
4-80.................................................................................REPAIR OF TUBULAR MEMBERS
.4-62
FIGURE 4-34.FINGER PATCH REPAIRS FOR MEMBERS DENTED AT A CLUSTER 4-63
4-81.......................................................................................REPAIR BY WELDED SLEEVE
.4-64
FIGURE 4-35.MEMBERS DENTED IN A BAY (REPAIRS BY WELDED SLEEVE) 4-65
4-82........................................................................................REPAIR BY BOLTED SLEEVE
.4-64
4-83..............................................................................................WELDED-PATCH REPAIR
.4-64
FIGURE 4- 36. ................................................. WELDED PATCH REPAIR 4-66
4-84........................................................SPLICING TUBING BY INNER-SLEEVE METHOD
.4-64
FIGURE 4-37. ...........................SPLICING BY INNER-SLEEVE METHOD 4-67
4-85...................................................... SPLICING TUBING BY OUTER-SLEEVE METHOD
.4-66
FIGURE 4-38.SPLICING BY OUTE R-SLEEVE METHOD (REPLACEMENT BY
WELDED OUTSIDE SLEEVE)4-68