Repair Manual: Trainer Airplanes

58 REPAIR WOOD MOISTURE CONTROL .... 73 59 SUBSTITUTES FOR SPECIFIED WOODS ... 74 60 CASEIN GLUE FOR WOOD REPAIRS .... 75 61 MIXING CASEIN GLUE FOR WOOD REPAIRS . 75 62 ASSEMBLING GLUED JOINTS OF WOOD ... 75 63 APPLICATION OF WOOD-GLUING PRESSURE WITH CLAMPS 76 64 APPLICATION OF WOOD-GLUING PRESSURE WITH NAI LING STRIPS 76 65 WOODEN REAR FUSELAGE STRINGERS ... 77 66 WOODEN REAR FUSELAGE BAGGAGE COMPART- MENT INTERCOSTAL 79 67 WOODEN REAR FUSELAGE UPPER LONGERONS 80 68 WOODEN REAR FUSELAGE LOWER LONGERONS 82 69 FLUSH PATCH FOR PLYWOOD SKIN HOLES LESS THAN 2 INCHES WIDE 84 70 EXTERNAL PATCH FOR PLYWOOD SKIN HOLES LESS THAN 2 INCHES WIDE 84 71 REPLACING DAMAGED PLYWOOD SKIN SECTION 72 BULKHEAD PLYWOOD WEBS 73 WOODEN REAR FUSELAGE FORMERS .... 74 GENERAL FINISH REQUIREMENTS FOR WOOD 75 WOOD FINISH MATERIALS 76 WOOD REPAIR MATERIALS 77 WOOD REPAIR TOOLS 85 86 86 90 SECTION 3 FIXED SURFACES 1 WING CONSTRUCTION 91 2 HORIZONTAL STABILIZER CONSTRUCTION . 91 3 VERTICAL STABILIZER CONSTRUCTION . . 91 4 STRINGERS - GENERAL 97 5 STRINGER REPAIRS - GENERAL 97 6 STRINGER TYPE C107LT-20 99 7 STRINGER TYPE CI23LT 100 8 STRINGER TYPE C148T 101 9 DOUBLED C148T TYPE STRINGERS .... 102 10 STRINGER TYPE C180T 104 11 STRINGER TYPE C204T 104 12 DOUBLED C204T TYPE STRINGERS .... 105 13 STRINGER TYPE C250T 105 14 DOUBLED C250T TYPE STRINGERS .... 106 15 COMBINATION C250T~C366T STRINGERS . . 107 16 STRINGER TYPE C265T 108 17 STRINGER TYPE C266T 109 18 STRINGER TYPE C274T 109 19 STRINGER TYPE C366T 110 20 DOUBLED C366T TYPE STRINGERS .... Ill 21 STRINGER TYPE C3731-T Ill 22 STRINGER TYPE K77A 112 23 DOUBLED STRINGER TYPES K77A 112 24 WING TRAILING EDGE II3 25 SPAR REPAIRS - GENERAL II3 26 OUTER WING MAIN SPAR - ROOT TO 106 INCHES OUTBOARD 114 27 OUTER WING MAIN SPAR - 106 TO 151 INCHES OUTBOARD OF ROOT 114 28 OUTER WING MAIN SPAR - 151 INCHES OUTBOARD TO TIP 116 29 OUTER WING FLAP SPAR 119 30 OUTER WING AILERON SPAR 119 31 CENTERSECTION FLAP SPAR 119 32 CENTERSECTION REAR SPAR 122 33 CENTERSECTION FRONT SPAR UPPER CAP . 124 34 CENTERSECTION FRONT SPAR LOWER CAP . 126 35 PATCHING CENTERSECTION FRONT SPAR WEB 128 36 SPLICING CENTERSECTION FRONT SPAR WEB 13O 37 VERTICAL STABILIZER FRONT SPAR ... 13O 38 VERTICAL STABILIZER REAR SPAR AREA ABOVE ROOT RIB I3O 39 VERTICAL STABILIZER REAR SPAR AREA BELOW ROOT RIB 132 RESTRICTED [ii] RESTRICTED CONTENTS Par. Page 40 REPAIR OF WOODEN HORIZONTAL STABILIZER 132 41 HORIZONTAL STABILIZER FRONT SPAR ... I32 42 HORIZONTAL STABILIZER REAR SPAR AREA OUTBOARD OF CENTER HINGE FITTING . . I35 43 HORIZONTAL STABILIZER REAR SPAR AREA INBOARD OF CENTER HINGE FITTING- . • 136 44 SKIN - GENERAL I36 45 SMALL HOLES IN SKIN LESS THAN 1/2- fNCH DIAMETER I37 46 SMALL HOLES IN SKIN 1/2- TO 1-INCH DIAMETER I37 47 ISOLATED SKIN CRACKS 138 48 PREPARING LARGE HOLES IN SKIN FOR PATCHING 138 49 PATCHING LARGE HOLES IN SKIN I39 50 LOCATING BLIND RIVET HOLES IN SKIN . . 140 51 SPLICING SKIN PANELS 141 52 PREPARING WING LEADING EDGE SKIN FOR SPLICING 143 53 SPLICING WING LEADING EDGE SKIN. ... 145 54 REMOVING AND REPLACING THE OUTER WING CLOSING STRIP SKIN 147 55 REMOVING AND REPLACING SKIN PANELS • . 148 56 REMOVING DENTS IN THE HORIZONTAL STABI- LIZER TIP SKIN 149 57 FUEL TANK COMPARTMENT COVER FORMERS- - 149 58 CENTERSECTION INTERMEDIATE RIBS- - - . 150 59 WING TRAILING EDGE RIBS AND CENTER- SECTION LEADING EDGE RIBS 151 60 DAMAGED RIB BEADS 152 61 DAMAGED RIB CUTOUTS 152 62 BUCKLED RIB WEBS 153 63 DAMAGED RIB FLANGES 153 64 SPLICING TYPICAL RIBS 154 65 REMOVING AND REPLACING DAMAGED RIBS- • 155 66 WING JOINT BOLTING ANGLES 155 67 WING JOINT COVERS 157 68 EXTRUDED ALUMINUM REPAIR MATERIAL- - - 158 69 ALCLAD SHEET REPAIR MATERIAL 158 70 RIVETS, BOLTS, SCREWS, AND NUTS RE- QUIRED FOR REPAIR 158 71 REPAIR TOOLS 159 SECTION 4 MOVABLE SURFACES 1 GENERAL 161 2 LANDING FLAP CONSTRUCTION 161 3 RUDDER CONSTRUCTION 161 4 ELEVATOR CONSTRUCTION 163 5 AILERON CONSTRUCTION 164 6 RUDDER, ELEVATOR, AND AILERON ORIGINAL FABRIC COVERING 164 7 CONTROL SURFACE TRIM AND BOOSTER TABS- 166 8 FLAP REPAIR, GENERAL 166 Par. Page 9 FLAP SKIN REPAIR 166 10 FLAP CHANNEL SPAR 167 11 FLAP LEADING EDGE 168 12 FLAP TRAILING EDGE 168 13 STRUCTURAL REPAIR OF RUDDER, ELEVA- TORS, AND AILERONS, GENERAL 169 14 ELEVATOR AND RUDDER RIB REMOVAL. ... 169 15 ELEVATOR AND RUDDER RIB REPLACEMENT. - 170 16 ELEVATOR AND RUDDER LEADING EDGE SKIN REPAIR 170 17 RUDDER, ELEVATOR, AND AILERON TRAILING EDGE STRIP REPLACEMENT 171 18 AILERON SPAR SPLICE 171 19 AILERON TRAILING EDGE RIB REPLACEMENT- 172 20 AILERON NOSE RIB REPLACEMENT 173 21 AILERON LEADING EDGE SKIN REPAIR ... 175 22 GENERAL FABRIC PATCHING 175 23 TESTING FABRIC FLEXIBILITY 175 24 SMALL FABRIC TEARS 176 25 V-SHAPED FABRIC TEARS 176 26 LARGE TEARS AND HOLES IN FABRIC- - - - 177 27 FABRIC SECTION REPLACEMENT 177 28 PARTIAL FABRIC RE-COVERING 178 29 REMOVAL OF ENTIRE FABRIC COVERING- - - 179 30 PREPARING NEW FABRIC ENVELOPE 183 31 ATTACHING OF THE NEW FABRIC ENVELOPE COVER 183 32 HAND SEWING FABRIC ENVELOPE AFTER ATTACHMENT 18U 33 DOPING FABRIC - GENERAL 185 34 FABRIC DOPING PROCEDURE 186 35 CONTROL SURFACE STATIC BALANCE .... 186 36 DETERMINING CONTROL SURFACE UNBALANCE- 187 37 CORRECTING UNBALANCE WHEN ABOVE LIMIT- 188 38 METAL AND FABRIC REPAIR TOOLS 189 39 METAL STRUCTURE REPAIR MATERIALS - - - 191 40 RUDDER COVERING MATERIALS 191 41 ELEVATOR COVERING MATERIALS 192 42 AILERON COVERING REQUIREMENTS 193 SECTION 5 FUEL AND OIL SYSTEMS 1 GENERAL 19U 2 STRUCTURAL DESCRIPTION 19U 3 GENERAL REPAIR 194 4 cOCATiNG SMALL CRACKS 195 5 SEALING SMALL CRACKS 197 6 REMOVING DENTS 198 7 SPLIT SEAM REPAIR 198 8 LARGE CRACK AND HOLE REPAIR 199 9 HYDRAULIC OIL TANK REPAIRS 199 10 TESTING 199 11 REPAIR TOOLS AND MATERIALS 199 [iii ] RESTRICTED CONTENTS RESTRICTED Par. Page Par. Page OIL COOLERS 12 GENERAL 20 2 13 OIL COOLER CONSTRUCTION 202 14 CLEANING OIL COOLERS 202 15 TESTING OIL COOLER FOR LEAKS .... 202 16 REMOVING SINGLE TUBES 203 17 REPLACING TUBES 203 18 REMOVING LARGE SECTIONS OF CORE ... 203 19 LEAKS ON CORE SURFACE 203 20 LEAKS AROUND SHELL SEAMS 2O3 21 DENTS IN SHELL 203 22 HOLES IN SHELL 203 23 TESTING OIL COOLERS 2O3 2U OIL COOLER REPAIR MATERIALS 205 25 OIL COOLER REPAIR TOOLS 205 SECTION 6 LANDING GEAR 1 GENERAL 206 2 MAIN LANDING GEAR 206 3 TAIL WHEEL 206 4 REMOVAL OF WHEEL ASSEMBLY 207 5 REMOVAL AND INSPECTION OF TIRE AND TUBE 207 6 WHEEL INSPECTION AND REPAIR 208 7 NEW CASING REPAIR 208 8 CASING REPAIRS 208 9 TREADING 209 10 MARKINGS 209 11 TUBE REPAIR 209 12 TIRE AND TUBE BALANCE 209 13 TUBE BALANCING 210 14 TIRE BALANCING 210 15 ASSEMBLING TIRE AND TUBE ON WHEEL . . 211 16 MOUNTING TAIL WHEEL TIRE AND TUBE . . 212 17 TOOLS 215 18 MATERIALS 215 SECTION 7 CONTROL CABLES 1 GENERAL 216 2 NEGLIGIBLE DAMAGE 216 3 CABLE REPLACEMENT 216 4 CABLE FABRICATION 216 5 MATERIAL SPECIFICATIONS 216 6 CUTTING CABLES 216 7 RUST PREVENTION 216 8 SWAGED TERMINALS 218 9 SWEAT-SOLDERED TERMINALS 220 10 WOVEN SPLICED TERMINALS 220 11 WRAPPED-SOLDERED TERMINALS 221 12 TESTING 222 13 COLOR BANDING 222 14 TOOLS 222 SECTION 8 ELECTRICAL SYSTEM 1 GENERAL 223 2 WIRING 223 3 WIRE NUMBERING 223 4 WIRE REPLACEMENT 223 5 WIRE TERMINALS 224 6 ATTACHING CRIMPED TERMINALS 224 7 CONDUIT 225 8 BONDING 225 9 ELECTRICAL REPAIR TOOLS AND MATERIALS 227 SECTION 9 MISCELLANEOUS TUBES AND TUBING REPAIRS 1 GENERAL 229 2 TUBE JOINTS 229 3 FORMING FLARED TUBE JOINTS 229 4 FORMING BEADED TUBE JOINTS 229 5 GENERAL TUBING REPAIR 230 6 REPAIR OF HIGH-PRESSURE TUBING ... 230 7 LOW-PRESSURE LINE REPAIR 231 8 CONDUIT REPAIR 232 9 MISCELLANEOUS 232 10 TOOLS 232 11 MATERIALS 233 CHERRY BLIND RIVETS 12 GENERAL 233 13 SELF-PLUGGING CHERRY RIVETS 233 14 TYPES OF SELF-PLUGGING CHERRY RIVETS 234 15 DETERMINING CHERRY RIVET GRIP LENGTH 235 16 DRILLING PREPARATIONS 235 17 DIMPLING PREPARATIONS 235 18 SHEET CLAMPING 235 19 CHERRY RIVET INSERTION 235 20 TYPES OF CHERRY RIVET GUNS 236 21 USE OF CHERRY RIVET GUNS 236 22 CHERRY RIVET GUN MAINTENANCE .... 237 23 TRIMMING CHERRY BLIND RIVETS .... 238 DU PONT EXPLOSIVE RIVETS 24 GENERAL 238 25 RIVETING PRECAUTIONS 238 26 STORAGE AND HANDLING PRECAUTIONS • . 238 RESTRICTED [iv] RESTRICTED CONTENTS Par. Page 27 RIVET INSTALLATION > . . 239 28 DU PONT RIVETING IRONS 239 RIVNUTS 29 GENERAL 239 30 TYPES OF RIVNUTS 239 31 GRIP RANGE 239 32 RIVNUT TYPE NUMBERS 240 33 STRENGTH OF RIVNUTS 240 3^ PREPARATIONS FOR INSTALLATION .... 241 35 RIVNUT INSTALLATION 241 DZUS FASTENERS 36 GENERAL 242 37 REMOVING LIGHT-DUTY DZUS FASTENERS . 242 38 REPLACING LIGHT-DUTY DZUS FASTENERS . 242 39 REMOVING HEAVY-DUTY DZUS FASTENERS . 244 40 INSERTING NEW FASTENER ....... 244 TRANSPARENT PLASTIC PANELS 41 CLEANING 244 42 MINOR SCRATCHES 244 43 DEEP SCRATCHES 244 44 REPAIRS - GENERAL 245 45 ISOLATED CRACKS 245 46 REPAIRING HOLES 246 47 PREPARATION OF NEW CURVED PANELS . . 246 48 ROUTING EDGES OF PANELS 247 49 ROUTING INSIDE CURVES 247 50 COCKPIT ROOF PANEL REPLACEMENT ... 248 51 SIDE PANEL REPLACEMENT 248 ALUMINUM CASTINGS AND FORGINGS 52 GENERAL 249 53 MINOR SURFACE CRACKS 249 54 MINOR WELDING OF LOWLY STRESSED MEN^ BERS 249 PROPELLER 55 Ml NOR REPAI RS 250 WOODEN ACCESSORIES 56 WOODEN COCKPIT SEATS 250 57 WOODEN FLOOR BOARDS 250 58 MINOR WOODEN ACCESSORIES 251 CONTROL RODS 59 GENERAL 251 Par. 60 61 62 63 NEGLIGIBLE DAMAGE SPLICING CONTROL RODS FABRICATING REPLACEMENT RODS . . , REPLACING DAMAGED ROD END FITTINGS ARMAMENT INSTALLATION REPAIRS Page 251 251 252 252 64 GENERAL 253 SECTION 10 REBUSHING SPEC IF ICATIOHS GENERAL 254 SECTION II FINISH SPECIFICATION 1 GENERAL REQUIREMENTS 257 2 FINISH AND FINISH MATERIAL SPECIFI- CATIONS 257 3 FI NISH CODE 258 ALUMINUM AND ALUMINUM ALLOYS 4 GENERAL FA-0 258 5 INTERIOR CLOSED MEMBERS FA-20 .... 258 6 INTERIOR SURFACES, PARTS, AND OPEN MEMBERS FA-21 258 7 ENGINE COMPARTMENT SURFACES FA-23 . • 258 8 EXTERIOR SURFACES, PARTS, AND MEMBERS FA-25 258 9 INSTRUMENT PANELS FA-28 258 10 ELECTRICAL AND RADIO JUNCTION BOXES AND CONDIUT FA-29 258 11 GENERAL FC-G 260 12 COPPER LINES FC-20 260 13 DISSIMILAR METALS FC-23 260 GENERAL FINISHES 14 CHROMIUM PLATE FG-0 260 15 DISSIMILAR METALS FG-5 260 16 STEPS FG-7 260 17 WALKWAYS FG-8 260 18 COIL SPRINGS FG-10 260 19 FLAT SPRINGS FQ-ll 261 20 ARMAMENT PROTECTION FG" 13 2-^1 21 MARKINGS: LINES FG-21 261 22 MARKINGS: CABLES, CRANKS, AND HORNS FG-22 261 23 MARKINGS: MISCELLANEOUS FG-23 ... 261 24 MARKINGS: ENGINE DISCONNECT POINTS FG-24 261 [v] RESTRICTED ILLUSTRATIONS RESTRICTED Par. Page Par. Page MAGNESIUM AND MAGNESIUM ALLOYS TEXTILES 25 GENERAL FM-0 263 26 EXTERIOR SURFACES, PARTS, AND MEMBERS FM-20 263 27 ENGINE COMPARTMENT SURFACES, PARTS, AND OPEN MEMBERS FM-23 263 28 INTERIOR SURFACES, PARTS, AND MEMBERS FM-25 263 PLASTICS 29 INTERIOR SURFACES, PARTS, AND MEMBERS FP-21 263 30 EXTERIOR SURFACES, PARTS, AND MEMBERS FP-23 263 31 INTERIOR OF CLOSED MEMBERS FP-24. . . 263 STEEL 32 GENERAL FS-0 263 33 EXTERIOR SURFACES, PARTS, AND OPEN MEMBERS THAT CAN BE PLATED FS-20. . 263 34 EXTERIOR CLOSED MEMBERS THAT CAN BE PLATED FS-21 263 35 EXTERIOR CLOSED MEMBERS THAT CANNOT BE PLATED FS-22 264 36 ENGINE COMPARTMENT SURFACES FS-23 • • 264 37 INTERIOR SURFACES, PARTS, AND OPEN MEMBERS THAT CAN BE PLATED FS-26. • 264 38 INTERIOR CLOSED MEMBERS THAT CANNOT BE PLATED FS-27 264 39 INTERIOR CLOSED MEMBERS THAT CAN BE PLATED FS-28 264 40 TANK PADS AND STRAPS FT-20 264 41 ELEVATORS AND AILERONS FT-21 RUDDER FT-23 264 42 ANTENNA MAST FT-24 264 43 COTTON WEBBING AND FABRIC FT-25 ... 264 WOOD 44 GENERAL REQUIREMENTS 265 45 TYPES OF WOOD SURFACES 265 46 DETAIL REQUIREMENTS 265 47 APPLICATION OF SEALER 265 48 APPLICATION OF FILLER 265 49 APPLICATION OF SURFACER 265 50 APPLICATION OF FINISH COATS TO TYPE I I SURFACES 265 51 APPLICATION OF FtNISH COATS TO TYPE I I I SURFACES 265 52 FINISHING EXPOSED END-GRAIN SURFACES NOT SUITABLE FOR TAPfNG 266 53 FINISHING EXPOSED END-GRAIN SURFACES SUITABLE FOR TAPING 266 54 SANDING S.EALER, FILLER, AND SURFACER COATS 266 SECTION 12 HEAT-TREATED PARTS 1 GENERAL 267 2 MATERIAL CODE 267 3 HEAT-TREATED PARTS LIST 268 Fig. 1 2 3 4 5 6 7 8 9 10 11 12 13 LIST OF ILLUSTRATIONS Page Fig. Page SECTION I GENERAL INSTRUCTIONS TYPES OF RIVETS GENERAL AIRPLANE DATA AIRPLANE THREE-VIEW DIMENSIONS. NAA PART NUMBERS TYPICAL CENTER-PUNCH MARKS- • . USING RIGHT-ANGLED DRILL. . . . RIVET COUNTERSINKING CUT COUNTERSINKING DIMPLE COUNTERSINKING SKIN FASTENERS CLECO COLOR CODING TYPICAL RIVET SETS RIVET BUCKING BARS RESTRICTED LLUSTRATI0N3 Fi^' Page 29A EXTRUSION EQUIVALENT CHART (CONTD.) .... 21 30 STRESS CONCENTRATIONS 22 31 PRIMING ALUMINUM SHEET 22 32 STANDARD TOOL KIT 23 33 METAL SHRINKER AND STRETCHER 23 34 HAND ROLLER 24 35 HAND BRAKE 2U 36 BENDING SHEET STOCK LOCALLY 24 37 ARBOR PRESS 25 38 FORMING BLOCK 25 39 TRIMMING MACHINE 26 40 USE OF SPIRAL REAMER 26 41 STANDARD POWER AND HAND TOOLS 29 42 STANDARD METAL-WORKING HAND TOOLS 3I SECTION II FUSELAGE FUSELAGE STATIONS . . . 34 ENGINE MOUNT & FRONT FUSELAGE TUBE SIZES . 35 ENGINE MOUNT TRUSS ASSEMBLY 36 FRONT FUSELAGE TRUSS ASSEMBLY 37 UPPER TUBE CLUSTER JOINT AT STA. 55 ... . 38 ARC WELDING GENERATOR WITH CRATER ELIMINATOR 38 ARC WELDING ELECTRODE REQUIREMENTS .... 39 TYPICAL WELD ENDS 39 TYPICAL ARC-WELDED ENGINE MOUNT JOINT ... 39 OXYACETYLENE WELDING EQUIPMENT 40 TYPICAL WELDING FAILURES 4O CORRECTING OVAL-SHAPED STEEL TUBE DISTORTION 41 STRAIGHTENING BOWED STEEL TUBES 42 APPLICATION OF FINISH TO STEEL TUBES ... 43 REINFORCING A DENT AT A STEEL TUBE CLUSTER JOINT 43 REINFORCING A DENT OR CRACK IN STEEL TUBE LENGTH 44 STEEL TUBE INNER SLEEVE SPLICE 45 CENTERING INNER SLEEVE IN STEEL TUBE ... 48 STEEL TUBE OUTER SLEEVE SPLICE 49 STEEL TUBE FISHMOUTH SPLICE USING LARGER DIAMETER REPLACEMENT TUBE .... 50 STEEL TUBE DIAGONAL SPLICE USING LARGER DIAMETER REPLACEMENT TUBE .... 51 EXHAUST MANIFOLD ASSEMBLY 51 EXHAUST MANIFOLD ASSEMBLY EXPLODED .... 52 EXHAUST MANIFOLD SLIP JOINT 52 ENGINE FIREWALL ASSEMBLY 53 FIREWALL WEB REPAIR 54 FIREWALL WIDE-FLANGED STIFFENER SPLICE . . 54 FIREWALL NARROW-FLANGED STIFFENER SPLICE . 55 ENGINE COWLING CONSTRUCTION 55 ENGINE COWLING ASSEMBLY 56 FRONT FUSELAGE SIDE PANELS 57 FRONT FUSELAGE SIDE PANEL FORWARD FORMER SPLICE 57 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 ^i^' Page 33 ALUMINUM REAR FUSELAGE COVERED ASSEMBLY . . 58 34 ALUMINUM REAR FUSELAGE PART NUMBERS .... 59 35 SPLICE OF REAR FOUR FORMERS OF FRONT FUSELAGE SIDE PANELS 60 36 ATTACHMENT OF FRONT TRUSS TO ALUMINUM REAR FUSELAGE 60 37 ALUMINUM REAR FUSELAGE INTERIOR 61 38 ALUMINUM REAR FUSELAGE INTERIOR EXPLODED . 61 39 ALUMINUM REAR FUSELAGE FORMER SPLICE ... 62 40 FABRICATING REPLACEMENT FORMERS 62 41 SPLICE FOR STRINGER TYPE C107LT-40 .... 63 42 SPLICE FOR STRINGER TYPE C234LT 64 43 ALUMINUM REAR FUSELAGE BAGGAGE COMPARTMENT INTERCOSTAL ANGLE SPLICE . • 65 44 SPLICE FOR STRINGER TYPE C364LT 66 45 ALUMINUM REAR FUSELAGE DOORS 66 46 ALUMINUM REAR FUSELAGE UPPER LONGERON SPLICE 67 47 ALUMINUM REAR FUSELAGE LOWER LONGERON SPLICE 68 48 FUSELAGE SKIN ARRANGEMENT 69 49 PLASTIC FAIRINGS AND FILLETS 70 50 INTERIOR VIEW OF WOODEN FUSELAGE 71 51 ALUMINUM ALLOY REINFORCEMENT OF WOODEN FITTINGS 71 52 WOODEN REAR FUSELAGE FRAME ASSEMBLY .... 72 53 INTERIOR VIEW OF FUSELAGE SHOWING SKIN GRAIN DIRECTION 73 54 ATTACHMENT OF LOWER STEEL LONGERON TO REAR WOODEN FUSELAGE 73 55 MIXING CASEIN GLUE 74 56 ATTACHMENT OF UPPER STEEL LONGERON TO REAR WOODEN FUSELAGE 74 57 APPLYING CASEIN GLUE WITH BRUSH 75 58 CORRECT EQUALIZED APPLICATION OF GLUING PRESSURE 75 59 INCORRECT CONCENTRATED APPLICATION OF GLUING PRESSURE 76 60 USING NAILING STRIPS TO APPLY GLUING PRESSURE TO SKIN 77 61 TYPES OF CLAMPS FOR WOOD 77 62 WOODEN REAR FUSELAGE STRINGER SPLICE ... 78 63 REMOVING PORTION OF DAMAGED WOOD STRINGER ADJACENT TO SCARF CUT 78 64 BAGGAGE COMPARTMENT WOODEN INTERCOSTAL SPLICE 79 ^5 SMOOTHING SCARF CUT WITH A WOOD PLANE ... 79 66 WOODEN REAR FUSELAGE UPPER LONGERON. SPLICE 80 67 CHECKING SCARF CUT WITH STRAIGHTEDGE ... 80 68 CUTTING WOOD SCARF JOINT 81 69 WOODEN REAR FUSELAGE SKIN ARRANGEMENT ... 81 70 WOODEN REAR FUSELAGE LOWER LONGERON SPLICE 82 71 FLUSH PATCH FOR PLYWOOD SKIN HOLES LESS THAN 2 INCHES WIDE 83 72 EXTERNAL PATCH FOR PLYWOOD SKIN HOLES LESS THAN 2 INCHES WIDE 84 [vii ] RESTRICTED ILLUSTRATIONS RESTRICTED Fig. Page Fig. Page 73 SCARFING PLYWOOD SKIN WITH SPOKESHAVE ... 85 7ii PLYWOOD SKIN SECTION REPLACEMENT 86 75 WOODEN REAR FUSELAGE FORMER SPLICE .... 87 76 TYPES OF SAWS 87 77 TYPES OF FILES FOR WOOD 88 78 TYPES OF PLANES FOR WOOD 88 79 FINISH REQUIREMENTS FOR WOOD 89 SECTION 3 FIXED SURFACES 1 CENTERSECTION RIB AND SPAR PART NUMBERS . • 92 2 OUTER WING RIB AND SPAR PART NUMBERS . . » 93 3 CENTERSECTION FUEL TANK COMPARTMENT DOORS • 94 U ALUMINUM HORIZONTAL STABILIZER STRUCTURE • 95 5 WOODEN HORIZONTAL STABILIZER STRUCTURE • • 96 6 REAR SPAR JOINT OF WOODEN HORIZONTAL STABILIZER 97 7 WOODEN HORIZONTAL STABILIZER FRONT SPAR FITTING 97 8 VERTICAL STABILIZER RIB AND SPAR PART NUMBERS 98 9 AT-6A WING STRINGER ARRANGEMENT AND STATIONS 99 10 AT-6B AND AT-6C WING STRINGER ARRANGEMENT AND STATIONS 100 11 AT-6B AND AT-6C RIGHT OUTER WING UPPER SURFACE STRINGER DETAILS 101 12 AT-6B AND AT-6C RIGHT OUTER WING LOWER SURFACE STRINGER DETAILS 101 13 AT-6A STABILIZER STRINGER ARRANGEMENT ... 102 lU AT-6B AND AT-6C STABILIZER STRINGER ARRANGEMENT 102 15 SUMMATION OF STRINGER TYPES USED IN FIXED SURFACES 103 16 SPLICE FOR STRINGER TYPE C107LT-20 .... lOU 17 SPLICE FOR STRINGER TYPE C123LT ...... 104 18 SPLICE FOR STRINGER TYPE C148T 105 19 SPLICE FOR DOUBLED C148T TYPE STRINGERS . . 105 20 SPLICE FOR STRINGER TYPE C180T 106 21 SPLICE FOR STRINGER TYPE C204T 106 22 SPLICE FOR DOUBLED C204T TYPE STRINGERS . . 107 23 SPLICE FOR STRINGER TYPE C250T 107 24 SPLICE FOR DOUBLED C250T TYPE STRINGERS . • 108 25 SPLICE FOR COMBINATION C250T-C366T STRINGERS 108 26 SPLICE FOR STRINGER TYPE C265T 108 27 SPLICE FOR STRINGER TYPE C266T 109 28 SPLICE FOR STRINGER TYPE C274T HO 29 SPLICE FOR STRINGER TYPE C366T HO 30 SPLICE FOR DOUBLED C366T TYPE STRINGERS . • 111 31 SPLICE FOR STRINGER TYPE C373LT 112 32 SPLICE FOR STRINGER TYPE K77A 112 33 SPLICE FOR DOUBLED K77A TYPE STRINGERS • . 113 34 SPLICE FOR WING TRAILING EDGE 113 35 OUTER WING MAIN SPAR 114 36 OUTER WING MAIN SPAR SPLICE- ROOT TO 106 INCHES OUTBOARD 115 37 OUTER WING MAIN SPAR SPLICE" 106 TO 151 INCHES OUTBOARD OF ROOT ... 117 38 OUTER WING MAIN SPAR SPLICE- 151 INCHES OUTBOARD TO TIP 118 39 OUTER WING FLAP SPAR SPLICE 120 40 OUTER WING AILERON SPAR SPLICE 121 41 CENTERSECTION FLAP SPAR SPLICE 123 42 CENTERSECTION REAR SPAR 124 43 CENTERSECTION REAR SPAR SPLICE 125 44 CENTERSECTION FRONT SPAR 126 45 CENTERSECTION FRONT SPAR UPPER CAP SPLICE 127 46 CENTERSECTION FRONT SPAR LOWER CAP SPLICE 128 47 CENTERSECTION FRONT SPAR WEB REPAIR ... 129 48 VERTICAL STABILIZER FRONT SPAR SPLICE . . 131 49 VERTICAL STABILIZER REAR SPAR SPLICE FOR AREA ABOVE ROOT RIB 133 50 VERTICAL STABILIZER REAR SPAR SPLICE FOR AREA BELOW ROOT RIB 13^ 51 HORIZONTAL STABILIZER FRONT SPAR SPLICE . 135 52 HORIZONTAL STABILIZER REAR SPAR SPLICE FOR AREA OUTBOARD OF CENTER HINGE FITTING 136 53 WING SKIN ARRANGEMENT 137 54 STABhLIZER SKIN ARRANGEMENT 138 55 SKIN REPAIR FOR HOLES LESS THAN 1/2-INCH DIAMETER 139 56 USING HOLE SAW TO TRIM SKIN DAMAGE .... 139 57 PATCH FOR SKIN HOLES l/2-TO 1-INCH DIAMETER 140 58 PATCH FOR 1-INCH DIAMETER SKIN HOLES NEAR ADJACENT STRUCTURE 141 59 ARRESTING GROWTH OF CRACK 141 60 TYPICAL FLUSH PATCH FOR LARGE SKIN HOLES . 142 61 USING SPIRAL REAMER TO TRIM SKIN DAMAGE • 142 62 TYPICAL EXTERNAL PATCH FOR LARGE SKIN HOLES 143 63 TEMPORARILY SECURING SKIN PATCH PRIOR TO RIVETING 143 64 LOCATING BLIND RIVET HOLES BY IMPROVISED METHOD 143 65 DRILLING OUT RIVETS COVERED BY SKIN PATCH 143 66 BLIND RIVET HOLE LOCATING TOOL 144 67 USING BLIND RIVET HOLE LOCATING TOOL ... 144 68 BLIND RIVET HOLE LOCATING TOOL WITH PILOT BUSHING 144 69 TYPICAL SKIN SPLICE 144 70 WING LEADING EDGE SKIN SPLICE 145 71 OUTER WING LEADING EDGE CONTOURS 146 72 GAINING ACCESS TO THE OUTER WING LEADING EDGE 147 73 USE OF DRIFT PUNCH WHEN RIVETING CLOSING STRIP SKIN 147 74 USE OF DRILL AT CLOSING STRIP SKIN .... 147 75 WELDING A ROD TO A DENT IN THE HORIZONTAL STABILIZER TIP 148 RESTRICTED [ V i i i ] RESTRICTED LLUSTRATIONS Fig. Page Fig. Page 76 REMOVING DENT IN HOR. STAB. TIP 148 77 FUEL TANK COMP. COVER FORMER SPLICE ... 1U9 78 CENTERSECTION INTERMEDIATE CENTER RIB . . 149 79 CENTERSECTION END RIB 150 80 CENTERSECTION INTERMEDIATE RIB SPLICE . . 151 81 TRAILING EDGE RIB SPLICE 151 82 VIEW OF OUTER WING SECTION J52 83 TYPICAL RIBS 152 84 TYPICAL REPAIR OF BROKEN RIB BEADS .... 153 85 TYPICAL REPAIR OF BROKEN RIB CUTOUTS ... 153 86 TYPICAL REPAIR OF BUCKLED RIB WEBS .... 154 87 TYPICAL RIB FLANGE REPAIR WHERE FLANGE IS RIVETED TO SKIN 154 88 TYPICAL RIB FLANGE REPAIR WHERE FLANGE IS NOT RIVETED TO SK I N 155 89 TYPICAL RIB SPLICE 155 90 CUTTING REPLACEMENT RIB FORM BLOCKS ... 156 91 FORMING REPLACEMENT RIB 156 92 CENTERSECTION BOLTING ANGLE PART NUMBERS . 156 93 OUTER WING BOLTING ANGLE PART NUMBERS . . 156 94 INSTALLING LOWER PORTION OF WING JOINT COVER , 157 95 INSTALLING UPPER PORTION OF WING JOINT COVER 157 96 LOCATING BRACKET HOLE IN WING JOINT COVER 157 97 ASSEMBLING WING JOINT COVER 157 SECTION 1 MOVABLE SURFACES 1 LANDING FLAPS INSTALLED ON WING 161 2 LANDING FLAP PART NUMBERS 162 3 RUDDER FRAME PART NUMBERS 163 4 RUDDER INSTALLED ON VERTICAL STABILIZER . 164 5 ELEVATOR FRAME PART NUMBERS 165 6 ELEVATORS INSTALLED ON HOR. STAB 166 7 AILERON FRAME PART NUMBERS 167 8 LEFT AILERON INSTALLED ON WING 168 9 REPAIR OF ONE-INCH DIAMETER HOLE IN SKIN UNDER FLAP CHANNEL SPAR 168 10 FLAP CHANNEL SPAR SPLICE 169 11 FLAP LEADING EDGE SPLICE 170 12 RUDDER AND ELEVATOR RIB REPLACEMENT ... 170 13 FLAP TRAILING EDGE SPLICE 171 14 AILERON SPAR SPLICE 172 15 SEWING SMALL FABRIC TEAR 173 16 CUTTING OUT DAMAGED FABRIC 173 17 PATCHING V-SHAPED FABRIC TEAR 174 18 DAMAGE REQUIRING FABRIC SECTION REPLACEMENT 175 19 DAMAGED FABRIC SECTION REMOVED 176 20 FINAL FOLDING, PINNING, AND SEWING OF FABRIC SECTION 176 21 DETAIL OF FABRIC SECTION STITCHING .... 177 22 RUBBING DOWN REINFORCING TAPE AT SEAMS . . 177 23 APPLYING FINISHING TAPE ON FABRIC SECTION SEAMS 178 24 TYPICAL REMOVAL OF FABRIC FROM TWO OR MORE SECTIONS 178 25 REMOVING FABRIC RETAINING SCREWS .... 179 26 PULLING ON PARTIAL FABRIC ENVELOPE COVER 179 27 RUDDER FABRIC COVERING REQUIREMENTS ... 180 28 ELEVATOR FABRIC COVERING REQUIREMENTS . . 131 29 AILERON FABRIC COVERING REQUIREMENTS . . 182 30 FABRIC DOUBLE-STITCHING MACHINE 183 31 PULLING NEW FABRIC COVER OVER CONTROL SURFACE STRUCTURE 183 32 PINNING UNSEWED END OF FABRIC ENVELOPE . 184 33 TRIMMING THE UNSEWED END OF FABRIC ENVELOPE AFTER PINNING 184 3^ FABRIC PINNED AT TRIM TAB CUTOUT .... 185 35 CUTTING FABRIC AT TRIM TAB CUTOUT .... 185 36 ATTACHING FABRIC ALONG TRIM TAB CHANNEL . 186 37 CUTTING TAPE WITH HAND PINKING MACHINE . 186 38 ATTACHING FABRIC TO RIBS 187 39 HAND SEWING AT TRIM TAB CUTOUT 187 W USE OF PNEUMATIC SCREWDRIVER TO ATTACH FABRIC TO RIBS 188 41 HAND SEWING FABRIC AT HINGE CUTOUT ... 188 42 APPLYING BRUSH COAT OF DOPE TO FABRIC . . 188 43 HAND STITCHING THE UNSEWED END OF FABRIC ENVELOPE 188 44 APPLYING FINISHING TAPE TO FABRIC .... 189 45 FABRIC ENVELOPE PRIOR TO FIRST AND SECOND COATS OF DOPE 189 46 APPLYING SPRAY COATS OF ALUMlNlZED DOPE TO FABRIC 189 47 APPLYING BALANCE PATCH TO AILERON .... 189 48 DETERMINING CONTROL SURFACE UNBALANCE . • 190 49 RUDDER UNBALANCE LIMITS 191 50 AILERON UNBALANCE LIMITS 192 51 ELEVATOR UNBALANCE LIMITS 192 52 APPLYING BALANCE PATCH TO ELEVATOR AND RUDDER 193 SECTION 5 FUEL AND OIL SYSTEM 1 FUEL TANK SUPPORTS 194 2 FUEL TANK CONSTRUCTION 194 3 OIL TANK CONSTRUCTION 195 4 OIL TANK ASSEMBLY 195 5 OIL TANK AND OIL COOLER INSTALLATION . . 196 6 FUEL TANK TESTING JIG 197 7 SEALING SMALL CRACKS 198 8 WELDING SPLIT SEAMS 198 9 HYDRAULIC OIL TANK 199 10 FORMING AND WELDING INSERT 200 11 COMPLETED FUEL AND OIL TANK REPAIRS ... 201 12 OIL COOLER ASSEMBLY 202 13 OIL COOLER TUBE REPLACEMENT 204 [ix] RESTRICTED ILLUSTRATIONS RESTRICTED Fig. Page Fig, Page SECTION 6 LANDING GEAR 1 MAIN LANDING GEAR SHOCK STRUT 206 2 MAIN LANDING GEAR 206 3 TAIL WHEEL ASSEMBLY 207 4 TAIL WHEEL COMPONENTS 207 5 HYDRAULIC JACK CRADLE 207 6 REMOVING MAIN LANDING GEAR WHEEL 208 7 REMOVING TAIL WHEEL 209 8 BALANCE WHEEL 210 9 APPLYING CEMENT 210 10 APPLYING BALANCING DOUGH 211 11 APPLYING TIRE TALC TO BALANCING DOUGH . . 2ll 12 APPLYING TIRE TALC TO INFLATED TUBE ... 212 13 VALVE EXTENSION 212 14 TIRE AND TUBE MARKINGS 212 15 SPECIAL TIRE TOOLS 212 16 MOUNTING MAIN GEAR TIRE AND TUBE 213 17 MOUNTING TAIL WHEEL TIRE AND TUBE .... 214 18 APPLYING TIRE TALC TO TAIL WHEEL TUBE . . 215 SECTION 7 CONTROL CABLES 1 TYPES OF CABLES 217 2 CABLE DATA 218 3 PREPARATION OF A WOVEN CABLE SPLICE ... 219 4 PREPARATION OF A WOVEN CABLE SPLICE ... 219 5 TYPES OF CABLE TERMINALS 220 6 CABLE CLAMP FOR WOVEN SPLICE 220 7 WRAPPED SOLDERED SPLICE 221 SECTION 8 ELECTRICAL SYSTEM 1 TYPICAL WIRE ROUTING 223 2 SLIPPING INSULATION OVER WIRE 224 3 CABLE TERMINAL SWAGING 218 4 CRIMPING THE TERMINAL 225 5 SLIPPING INSULATION INTO POSITION .... 225 6 TYPICAL SWITCH BOX WIRING 226 7 TYPES OF TERMINALS 227 8 CONDUIT BONDING METHODS 227 9 ELECTRICAL REPAIR TOOLS 228 10 ELECTRICAL REPAIR MATERIALS 228 SECTION 9 MISCELLANEOUS 1 TUBE FLARING TOOLS 229 2 BEADING SMALL TUBING 230 3 BEADING LARGE TUBING 230 4 HIGH-PRESSURE TUBING REPAIR OF MAJOR DAMAGE 231 5 HIGH-PRESSURE TUBING REPAIR OF MINOR DAMAGE 231 6 LOW-PRESSURE TUBING REPAIR 232 7 CONDUIT REPAIR > 232 8 SPECIAL WRENCHES FOR HIGH-PRESSURE CONNECTIONS 233 9 CHERRY RIVET GRIP LENGTH 234 10 INSERTING CHERRY RIVETS 236 11 EXPANDING CHERRY RIVETS 236 12 UNTRIMMED CHERRY RIVETS 237 13 TRIMMING CHERRY RIVETS 237 14 CHERRY RIVET HAND GUN 237 15 EXPLOSIVE RIVET CROSS SECTION 238 16 USE OF EXPANDING IRON 238 17 USE OF KEYSEATING TOOL 240 18 INSERTING RIVNUT 240 19 SQUEEZING RIVNUT 241 20 REMOVING MANDREL 241 21 TYPICAL DAMAGE TO DZUS FASTENERS 242 22 DZUS FASTENER TOOL 242 23 LIGHT-DUTY DZUS FASTENER REPLACEMENT ... 243 24 REMOVING GROMMET 244 25 INSERTING GROMMET AND FASTENERS 244 26 REMOVING DEEP SCRATCHES IN TRANSPARENT PLASTIC PANELS 245 27 APPLYING HOT-AIR BLAST TO CRACKED PLASTIC PANEL 245 28 APPLYING TORCH FLAME TO A CRACKED TRANSPARENT PLASTIC PANEL 246 29 PATCHING HOLES IN PLASTIC PANELS 246 30 MODIFIED DRILLS FOR TRANSPARENT PLASTIC PANELS 246 31 PANEL ROUTING JIG 247 32 ROUTING INSIDE CURVES 247 33 CURVE ROUTING DETAIL 248 34 COCKPIT ENCLOSURE ASSEMBLY 248 35 PROPELLER INSTALLED 250 36 WOODEN COCKPIT SEAT 251 37 CONTROL ROD REPAIR COMPONENTS 251 38 CONTROL ROD SPLICE 252 39 CONTROL ROD FITTING REPLACEMENT 252 40 ARMAMENT INSTALLATIONS 253 SECTION 11 FINISH SPECIFICATION 1 ENGINE DISCONNECT POINTS 259 2 LINE COLOR CODING CHART 260 3 AIRPLANE INSIGNIA LOCATIONS 262 RESTRICTED I - ] EESTRICTED INTRODUCTION TO THE REPAIRMAN: In the preparation of this Manual, an attempt has been made to include extensive and complete informa- tion for the repair of damaged structural and nonstructural parts of the airplane. It is intended that this Repair Manual will facilitate the restoration of the airplane to active service within a minimum of elapsed time and with a minimum of replacement parts. If spare or replacement parts are required, they ma^y be ordered as out I ined below. The repairs outlined in this Manual provide for the repair of any daniaye to any part of the aircraft and are not based upon any preconceived idea as to the extent of damage. Since the scope of possible damage is so broad it would be impossible to outline any exact procedure, only general repa i r methods are described and illustrated. These methods may have to be supplemented and altered to suit each spe- cific situation. The material requirements, rivet specifications, etc., are the minimum al lowable; and for the repair of any important structural components, personnel are warned against the use of any method of repair not described herein. A complete explanation of each repair is outlined in the text. The illustrations should not be con- strued as being self-explanatory. The scheme of arrangement of each section is similar, deal Tng first with the description, then with repair procedures, materials, and tools required for making ttie various repairs. A thumb index has been inserted at the outside top of each page for quick identification of the section title and paragraph number. For convenience, all common U. S. material specifications together with the British equivalents of these material specifications are listed at the end of Section I. Your cooperation in reporting your views on this N-lanual and the material contained herein will help substantial ly in the further development of a more adequate manual. Opinions on the matter are sol ic- ited and may be communicated to the company through the North American Service Representative at your field or sent directly to the Field Service Department at Inglewood, California. Field Sen/ ice Department North American Aviation, Inc. SPARE PARTS In many instances, incorrect part numbers, lack of complete infometion, and lack of part identifica- tion may cause delay in the filling of orders for spare parts. Requests by the company- for additional information, necessitated tiy these discrepancies, involve loss of time; and the need for such can be eliminated if the correct part number, name, and location are clearly set forth in the original request. To facilitate the prompt fulfillment of requests, observe the following rules: (I) Give correct part number and full title. (Refer to the applicable structures diagram in this Manual or to the Parts Catalog, T.O. No. 01-60FE-4J Example: 54-14015 left nose rib, station 15.087 (left wing, AT-6B) 88-I40I5-I right nose rib, station 15.087 (right wing, AT-6C) Note the prefix change for the AT-6C and that the part number ends with -I signifying a right-hand part. RESmiCTED [xi] NTRODUCTION restricted (2) Give the serial number and iiDdei of the airplane for which the part is intended. Example: Serial No. AC4-I-322I8, ^todel AT-6C (This infom^tion is stenciled in the upper left-hand corner on the left-hand front fuselage sTde panel and stamped on a name plate on the right- hand side of the front cockpit. ) (3) If the part number or name is not available, furnish the location and complete description of the part and the unit or system in which the part wi I I be used. Example: The second nose rib outboard of the bolting angle of the left-hand wing assembly, AT-6C, Serial No. AC4I-322I8. (4) Give conplete dash numbers and title of al I AN, AC, B, C, and NAF Standard Parts. Example: AN3-4A bolt, AC36^832 nut, BI289- 1(^10 screw, C384->5 neoprene extrusion, NAF3 1 062 1 -S2 1 [>- 4LH cable terminal. RESTRICTED [xii] RESTRICTED FRONTISPIECE .^^ •nrD-^ Three Views of Complete Airplane [ xiii ] RESTRICTED RESTRICTED GENERAL PAR. I TO ^ SECTION I GENERAL INSTRUCTIONS I. AIRPLANE CONSTRUCTION. The AT-6 Series Airplane is a single-engine, low-wing, two-place advanced trainer. General airplane data are tabulated in this Section. (See Figures 2 and ^.) The airplane is equipped with a Pratt and Whitney, nine-cylinder, radial, air-cooled engine on which is mounted a Hamilton Standard, controllable pitch, constant speed, two-blade propeller. The main landing gear is fully retractable and the nonretractab le tail wheel is full-pivoting. With the exception of the chrome molybdenum steel tubing front fuselage truss and engine mount, the airplane is primarily constructed of 24ST ale lad sheet and 24ST a I u- minum alloy extruded members. The front and rear fuselage sections, the outer wing panels, and the empennage are constructed to facilitate removal and replacement in the event of dafnage. All structural members are readily accessible and are fabricated in a manner as to provide for ease of repair. It is to be noted that multiplicity of types and sizes of component parts is confined to an absolute minimum in original construction of the airplane and also in repair. North American Aviation, Inc., major component part numbers are listed and illus- trated in this Section. (See Figure 4.) 2. RIVET TYPES. There are three different types of rivets used in the construction of the airplane (see Figure 1) . All a re made of A 1 7S a I um i num a I I oy mate- rial (rivet designation AD), and thus no heat treatment is required prior to driving. Rivets of AITS material are marked with an identifying dent or depression on the center of the manu- factured rivet head. These three types of rivets employed in the construction of the airplane are as fol lows: ( I ) the Type AN442-AD flat head rivet, used for the assembly of a I I interior structure; (2) the Type BI2I9-AD (superseded by Type AN426-AD for all future procurement) l(DO-degree countersunk head rivet, used to reduce drag on the forward skin of the fuselage and fixed surfaces; (3) the Type BI227-AD brazier head rivet, used on the aft skin of the fixed surfaces and fuselage. In making repairs, these types of rivets should be used in their original function. The rivet coding used throughout this ^.'lanua I specifies the type of rivet and the size. For example, a notation "AN442-AD5 rivet" signifies a flat head rivet of A|7S ma- terial. The last number of the rivet notation always signifies the rivet diameter in 1/52- inch. Therefore, the rivet diameter in this case is 5/32-inch. FLAT 100*.^ c'sunk' E^SSJD BRAZIER DIA. ^ "ft - AN442-AD BI2I9-AD BI227-AD (AN426-AD) APPROXIMATE DIMENSIONS DIA. 3/32 GENERAL FIGURE 2 RESTRICTED TABLE OF SPECIFICATIONS OVERALL W ING SPAN OVERALL LENGTH OVERALL HE IGHT ANTEN OVERALL HE IGHT ANTEN HE IGHT, PROPELLER HU CLEARANCE, PROPELLER DIAMETER OF PROPELLE NORMAL C.G. TO WING NORMAL C.G. TO W I NG C.G. LIMITS TO W ING ELEVATOR H I NGE TO Wl MINIMUM CLEARANCE OF ANGLE OF NORMAL C.G. ANGLE OF REARWARD C. ANGLE OF WING TIP AN ANGLE OF THRUST LINE NA MAST, THRUST LINE LEVEL NA MAST, THREE-POINT B, THRUST LINE LEVEL T IPS, THRUST LINE LEVEL R LEADING EDGE - WHEELS DOWN LEAD ING EDGE - WHEELS UP LEADING EDGE NG LEADING EDGE PROPELLER AND R ING COWL WITH WHEEL (Side Elevation) G. WITH WHEEL (Side Elevation) D WHEEL BOTTOM (Front Elevation) WITH GROUND (3-Point Position) 42 RESmiCTED GENERAL FIGURE 3 t STA. I t ELEVATOR HINGE ^1 RUDDER HINGE Figure 3 —Airplane Three-view Dimensions [3] RESTRICTED GENERAL FIGURE ^ RESTRICTED {«T-6») («T.6«) (»T-SO («T-St) (tr-e» (1T-«C) 77 an M 00002 77 ><4 98 K)OOI 66 10003 66 10001 66 I0O05 77 i% 88 13000 55 >« 88 IWOI 55 9H 88 I "4009 55 IW)M 78 l'tM2 66 8>t'. 80 ISOOl 55 16005 55 1800 66 18002 77 20001 55 20002 55 20003 55 20001 55 20005 55 20008 55 20O09 77 8* 8» 21001 66 22001 55 220 18 55 SU 8«....2»0I 77 2W)0I 55 211036 77 77 88 31001 77 77 88 31002-17 77 77 88 31002-18 77 77 S8 31002- 19 77 78 78 31010 77 78 78 31013 77 77 88 31027 77 77 88 31028 77 77 88 31030 77 31032 77 310 33 77 3103H 77 31035 77 310»2 77 31050 77 77 88. ...31051 55 31061 77 31065 77 31066 77 31075 77 31076 77 31077 AltrLME ASSUBLY CIMEKAL mSlALLAlIOH - Bines FIUET, KKG TO FUSanOt, FWIIT FILLET, milO TO FUSELtGE, mTERHEOI >TE tUt FILLH tSSEMBLY, MING TO FUSELAGE, I1E»II MING «SSE>l6Lr, CENTER SECTION COHFLETE COVERED JSSEMBLY, OUTER MING WGLE INSTtLLtTlON, OUTER MING BOLTING TIP tSSL-IBLT, MING DOOR ISSEMBLT, OUTER MING LW01N3 LIGHT IILERON tSSLISLT T»B «SSEHBLr, ilLERON BOOSTER FLU> tSSEMBLT, OUTER MING FLAP ASSEMBLY, MING CENTER SECTION IHSIALLAIION. ItFEHNACE FILLET ASSEMBLY, HORIZONTAL STABILIZER LEFT FRONT FILLH ASSEMBLY, VERTICAL STABILIZER TO FUSELAGE FILLET, HORIZONTAL STABILIZER, INTERMEOl ATE LOMER FILLET, HORIZONTAL STABILIZER, LEFT REAR FILLET, HORIZONTAL STABILIZER, »1 GHT REAR FILLET ASSEMBLY, HORIZONTAL STABILIZER, RIGHT FRONT STABILIZER ASSEMBLY, HORIZONTAL ELEVATOR ASSEMBLY, COVEREC TAB ASSEMBLY, ELEVATOR TRIM STABILIZER ASSEMBLY, VERTICAL RUDDER ASSEMBLY, COVERED TAB ASSEMBLY, RUDDER TRIM FVSELAGl ASSEtBLr COVEKED COMLING ASSEMBLY, ENGINE RING, LOMER COMLING ASSEMBLY, ENGINE RING, RIGHT HAND UPPER COMLING ASSEiHBLY, EKGINE RING, LEFT HAND UPPER COMLING ASSEMBLY, FUSELAGE FLEXIBLE GUN CUTOUT COMLING ASSEMBLY, FUSELAGE GUNNER'S HOOD COMLING ASSEMBLY, ENGINE REMOVABLE, CARBURETOR AIR S( COMLING ASSEMBLY, ENGINE REMOVABLE, UPPER RIGHT COMLING ASSEMBLY, ENGINE REMOVABLE, BOTTOM FAIRING ASSEMBLY, FUSELAGE FIREMALL UPPER LEFT SIDE COVER ASSEMBLY, FUSELAGE MAIN FUSE BOX ASSEMBLY FAIRING ASSEMBLY, FUSELAGE FIREMALL LOMER LEFT SIDE FAIRING ASSEMBLY, FUSELAGE FIREMALL UPPER RIGHT SIDE FAIRING ASSEMBLY, FUSELAGE FIREMALL LOMER RIGHT SIDE PANEL ASSEMBLY, FUSELAGE LEFT SIDE FAIRING PANEL ASSEMBLY, FUSELAGE RIGHT SIDE FAIRING COMLING ASSEMBLY, FUSELAGE TAllMHEEL CUTOUT COMLING ASSEMBLY, ENGINE REMOVABLE TOP COMLING ASSEMBLY, ENGINE REMOVABLE LOMER DOOR ASSEMBLY, FUSELAGE FIREMALL TO MINDSHIELO LEFT DOOR ASSEMBLY, FUSELAGE BAGGAGE COMPARTMENT DOOR ASSEMBLY, FUSELAGE FIREMALL TO MINOSHIELO RIGHT 77 77 88 3II0I 77 78 88 31104 77 31105 77 31106 55 31238 55 78 78 31211 77 77 88 31801 55 55 88....3I802 77 77 88 31826 55 55 88 31827 19 19 88 318 28 55 55 88 31829 77 31901 n 33001 77 78 78 33102 56 33»5 55 55 88 31001 58 58 88 31002 77 78 88 51001 77 78 88 51002 77 78 88 51003 55 55 88.. ..53001 55 55 88 53010 55 55 88. ...53 100 55 73101 55 55 88 73106 FKAIIE ASSEUBLY. fVSELACE COHrtElE FIREMALL ASSEMBLY, FUSELAGE FRAME ASSEMBLY, FUSELAGE FRONT FRAME ASSEMBLY, FUSELAGE REAR SECTION COVERED COVER ASSEMBLY, FUSELAGE REAR SECTION BODY ACCESS COVER ASSEMBLY, FUSELAGE REAR SECTION FLEXIBLE GUN TROUGH IKSIALLATIOn, COCKFIT EHCLOSVSE HOOD ASSEMBLY, GUNNER'S MINDSHIELD ASSEMBLY, COCKPIT ENCLOSURE PAfEL ASSEMBLY, COCKPIT ENCLOSURE, FRONT PANEL ASSEMBLY, COCKPIT ENCLOSURE, FIXED PANa ASSEMBLY, COCKPIT ENCLOSURE, REAR MOUNT ASSEMBLY, ENGINE inSTALLAH OK, LAUDING OEAR INS7ALLATI0N , TAIL WHEEL POST AND HOUSING ASSEMBLY, TAIL MHEEL IHSIALLAIION. INSIKVUENIS INSTALLATION, FUKMISHINCS INSTALLATION , FHOTOCRAFH IC EQVIFMEMT DOOR ASSEMBLY, CAMERA '<£' ^^^ Figure 4— North American Aviation Part Numbers RESTRICTED [4] RESTRICTED GENERAL PAR. H TO 6 should be center punched and the actual drilling done with a light power drill. The center- punch mark should be large enough to prevent the dri I I from si ipping out of position, yet must not be made with enough force to dent the surrounding material (see Figure ^}. The drill- ing can be done with a hand drill if no power tool is available, but considerably more time will be taken. Also, as the drill speed is slower when the work is done by hand, there is a tendency to apply more pressure; consequently, a large burr is often formed as the dri I I pierces the material. All burrs must be removed before riveting by utilizing a metal countersink, or Figure S-'Typical Center-punch Marks by filing or scraping. In some cases, the use of a right-angled drill is particularly advan- tageous in drilling through restricted access, small fittings, clips, etc. (see Figure 6). 5. STANDARD HOLES FOR RIVETS. The following chart specifies the size of hole to drill for the application of the various sizes of rivets. See the following paragraph for dri I I si zes. RIVET GENERAL PAR. 7 TO RESTRICTED 7. RIVET COUNTERSINKING DIMENSIONS. The following dimensions should be adhered to when cut countersinking or dimpling sheet material for the application of BI2I9-AD (or the AN426-AD) lOO-degree countersunk rivets. Use the proper degree and diameter countersink and cut just deep enough so the rivet head and the metal will forma flush surface. (See Figure 7 J RIVET SIZE RESTRICTED GENERAL PAR. 10 TO 12 drilled through, several varieties of skin fas- teners are availaole to line up holes. (See Figure 10.) Cleco skin fasteners are commonly r-SKIN FASTENER pRlVET GUN Figure 10 — Skin Fasteners used throughout the aircraft industry in pro- duction and repair work. Used in conjunction with a Cleco safety gun (see Figure 41), Clecos hold two pieces of metal firmly together until riveting is accomplished. Inasmuch as Clecos are used only through drilled holes, it is im- portant that the proper size oe used. The various sized Clecos are easily identified by their color coding. A Cleco for a 3/32-inch diameter hole is cadmium colored, copper colored for a 1/8- inch hole, Diack for a 5/32-inch hole, and brass colored for a 3/16-inch hole. (See Figure 11.) 11. BUCKING BARS. Sucking oars may assume any numoer of given shapes in order to facilitate rivet forming in inaccessible areas. (See Figure 13.) The rivet gun pressure applied to the manufactured head of the rivet forms the rivet shank against the Ducking oar. In similarity to rivet sets, rivet Ducking Dars must oe kept clean, smooth, and well polished at a I I times. 12. RIVET SETS. A rivet set is a punch-like tool with a flat >^'5S Figure 11 —Cleco Color Coding liHBRAZIER HEAD TYPE 4*AA^ FLUSH TYPE Figure 12 — Typical Rivet Sets [7] RESTRICTED GENERAL PAR. 12 TO 16 RESTRICTED liJX i U^TJ600-I TJ600-2 TJ600-5 JLJ TJ600-6 TJ 600-10 TJ600-28 aTJ 60 0-32 TJ600-42 TJ600-60 ] i f» TJ600-64 TJ600-65 TJ600-86 V J^ TJ600-90 TJ600-99 TJ600-106 Figure 13~-'Rivet Bucking Bars or recessed die for driving flat, countersunk, and brazier head rivets, respectively. They may assume a variety of shapes to facilitate rivet driving in restricted areas (see Figure 1^). Rivet sets should be kept smooth and well pel ished at al I times. 13. PNEUMATIC RIVET GUN. The pneumatic rivet gun used with a rivet set is applied to the manufactured head of the riv- et; and the pressure, applied in a series of vibrations, forms the rivet shank against a bucking bar. Different types are available to meet various requirements. (See Figure 14'\ The period of time during which pressure is applied to fonn the head must be short enough to prevent the metal from strain hardening near the end of the rivet. The pneumatic equipment may be used either with a flat or recessed rivet set, depending upon the type rivet being driven." Because of the uniformity of driving rivets pneumatically, all riveting should require this equipment. Both the rivet gun and the bucking bar are separate units requiring separate oper- ators. (See Figure lo. ) m. HAMMERS. Hartniers sometimes may have to be used to drive rivets, but they should be used only in emer- gencies where other equipment cannot be obtained. The use of hammers to drive rivets for the re- pair of primary structure is not recommended. On minor secondary structure, however, ball- peen hammers may sonietimes be employed. 15. RIVET SQUEEZER. A rivet squeezer consists of a large pair of forcers which are used over the edge of the TRIGGER Figure 14-^ Pneumatic Rivet Guns material to head the rivet. Pneumatic rivet squeezers may be used with alligator, offset alligator, and C-type jaws. Inasmuch as a rivet squeezer can be used only over the edge of the sheet where conditions permit, its appli- cation is necessarily limited. (See Figure 25.J 16. REMOVAL OF SOLID RIVETS. Rivet removal should be accomplished by drill- ing, not shearing. Use drill one size smaller than diameter of rivet, and place point into depression in rivet head. If power tool is used, locate drill first; then apply power in short bursts. Drill must be applied carefully and small cuts taken in a series of applications. Drill until rivet head twists from shank. (See Figure 16-) Drift remainder of rivet free. RESTRICTED [8] RESTRICTED GENERAL PAR. 16 TO 18 PNEUMATIC SQUEEZER Figure 15—Rivet Squeezer It is recommended that the drill be equipped with a stop of some soft nonabrasive material to prevent the drill chuck from plunging into and marring the surrounding metal. 17. RIVET AND BOLT EDGE DISTANCES. The necessity for providing adequate edge distances from the rivet or bolt to the edge of the affected material is of extreme impor- tance in repair. Generally, this distance should not be less than two times the diameter of the rivet or bolt, measured from the centerline of the rivet or bolt hole to the edge of the material involved. (See Figure ly- ) DRILL UNTIL RIVET HEAD TWISTS FROM SHANK, THEN PUNCH OUT RIVET Figure 16 '—Removal of Solid Rivets DISTANCE "E" SHOULD EQUAL TWICE THE RIVET DIAMETER h' f[ SECT. AA W'M ^ 1 INCORRECT -TOO CLOSE TO EDGE CORRECT E»2D RESULTANT CRACK SAFE Figure 17 — Rivet Edge Distance 18. RIVETING. Inasmuch as riveting is the major means of securing airplane parts, the quality of work- manship employed in driving rivets must be high. The structural efficiency of the completed prod- uct is greatly increased where power-driven tools are available. For this reason, the re- pair of primary structures should demand pneu- matically operated rivet-driving tools. However, for the repair of secondary structures, manually operated rivet-squeezing tools will suffice where conditions permit. The riveting of minor parts sometimes may be accomplished by means of a simple rivet set and bounce ball-peen hamrrer or the equivalent. Examples of correctly and incorrectly driven rivets are illustrated on the following diagram. (See Figure i8.) The following comments are made with reference to th is figure. a. Rivet (A) is driven correctly. The proper length has been determined and the rivet has been driven slowly and compressed evenly. The upset end of an und riven rivet of proper length should measure approximately 1-1/2 times the diameter of the rivet from the surface of the material being riveted. b. Rivet (B) is driven incorrectly. The head of the rivet has been cut by insecure and/or improperly held driving tool. Rivets damaged in this manner should be replaced. Damage of this nature may be prevented by holding the tool securely and as nearly in alignment with the rivet shank as possiole. [9] RESTRICTED GENERAL PARAGRAPH 18 RESTRICTED c. Rivet (C) is driven incorrectly. The rivet has been driven to excess and /or too much pres- sure has been applied to the bucking bar. As a result, the head has flattened excessively and cracks are attendant. In the majority of such cases, the cracks extend well into the shank of the rivet. Such conditions are ac- ceptable cause for failure of the rivet upon application of load. Rivets damaged in this manner must oe replaced. In the thinner sheet material, the rivet holes become enlarged to the extent that the sheet must be replaced. d. Rivet (D) is driven incorrectly. This condition is the result of failure to secure the sheets or parts together prior to riveting, thus causing creeping or distortion of the sheet. In this case, the shank of the rivet has swol I en into the area produced oy separation of the sheets. The rivet must be replaced. Dri M the rivet free oy means of a drill considerably smaller than its shank diameter; then follow with a dri I I equal in diameter to the estimated (A) (B) (C) diameter of the swollen portion. Special care should be exercised to prevent such occurrence, as it is most difficult to remove drill chips from between the sheets. Upon reriveting, a smooth surface cannot be obtained. Such con- ditions greatly lower the value of compressive load resistance of the joint. Various skin clamps can be used in connection with riveting to prevent this occurrence. (See Figure lo.) e. Rivet (E) is driven incorrectly. An un- balanced amount of head material is located about the centerl ine of the rivet and, as such, the efficiency of the rivet is impaired. This condition is a result of any one or a combin- ation of three things: the rivet bucking bar has not been held securely; it has been forced to one side oy pressing too hard without adequate support; or it has been permitted to bounce and slide carelessly over the rivet. This is a most common error and one which should receive much cond iderat ion. The rivet should be re- placed. (D) (£) (F) DRIVEN UNSTEADY DRIVEN SEPARATION UNSTEADY EXCESSIVE CORRECTLY RIVET SET EXCESSIVELY OF SHEETS TOOL SHANK LENGTH BOTTOM VIEW Figure 18^ Rivet Driving Practices RESTRICTED C 10] RESTRICTED GENERAL PAR. 18 TO 19 f. Rivet (F) is driven incorrectly. The rivet has failed laterally. This condition is a re- sult of improper selection of rivet length, combined with any one or all of the faults of rivet (E). Sufficient care must be exercised in proper selection of rivet length. A rivet too short in length does not permit the required amount of head material to be upset. Too much length results in a buckled shank. Driving a rivet of excessive length also presents possi- bilities of hole enlargement. 19. FITTING OF BOLTS AND SCREWS. All bolt holes should be the smallest con- sistent with design, and all bolts must be suit- ably locked. Always use the first drill size larger than the nominal diameter of the bolt. When in doubt, it is advisable to drill the hole undersize and ream for a close fit.. Bolt holes must not be oversized or elongated. A bolt in an oversized or an elongated hole takes none of the applied shear load until the metal it is holding in shear has slipped enough, and the remaining bolts sheared enough, to allow the bearing surface to come in contact with the bolt. (See Figure ig. ) This shearing action is a definite failure in these bolts and they are no longer capable of carrying their design loads. In some cases of over- sized or elongated holes, it is permissible to drill or reani the hole until large enough to permit the insertion of the next size larger bolt. However, before resorting to this method, obtain permission from an authorized engineering officer. When in doubt, it is advisable to replace the fitting, or fittings, which con- tains the oversized hole with one in which the holes are the proper size. To make a bolt in- stallation structurally sound, bolt threads -'^'-rN^ must never bear in any part of a fitting. All bolt holes must be normal to the surface in- volved and must provide complete bearing surface to the head and shank of the bolt. Also, any bolt entering an anchor nut must be free enough to engage the threads in the nut by hand manip- ulation. Although bolt threads must cut com- pletely through the fiber of self- locking nuts, there should be no more than two bolt threads showing beyond the fiber. To meet this require- ment, washers may be used under nuts, and shims may be added under nut plates. The bolts must be sufficiently tight, but too much twist on the wrench must also be avoided. The inch- pounds twist required should be within a certain range for the bolt diameter used. The following chart specifies the twist required. Inch-pounds is obtained by multiplying the pull by the wrench length or by the use of a toraue wrench which is calibrated in inch-pounds (see Figure 20). BOLT SIZE TWIST (INCH-POUNDS) AN3 A NU AN5 AN6 AN7 AN8 (1032 (1/U (5/16 (3/8 (7/16 (1/2 2 0-25 50-75 100-lUO 1 60-190 u 50-500 U80-690 Figure 19—Bolted Joint With Oversized Hole Figure 20 — Bolt Torque Measur ement Lii] RESTRICTED GENERAL PAR. 20 TO 23 RESTRICTED 20. TYPES OF BOLTS, SCREWS, AND NUTS. With respect to physical properties, bolts, screws, and nuts are of nickel steel and con- form to SAE Spec. 2330. Dimension specifica- tions conform to AN and B standards. These specifications, ooth physical and dimensional, must also be utilized in repair. Generally, only one type of do 1 1 and two types of screws are required in repair. These types are the AN4-type bolt, the BI248, lOO-degree countersunk screw, and the 8 1 25 1 button head screw. (See Figures 22,2'^, and 24.) The type of nuts used varies with the particular application. General types include the regular self- locking hexagonal, basket anchor, corner anchor, and gang channel (see Figure 2^). The self- locking hexagonal nut (elastic stop nut) can oe used in oil or gasoline, but it should not be used in the con- trol systems where the bolt would oe subject to rotation. For temperatures over I2I°C (25G°F), the Hy-Temp hexagonal nut should be used, rather than the regular type. It is to oe noted that the minumum hexagonal nut height is limited only Dy the strength requirements of the specifica- tion. In some cases, gang channels are partic- ularly useful, out they should not oe used in tension applications. The Boot's nuts in the gang channel may be spaced oy means of punch marks placed in the channel and they may be readily snapped in or out of the channel. In connection with olind anchoring, the basket anchor nut is also particularly useful, since it eliminates accurate jigging of holes. The corner anchor nut has a tendency to bend thinner gage sheet stock below .040 inch, and the stand- ard two- lug anchor nuts should be used wherever possible (see Figure 2^). 21. STANDARD HOLES FOR BOLTS AND SCREWS. The following chart specifies the sizes of holes to drill for the application of the var- ious sizes of bolts. It is to oe noted that bolt holes uti I ized in repai r should be dri I led undersize, then reamed for a close fit, wherever possi b I e. TYPE RESTRICTED GENERAL FIGURE 22 .4375 —ioio MARK FOR BRONZE THREAD 1/4- 28NF 3 « SPEC. AN-GG6-SI26 DRILL *48 (.076) CHAMFER 45* X gy OR ROUND END OP- TIONAL- END RAD. T MAXIMUM 2 IMPERFECT TH'DS. CHAMFER ON BOTTOM FACE IS*' TO DIM. 7/16 OPTIONAL DASH NOS. GENERAL FIGURE 23 RESTRICTED HEAD ANGLE 8 DIM. ARE RELATED DIM'S. DIM. V TO BE USED AS REFERENCE ONLY B' STAMP "X" INDENTED ON STEEL ONLY ioo*t r TOP FLAT UNSHAVED SHAVE CONCENTRIC WITH SHANK WITHIN TOTAL RUNOUT OF .005 THREAD CLASS 3 MAXIMUM 2 IMPERFECT TH'DS CHAMFER 1/32 X 45* ROLLED OR CUT THREADS OPTIONAL SIZE RESTRICTED GENERAL FIGURE 2^ MEASURED TO SHARP CORNERS STAMP "X" INDENTED ON STEEL ONLY .015 R. MAX. FOR 5/16 a 3/8 SIZES .OIOR. MAX. FOR * 8, ** 10 8 1/4 THREAD CLASS 3 MAXIMUM 2 IMPERFECT TH'DS CHAMFER 1/32 X 45** ROLLED OR CUT THREADS OPTIONAL SIZE GENERAL FIGURE 25 RESTRICTED DIMENSIONS SIZE a THREAD RESTRICTED 24. ALUMINUM WROUGHT STOCK - GENERAL. The symbol S is used after the formula number of wrought a I loys to distinguish them from the cast alloys. In the case of heat- treatab 1 e aluminum, the symbol fol lowing the S indicates an annealed material, but the symbol T following the S indicates a heat-treated, hardened mate- rial. Alloy 24ST in the form of sheet and ex- truded shapes is used almost entirely in the construction of the aircraft; but because of better forming qualities, parts are often fab- ricated of 24S0 and subsequently heat treated. Alloys I4ST and I7ST are used for forgings only. Material of I4ST, possessing high mechanical properties, is most prevalent in forgings. Material of I7ST finds use where an increase in corrosion resistance is required, with but a slight sacrifice in strength. See Section 12 for the required strength of forgings. The symbol W appl ies only to a I loys requiring arti- ficial aging and is used principally with the alloy 53SW to signify a heat-treated, quenched, but not completely age- hardened material. It is to be noted that the use of the symbol T to designate a hard alloy is applicable only to the heat-treatable alloys, principally 14ST, I7ST, and 24ST. However, of the wrought alloys, theri are a few which are nonheat-treatable, principally 2S, 3S, and 52S. These nonheat- treatable alloys are also nonstructural; but because of their malleability, they find par- ticular use in fairing and filleting. Cold working hardens these al loys to a certain extent and this condition is noted not by the symbol T but by the symbol H. Intermediate conditions of hardness are noted as I/4H, I/2H, etc. The foMoA/ing chart gives general particulars per- tinent to wrought alloy uses. ALLOY 14ST 17ST 2UST 24ST 53 ST 53SW 2S FORM FORGINGS SHEET, ALCLAD EXTRUDED SHAPES EXTRUDED SHAPES TUBE SHEET USE FITTINGS SKIN, SPARS, LONGERONS RIBS, FRAMES, FLOORS, FUSELAGE STRINGERS SPAR CAPS, WING STRINGERS, STIFFENERS ENCLOSURE & WINDOW FRAMES ONLY PLUMBING, LINES FAIR.ING-, FILLETING GENERAL PAR. 29 TO 311 RESTRICTED oy vi Drat ion, and does not require annealing after prolonged service. 30. ALUMINUM SHEET, 52S-I/2H. This alloy possesses the same chemical and mechanical properties as those of 52S0; Dut in similarity to the 2S-I/2H and 3S- I /2H alloys, it is hardened to an intermediate temper oetween the soft and hard oy cold working. The material finds general use in fillets and fairing where intermediate values of strength, hardness, and ductility are required. 31. ANNEALING ALUMINUM, 2S, 33, AND 523. The nonheat-t reataD I e alloys, 2S, 3S, and 52S, are sufficiently malleaole for cold work- ing in their original state. If these materials have already oeen strain hardened oy cold work- ing, annealing is instantaneous upon reaching the proper temperature, and the material should oe profdptly removed from the furnace and al- lowed to cool at normal room temperature. Hard- ness is accomplished only oy cold working. The following chart specifies annealing temperature part icu lars. ALLOY 2S 52S ANNEALING TEMPERATURE 329-371 385-U13 329-371 625-700 725-775 625-700 32. ALUMINUM EXTRUSIONS, 2US0. This material has values of corrosion resist- ance consideraoly inferior to 2S or 5S, Dut it possesses excellent working and forming quali- ties. The material is heat-treatable, Dut it does not work harden. Heat treatment orings its strength and hardness to a level fully equal to that of 24ST material. All 24S0 material must be heat treated after forming. Figure 26— Enlarged Cross Section of Ale lad Sheet Figure 27 — Typical Extruded Sections 33. ALUMINUM EXTRUSIONS, 2»IST. This material is the hardened form of 24S0 aluminum alloy. Extruded shapes of 24ST are extensively employed as stringers, longerons, and spar caps. (See Figure 21.) The 24ST alu- minum alloy composition is the strongest and hardest of al I the a! leys used, but the corrosion resistance of the material is consideraDly in- ferior to 24S alclad sheet. To protect the material against corrosion, zinc chromate primer must De applied to all surfaces. 34. ALUMINUM SHEET, 2i+S0 ALCLAD. This material is identical to 24S0 aluminum alloy; Dut in order to provide greater protec- tion against corrosion, a thin layer of pure aluminum 2S is bonded to each side of the sheet. This pure aluminum coating has a yery high re- sistance to direct contact with corrosive agents and also, Dy electrolytic action, it serves to protect the cut edges of the sheet. The material is slightly inferior in strength to 24S0 aluminum alloy, but it possesses excellent forming qualities. Parts requiring severe work- ing and bending should be formed of 24S0 alclad and then heat treated to the full hardness of 24ST. RESTRICTED [18] RESTRICTED GENERAL PAR. 35 TO 37 35. ALUMINUM SHEET, 2^ST ALCLAD. The heat-treated form of 24S0 ale lad is known as 24ST. This material is the most generally used of al I the aluminum a I loys and is uti I I zed for ribs, frames, spars, longerons, stringers, skin, and formers. Although slightly inferior to 24ST aluminum alloy in strength, 24ST ale lad possesses far greater corrosion resistance. On each face of the high-strength 24ST core is an integrally bonded layer of relatively high purity aluminum known as the coating. (See Figure 26.) This coating protects the core in two ways. It protects the core elect rolyt ical ly and covers the core to prevent contact with corrosive agents. The material should never be fully annea I ed . 36. HEAT TREATING ALUMINUM, 24S0. The heat treating of 24S0 aluminum or 24S0 alclad should be accomplished in either an air furnace or salt bath furnace. Methods of treat- ment in which the flame may come in direct con- tact with the material are not recommended. The heat-treating process consists essentially of: ( I) heating the material to a prescribed tem- perature; (2) holding the material at this tem- perature for a specified length of time; (3) promptly quenching the material; and (4) allow- ing the material to age harden at room tempera- ture for a specified period. The actual heat- treating temperature of 24S0 aluminum and 24S0 alclad must remain constant within a range of 4g\-4gq°C (9I5-930°F) for the time specified on the following charts. However, periods specified should be timed after the charge has reached uniform heat-treating temperatures throughout the furnace. AJso, when heat treat- ing parts of varied thickness simultaneously, use the thickest sheet as a timing criterion. For example, when heat treating a sheet of .040- in. and a sheet of .064^ in. use a minimum heat-treating time of 30 minutes and maximum heat-treating time of 40 minutes. AIR FURNACE METHOD SALT BATH METHOD MATERIAL GENERAL PAR. 37 TO ^0 RESTRICTED (due to the quenching) should not cause re- jection if the part can De properly straightened during assembly or within one hour after quench- ing. In fact, if any rework is necessary, it is advisable to accomplish it always within one hour after quenching before the aging has progressed too far. During this period, the metal may be worked with ease and without dan- ger of cracking. Aging may be retarded by placing the material in a cold atmosphere. 38. AGE HARDENING. After quenching, the strength of the 24S aluminum or 24S aid ad gradual ly increases at room temperature until, after approximately 24 hours aging, the material reaches a fully hardened condition. When this occurs, the material is ready for installation. 39. ANNEALING ALUMINUM, 24ST. When annealed 24S or 24S a I c I ad materials are required in the course of repair, they should be obtained in the annealed condition /VAA STANDARD ALCOA DIE NO. PRINCIPAL DIMENSIONS from the metal manufacturer. However, if 24S0 material is not available, it is sometimes per- missible to anneal 24ST aluminum al loy fully and to anneal 24ST alclad partially. However, this is not recommended where the material is to be used in location of high stress. Of the temperature range specified for anneal ing 24ST aluminum a I loy, the lower temperature (343°C, 650°F) will anneal the material sufficiently to permit removal of cofd-working strains as required for al I ordinary types of repair fab- rication. The upper temperature (427°C, 800°F) specified below for 24ST aluminum al loy wi II permit maximum annealing; however, the material must be held at this temperature for two hours, then cooled to 260°C (500°F) at the rate of IO°C (50°F) per hour. After the temperature of aluminum alloy has reached 260°C (500°F), the cooling rate in air is not critical. It is to be noted that the temperature range spec- ified below for 24ST alclad wi I I only part iai ly anneal the material. Full annealing of 24ST alclad is not permitted, because of the rapid diffusion of the base metal through the aluminum coating occurring as a result of slow cool ihg from high temperatures. The following chart specifies annealing temperature particulars applicable to air furnace and salt bath furnace. ALLOY ANNEALING TEMPERATURE C366T L249I0 C373LT NONE (ROLLED ALCLAD) K77A K77A -75 .125 -1 Figure 29^Extrusion Equivalent Chart 24ST AL. ALLOY 24ST ALCLAD 343-427 338-349 650-800 640-660 40. BENDING 24S ALCLAD. Exercise caution in handling alclad materials to avoid scratching through the pure aluminum coating. Besides destroying the protective aluminum coating, scratches in alclad material are potential cracks which may develop under the application of stress. Where the material must be flanged, a power or hand brake will be found particularly useful. Alclad sheet may be formed and bent as required, but the allow- able bend radius for the thickness of sheet, as specified herein, should not be exceeded. The following chart specifies particulars per- tinent to the bending of alclad. ALCLAD 24ST 2US0 ALLOWABLE BEND RADIUS 4 TIMES THE THICKNESS OF THE SHEET OR GREATER. 2 TIMES THE THICKNESS OF THE SHEET OR GREATER. RESTRICTED [20]