SERVICE KIT. February 8, 1980 Revision C - April 16, 1999 Page 1 of 24

Transcription

1 , TITLE WING FRONT SPAR LOWER CAP MODIFICATION EFFECTIVITY MODEL YEAR SERIAL NUMBERS / thru A A0001 thru 401A B 1970/ B0001 thru 401B B B0122 thru 401B / thru A A0001 thru 402A B 1970/ B0001 thru 402B B B0201 thru 402B B B0301 thru 402B B B0501 thru 402B B B0801 thru 402B B B1001 thru 402B B B1201 thru 402B B B1301 thru 402B1384 DESCRIPTION The following procedures provide instructions to install external doublers and straps on lower surface of the wing front spar. APPROVAL FAA approval has been obtained on technical data in this publication that affects airplane type design. REFERENCE MEB79-16 CHANGE IN WEIGHT AND BALANCE MODEL , 402 WEIGHT INCREASE Pounds ARM Inches RESULTANT MOMENT Inch-Pounds MOMENT/ Multi-engine February 8, 1980 Revision C - April 16, 1999 Page 1 of 24 To obtain satisfactory results, procedures specified in this publication must be accomplished in accordance with accepted methods and prevailing government regulations. The Cessna Aircraft Company cannot be responsible for the quality of work performed in accomplishing the requirements of this publication. The Cessna Aircraft Company, Product Support, P.O. Box 7706, Wichita, Kansas 67277, U.S.A. (316) , Facsimile (316) COPYRIGHT 1980

2 MATERIAL INFORMATION Page 2 PART NUMBER QUANTITY DESCRIPTION SK402-36B 1 Kit, Consisting of the folllowing parts: AN3H11A 8 Bolt AN4-10A 8 Bolt CM S 2 Plug Button HL18PB Hi-Lok HL19PB Hi-Lok HL19PB Hi-Lok HL Collar HL Collar MS20601AD4W2 20 Rivet MS20601AD5W2 2 Rivet MS21042L08 28 Nut MS21044C3 16 Nut MS21044C4 8 Nut MS21069L08 4 Nut MS24694S13 28 Screw MS Screw NAS1149F0363P 24 Washer NAS1149F0463P 16 Washer NAS1149FN832P 28 Washer NAS1738B Rivet NAS1738B5-2 4 Rivet NAS1738B5-4 4 Rivet NAS1738M Rivet NAS1738M Rivet NAS1739B4-4 3 Rivet NAS1739B4-6 2 Rivet NAS1739B4-7 6 Rivet NAS1739B4-8 4 Rivet NAS1739B5-2 4 Rivet NAS1739B Rivet Drawing, Sheet 1 of 2 and Sheet 2 of 2 Modification, Wing Structure, Front Spar

3 Page 3 In addition to the parts furnished in this kit, the following will be required for this modification. PART NUMBER QUANTITY DESCRIPTION MIL-S-8802IIB2 2 Sealant (Semkit, 6 oz.) CMNP009 (or equivalent) 2 pt Firewall Sealant (alternate is Pro-Seal 700) PART NUMBER QUANTITY DESCRIPTION Angle Assembly Filler Doubler Doubler Doubler Strap Firewall Segment - Left Firewall Segment - Right 1 Instructions

4 TOOLING Page 4 The following equipment was used to develop this procedure. Equivalent substitutes may be used if necessary. PART NUMBER QUANTITY DESCRIPTION ED Centurian NDT Corp 404 Remington Rd. Suite 107 Chaumburg, IL HS.156 with split stem and collar Absolute coil KHz 1 BOLT HOLE PROBE UniWest 330 West Clark Pasco, WA Phone HS.187 with split stem and collar 1 BOLT HOLE PROBE UniWest 330 West Clark Pasco, WA Phone HS.250 with split stem and collar 1 BOLT HOLE PROBE UniWest 330 West Clark Pasco, WA Phone Coupon Assembly Cessna Aircraft Co. P.O. Box 7704 Wichita, KS Phone

5 ACCOMPLISHMENT INSTRUCTIONS. This service kit modifies the front spar by installing a doubler and strap on the front spar lower cap horizontal flange, extending from the wing root fitting outboard, to just past the engine beams. These instructions do not include complete step by step procedures and must be used in conjunction with Cessna modification drawing (latest revision) included with this kit during the performance of this modification. Due to varying length requirements, all driven type rivets have been omitted from this kit. The modification drawing should be referenced for rivet diameters and each hole should be checked individually for length requirements. All Refer to Zone references used in the instructions of this service kit are the zone locations noted on the modification drawing. Step 7 of these procedures provides information regarding the fastener codes used on the modification drawing and to assist in determining the proper hole size requirements. Illustrations showing various stages of the modification have been attached to these procedures for use as a reference. 1. Preparation WARNING: OBSERVE ALL FUEL SYSTEM FIRE AND SAFETY PRACTICES. A. Defuel the airplane of all fuel from the wing, tip tanks, and wing auxiliary (locker) tanks in accordance with procedures outlined in the Service Manual. B. Place airplane on jacks in accordance with the Service Manual procedures. Remove the wing gap panels around the wing root area of the left and right wings. Retain all hardware for reinstallation. C. Place a jack under the forward wing attach fitting (using wood blocks to prevent damage), left and right wings. Raise the airplane enough so that the jacks are supporting the fuselage weight. Use engine hoists to relieve weight from the engine beams. D. Place a tail stand under the tail section of the airplane. E. Place a jack outboard of under the front spar lower cap (using wood blocks to prevent damage) to support the outer most weight of the wings. Supporting of the left and right wings during this modification is very important. The wings must be supported in a relaxed state (removal of all fuselage weight). There will be a large number of rivets removed from the front spar lower cap. Each wing must be secure and not moved during the modification so that the rivet holes through the lower spar cap will not shift. 2. Component removal A. Remove all engine cowlings from left and right engine. (Refer to applicable sections of the Service Manual.) B. Remove the following items from the forward portion of the firewall and aft of the canted bulkhead of the left and right engine compartment: turbocharger heat shield, turbocharger exhaust stack, air filter, turbocharger, waste gate, turbocharger mount, and all lines and hoses forward of the firewall. Retain all hardware for reinstallation. (Refer to applicable sections of the Service Manual.) C. Remove the firewall access door, retain hardware for reinstallation. D. Disconnect and lower the outboard left and right landing gear doors. (Refer to applicable sections of the Service Manual.) Page 5

6 E. Disconnect and remove the outboard landing gear drive tube assembly that is connected between the idler bellcrank and torque tube assembly. Retain all hardware for reinstallation. (Refer to applicable sections of the Service Manual.) F. Remove rivets that secure the left and right lower aft nacelle skin panels as required to provide easy access to the lower front spar cap. (See step G for fastener removal procedures.) CAUTION: DO NOT OVERSIZE HOLES WHEN REMOVING FASTENERS. G. Fastener removal. The following instructions describe typical fastener removal procedures. Fastener removal procedures are detailed here to emphasize the necessity for exercising extreme care during fastener removal in order to minimize the possibility of damaging the holes in the spar caps or compounding existing damage in the spar cap holes. The primary focus of this modification is to improve the fatigue life of the spar cap, and the spar cap holes are of critical importance. (1) Remove Hi-Lok fasteners by removing the collar or by breaking the collar with a chisel. (2) For driven rivets, center punch the center of each fastener head. CAUTION: DO NOT DRILL THRU WING STRUCTURE WHEN REMOVING FASTENERS. (3) Use the following drill bit and drill stop setups for the specified size fasteners: (a) For 5/32 inch diameter driven rivets, use a number 30 (0.128 inch diameter) drill bit with a drill stop set to 0.06 inch. (b) For 1/8 inch diameter rivets, use a number 40 (0.098 inch diameter) drill bit with a drill stop set to 0.04 inch. Use a narrow or tapered drill stop to maintain visibility of the work. Drill stop settings are along the full diameter of the drill bit, and do not include the apex of the drill bit. CAUTION: DO NOT DRILL INTO THE SHANK OF THE FASTENER. (4) Using the appropriate drill bit with the drill stop installed, drill into the head of the fastener. (5) Insert a drift punch into the hole and break off the fastener head by exerting side pressure on the drift punch. (6) Check the clearance above each fastener before driving it out. Do not drive a fastener into structure inside the wing. CAUTION: DO NOT ALLOW THE DRIFT PUNCH RIVET SET TO SLIP OFF THE FASTENER WHILE DRIVING. DAMAGE TO THE WING SKIN WILL RESULT. (7) Using a drift punch set in a rivet gun, drive the shank out of the hole. This method will assist in breaking the sealant cleanly around the tail of the fastener. If a drift punch set is not available, place a drift punch on the remaining shank and drive it out by tapping on the punch with a hammer. Page 6

7 H. Engine lower firewall removal. (1) In order to gain access to the upper portion of the forward lower spar cap, a portion of the engine nacelle firewall must be removed; modify as follows: CAUTION: Use extreme care when drilling in firewall area to prevent drilling into the spar, fuel lines or wire bundles located immediately aft of the firewall. (a) (Refer to Zone 15-B and 17-B.) Remove rivets that secure doublers and angles, left and right, to the support assemblies. (b) (Refer to Zone 15-B and 17-B.) Remove left, right, left, right angles from the lower portion of the engine nacelle firewall. (c) (Refer to Zone 16-B.) Remove angle from the lower portion of the left and right engine nacelle firewall. (d) (Refer to Zone 15-B to 17-B.) Cut out and trim the lower portion of the firewall in accordance with dimensions shown. (e) Break and smooth all sharp edges around the existing firewall skin. 3. Lower front wing spar cap modification/fastner hole inspection, left and right. CAUTION: WHEN REMOVING RIVETS, DRILL OFF THE HEADS OF THE RIVETS USING THE PROPER SIZE DRILL BIT. DRIVE THE SHANK THROUGH THE SPAR USING A PIN PUNCH OF THE CORRECT SIZE. DO NOT DRILL RIVETS OUT AT LOCATIONS THAT ARE CODED WITH FLAG NOTE 4. SEE MODIFICATION NOTES ON DRAWING , SHEET 2, FOR ALL OTHER NOTES. A. Remove the grommets at approximately (Zone 4-C), (Zone 5-C) and at (Zone 9-C) from the lower wing skin. Retain grommets. B. (Refer to Zone 5-A and 6-A.) Remove the MS20470AD6 rivets in the lower spar cap and web from to C. (Refer to Zone 8-A and 8-C.) Remove rivets, bolts, and screws at that attach the angles to the support assemblies along the lower spar cap. Retain angles for reinstallation and discard bolts and screws. D. (Refer to Zone 7-C and 8-C.) Remove bolts at and that secure the support assemblies to the lower spar cap. Discard bolts. E. (Refer to Zone 4-C through 10-C.) Remove rivets through the lower front spar cap from to approximately , (Refer to drawing, Sheet 1, for rivets to be removed.) CAUTION: USE EXTREME CARE WHEN REMOVING AND INSTALLING FASTENERS ON AFT SIDE OF SPAR, BETWEEN AND , TO AVOID DAMAGE TO THE AUXILIARY FUEL TANK FLOOR IF THE AIRPLANE HAS AUXILIARY TANKS INSTALLED. F. (Refer to Zone 5-D, Detail G.) Rework the left and right support assemblies as shown in order to install the strap, typical left and right engines. G. (Refer to Zone 10-A, Detail H.) Rework the support assemblies at by removing material, as shown. Remove the large access cover on the upper wing skin outboard of the nacelle in order to facilitate installation of fasteners in the lower front spar cap. Retain cover and hardware. Page 7

8 H. (Refer to Figure 3.) Eddy current inspection of lower cap. An eddy current inspection in accordance with the following procedures must be performed on all holes in the lower forward spar cap prior to the straps being drilled and fitted for installation. Only those holes in the spar cap common to the straps will require inspection. Cracks detected during this inspection must be reported to Cessna Product Support along with the following information: hole diameter, location of hole, hole edge distance, length and direction of crack, for disposition. I. Inspection. (1) Prior to the inspection, and after removal of rivets, check the wing skin and web for any excessive gap between skin and spar. To eliminate any gap, use temporary sheet metal fasteners to hold skin in contact with the spar during inspection. (2) Clean fastener holes using solvent and a nonmetallic brush or cotton swab to remove grease, dirt, metallic chips, etc. (3) Adjust probe depth to 0.07 inch from collar to center of coil. Standardize the eddy current instrument for balance and lift-off in accordance with the manufacturer s operator handbook, using coupon assembly with probe inserted from notched surface, and with coil away from notched side of hole. Make final lift-off adjustment by pushing coil away from side of fastener hole. Meter should read the same when coil is in contact or away from side of hole. Adjust sensitivity to induce 100 ± 10 micro amperes deflection when coil is rotated past notch. (Down scale deflection on Model ED 520.) J. Probe Depth settings: (1) Spar cap fastener holes inches. (2) Spar vertical flange inches. K. Scan each fastener hole with a full 360 scan. Rotate probe slowly while observing the meter readings. Pay particular attention to the critical areas of the holes. Critical area for spar cap holes is in the forward and aft direction. The vertical flange is in the vertical direction (up and down). If probe passes over a crack, the meter needle will deflect rapidly and return to approximately the original reading. Carefully repeat the inspection in the opposite direction to verify the crack indication. Gradual meter needle movement up or down scale may occur due to slightly out of round holes or minor changes in the conductivity of the material. L. Remove the , , and doublers and transfer the holes to the strap. An alternate method for locating holes in strap is to obtain a 1/4 inch piece of clear plexiglass approximately 4 inches wide and length of strap. Transfer holes thru drilled out spar cap thru the plexiglass. Using plexiglass as a template, transfer and drill holes thru strap. M. Place the strap, , , and doublers back on the lower front spar cap. Secure wtih temporary sheet metal fasteners. N. Place the , , and doublers, one at a time, over the holes drilled out in the lower front spar cap. Using an undersize drill bit, and hole finder, locate holes in the doublers to match holes in the spar. When drilling holes in the , , and doublers to match holes in the lower front spar cap, allow the drill to follow the existing alignment of the holes in the spar, so as not to elongate the existing holes in the spar. This is important as some of the holes may not be drilled perpendicular to the spar cap. Page 8

9 O. Enlarge holes through the lower strap and , , and doublers to the correct diameter. Refer to Cessna Drawing and the fastener code hole size chart at the conclusion of these procedures to determine the proper hole diameters. Holes requiring installation of HL18PB and HL19PB fasteners must be drilled and reamed to the dimensions specified in the fastener codes of these procedures on page 14. P. (Refer to Zone 7-D and 8-D.) Locate the angle assembly in the left and right support assemblies. Q. (Refer to Zones 8-C and 9-C, View D-D.) Locate the angle (retained from step 3.C.) and filler at against the support assemblies. Drill four (4) each and inch diameter holes through angle and strap, to match existing holes in the lower front spar cap. R. (Refer to Zones 8-A, 8-D and 9-D.) Position the angle assembly in the support assembly until they firmly contact the sidewalls of the support assemblies. At this time, the holes shown in Zone 8-D should be drilled in the trough of the angle assemblies (through the angles only and not into the strap). S. (Refer to Zones 7-A and 8-D.) Drill two (2) inch diameter holes through the angle assembly and through the lower spar strap to match existing holes in the lower front spar at and at 98.74, typical left and right wings. T. (Refer to Zones 4-C, 5-C and 9-C.) Drill new inch diameter holes (3 required on each wing) for installation of the grommets, as shown on the drawing. U. (Refer to Zones 9-C.) Install the CM S plug button, as shown. V. Remove the , , and doublers and the strap from the lower front cap and deburr all holes. 4. Lower front spar strap and doubler installation. A. Reinstall , , and doublers, and strap on the lower front spar cap. Secure with temporary sheet metal fasteners. B. Secure the strap, , , and doublers to the lower front spar cap. (Refer to Zone 13A and to the hole size table on page 14 for fastener information.) C. (Refer to Zones 7-D and 8-D.) Temporarily install the angle assemblies in the support assemblies using temporary sheet metal fasteners in the two (2) 3/16 inch diameter holes. Lay out and drill specified holes through the side flanges. D. Remove the angle assemblies at completion of drilling and deburr all holes. E. (Refer to Zones 7-A and 8-A.) Secure the angle assembly in the support assemblies. Use AN3H-11A Bolts, MS21044C3 Nuts and NAS1149F0363P washers, as required, to secure angle to the lower, front spar. (Refer to Zone 13A, and the hole size table for clarification of fasteners to be installed in the angle assemblies and support assemblies.) Do not install HI-LOK fasteners in the forward part of the angle assembly at this time (to be installed in step 5E). Page 9

10 F. Install angles and filler at Secure angles to the lower, front spar cap using hardware called out in Zone 8-A. Rivet the angles and filler to the support assemblies. (Refer to Zone 13A and the hole size table for rivet code clarification of fasteners to be installed.) 5. Lower firewall segment installation. A. (Refer to Zone 16-B to 17-B.) Retrim the and firewall segments, supplied in this Service Kit, to dimension shown on drawing, to match existing nacelle firewall. B. Install the and firewall segments. (Refer to Zone 14-B and the holes size table for fastener information.) C. (Refer to Zones 15-B, 17-B and Zone 6-A.) Trim the , , , and angles so that there is approximately 0.10 inch gap between the top of the angles and the strap. Install angles onto the and firewall segments. (Refer to Zone 13A, and the hole size table for fastener information.) Cut off the tab on the and -9 angles. (Refer to flag note 18 on drawing.) D. (Refer to Zone 16-B.) Install angle in the lower center portion of the firewall segment. E. (Refer to Zone 16-B and 17-B.) Rivet the doublers, and angles to the firewall segment. Secure the doubler and angle assemblies to the support assemblies using HI-LOK fasteners called out in Zone 7-D. Do not drill the top pilot holes in the doublers as they might interfere with the top radius of the or angles. Locate holes farther down the doublers, as required. F. (Refer to Zones 16-B and 17-B.) Fay seal the angles using Pro-Seal 700 sealant, or equivalent and install on the top of the support assemblies. (Refer to Zone 13A and the holes size table for fastener information.) G. When all rivets are installed in the and firewall segments, seal all joints, seams and cracks in the firewall using Pro-Seal 700 sealant, or equivalent. Refer to note on page Components reinstallation. A. Reinstall the firewall access door, using the existing screws and Pro-Seal 700 sealant, or equivalent. B. Reinstall all components removed from the left and right engine compartments. Install new hardware, as required. ( Refer to applicable sections of the Service Manual.) C. Reinstall the lower nacelle skins to the wing. Trim skins, if required, to clear the strap. D. Connect the outboard main landing gear drive tube assembly to the idler bellcrank and torque tube assembly. (Refer to applicable sections of the Service Manual.) E. Perform a landing gear rigging check in accordance with the Service Manual. F. Reconnect the lower, inboard landing gear doors. G. Remove tail stand from under airplane tail section. H. Remove jacks from the forward attach fittings and from outboard of the engine nacelles. Reinstall wing gap fairing on the left and right wings. I. Paint the lower front spar cap as required to match the color of the airplane in accordance with the Service Manual. J. Make an entry in the airplane logbook stating this service kit has been installed. Page 10

11 7. Fastener symbols and codes. A. The symbol includes a single cross whose intersection is at the location of the fastener. When space does not permit, the symbol may be located adjacent to the area. (1) Fastener identity, size, installation requirements, etc., shall be indicated by a letter-numeric coding within the quadrants of the symbol (cross). (2) Quadrant orientation of the symbol is determined by the direction of the letter-numeric coding as written within the symbol. When the symbol is viewed in a position such that the letters are upright, the upper Left quadrant is NW, etc. The following examples illustrate the basic symbol and quadrant identity. (a) Northwest (NW) Quadrant. 1 The identity of the fastener is shown in the NW quadrant by a letter code. The code is made up of letters and defines all features of the fasteners except diameter and grip. An example of the symbol and fastener code. (b) Northeast (NE) Quadrant. 1 Fastener diameter and location of the manufactured head is shown in the NE Quadrant by a numeric letter code. The fastener diameter is shown by a number which is the dash number that represents the diameter in the full part number. If the diameter is designated by digits of the basic part number, then the significant digits shall be shown. The location of the manufactured head of the fastener is defined by the code letter F for far-side and N for near-side. When the location of the manufactured head is insignificant, the code letter may be omitted. An example of the symbol, fastener diameter and location of manufactured head. (c) Southeast (SE) Quadrant 1 The length and permission to spot weld as an alternate assembly method is shown in the SE quadrant by a numeric-letter code. 2 The length is shown by a number which is the dash number that represents the length in the full part number. 3 Engineering permission to spot weld in lieu of using the fastener called for is denoted by the letter W. Page 11 NE NW SE SW BJ 4F 4N

12 4 The preceding data is an option feature of the code, but the use of any alternate method of designating the preceding data within the symbol is not optional. An example of the symbol, fastener length and spot weld alternate. (d) Southwest (SW) Quadrant. 1 Dimple and countersink data - The sheets to be dimpled or countersunk are shown in the SW quadrant by a numeric-letter code as defined below, not to exceed three digits per line. Unless otherwise noted, the normal angle for the dimple or countersink shall be the same as the angle of the manufactured rivet head. a The letter D is used to show dimpling (form of countersinking) operation and when more than one sheet is dimpled a number follows the D to show how many sheets are dimpled. b The letter C is used to show countersinking operation. No number is used after the countersinking designation because it is the responsibility of the individual to see that the thickness of material to be countersunk for a flush condition will not violate structural requirements. Example: c Protruding head rivets to be upset flush may be indicated by placing the numeric letter code on the first line which indicates the dimple or countersink operation for the upset end. The second line indicates the nominal angle for the upset end. Example: d The flush both sides condition may be indicated by placing the numericletter code on separate lines where: First line - The first line indicates the dimple or countersunk operation for the manufactured head. Second line - The second line indicates the dimple or countersink operation for the upset end. Third line - The third line indicates the nominal angle for the upset end when different from the angle of the manufactured head. Examples: Page 12 W 5W 5 D3C C D2 DC C 100 C 82 C DC D2C C DC DC D2C C 82

13 Optional - Optional when the dimple-countersink operation for the double flush rivets are controlled by applicable company requirements, the instruction to double flush may be indicated by noting the angle of the manufactured head on the first line and the angle of the upset end on the second line. Examples: (2) The use of the dimple-countersink feature of the symbol is optional. Any alternate method of designating the dimple-countersink feature for the flush one or both sides within the symbol is not optional. 8. Examples. A. Description of Typical Symbols. (1) MS20470AD4 Rivet, Universal Head (head direction is not shown - assumed to be insignificant. (2) MS20426AD4 Rivet, 100 Countersunk Head (head location not shown - assumed to be obvious in this case; since there is always a reason for using countersunk rivets, the head location of this type can never be insignificant). (3) MS20426AD4 Rivet, 100 Countersunk Head (manufactured head to be located on the near side). (4) MS20426AD4 Rivet, 100 Countersunk Head. First and second sheets adjacent to manufactured head to be dimpled, remainder of sheets to be countersunk. The location of the manufactured head is assumed to be obvious from the illustration in this case. (5) NAS1468 Lockbolt - Protruding Head, Close Tolerance Shank, including NAS1080 collar. The location of the manufactured head is assumed to be insignificant or obvious in this case. Page 13 4 BJ 4 BB 4N BB D2C 4 BB 5 8 DT

14 (a) For Flush Upset End on Protruding Head Rivet. 1st Line - Dimple or Countersink 2nd Line - Nominal Upset Angle (b) Flush Both Sides. 1st Line - Manufactured Head Dimple or Countersink 2nd Line - Upset Head Dimple or Countersink 3rd Line - Upset Head Angle, Different Manufactured Head (c) Flush Both Sides Optional. 1st Line - Nominal Angle of Manufactured Head 2nd Line - Nominal Angle of Upset Head Rivet symbols are used on the drawing only at the beginning and ending of each series of rivets. This signifies that all rivets between these two symbols will be the same as those specified in the beginning and ending symbols. * Standard hole sizes for these fasteners are #40 drill for size 3/32 inch diameter rivets, #30 drill for size 4/32 (1/8) inch diameter rivets and #21 size 5/32 inch diameter rivets. Page 14 Basic Code Dash Number for Diameter (1/32 s) N = Manufactured Head Near Side F = Manufactured Head Far Side D = Dimple Figure = Number of Sheets to be Dimpled C = Countersunk (For Special Flush Conditions Only, See Notes a, b and c) Dash Number for Length W = Spotweld Optional RIVET CODE PART NUMBER HOLE SIZE BJ MS20470AD * STANDARD BB MS20426AD * STANDARD AAO NAS1738B (#27 DRILL) NAS1738B (#16 DRILL) NAS1738B (# 5 DRILL) WY HL19PB HL19PB LZ NAS1097AD * STANDARD LN MS20615M * STANDARD AAT NAS1739B (#27 DRILL) NAS1739B (#16 DRILL) AAR NAS1738M (#27 DRILL) YA HL18PB

15 Page Figure 1. Eddy Current Reference Standard CALIBRATION NOTCHES ARE LOCATED IN THE CENTER FASTENER FOR EACH TYPE. CALIBRATION AREA COUPON ASSEMBLY (REFERENCE)

16 Page 16 Figure 2. Lower Front Wing Spar Cap Modification (Sheet 1 of 3) NACELLE SKIN REMOVAL REQUIRED TO GAIN ACCESS TO WORK AREA (STEP 2.F OF PROCEDURES) CUTOUT THROUGH SUPPORT ASSEMBLY (STEP 3.G. OF PROCEDURES) STRAP (1 REQUIRED) SKIN REMOVAL (VIEW LOOKING INBOARD - LEFT NACELLE) STRAP INSTALLATION (VIEW LOOKING UP - LEFT NACELLE) FWD FWD UP INBD

17 Page 17 EXISTING FIREWALL TRIM LINE (STEP 2.H OF PROCEDURES) EXISTING FIREWALL WITH LOWER SECTION CUT AWAY (STEP 2.H. OF PROCEDURES) ENGINE NACELLE FIREWALL (VIEW LOOKING DOWN AND AFT - LEFT WING) ENGINE NACELLE FIREWALL CUTOUT (VIEW LOOKING DOWN AND AFT - LEFT WING) UP INBD UP INBD Figure 2. Lower Front Wing Spar Cap Modification (Sheet 2)

18 Page 18 Figure 2. Lower Front Wing Spar Cap Modification (Sheet 3) OR FIREWALL SEGMENTS (1 EACH REQUIRED) (STEPS 5.A THROUGH 5.G OF PROCEDURES) DOUBLER ANGLE (1 REQUIRED) SEE ZONE 7-D OF MODIFICATION DRAWING FOR HI-LOK FASTENER INSTALLATION AND ANGLE INSTALLATION (STEP 5.E. OF THE PROCEDURES) FIREWALL SEGMENT INSTALLATION (VIEW LOOKING DOWN AND AFT - LEFT WING) AND ANGLE INSTALLATION (VIEW LOOKING UP - LEFT WING) FWD INBD UP INBD

19 Page Figure 3. Lower Front Wing Spar Cap Fastener Hole Inspection (Sheet 1 of 6) FWD INBD VIEW LOOKING UP AT LEFT WING

20 Page Figure 3. Lower Front Wing Spar Cap Fastener Hole Inspection (Sheet 2) FWD INBD VIEW LOOKING UP AT LEFT WING

21 Page Figure 3. Lower Front Wing Spar Cap Fastener Hole Inspection (Sheet 3) FWD INBD VIEW LOOKING UP AT LEFT WING OUTBOARD ENGINE BEAM (REFERENCE)

22 Page Figure 3. Lower Front Wing Spar Cap Fastener Hole Inspection (Sheet 4) FWD INBD VIEW LOOKING UP AT LEFT WING OUTBOARD ENGINE BEAM (REFERENCE) INBOARD ENGINE BEAM (REFERENCE)

23 Page Figure 3. Lower Front Wing Spar Cap Fastener Hole Inspection (Sheet 5) FWD INBD VIEW LOOKING UP AT LEFT WING INBOARD ENGINE BEAM (REFERENCE)

24 Page Figure 3. Lower Front Wing Spar Cap Fastener Hole Inspection (Sheet 6) FWD INBD VIEW LOOKING UP AT LEFT WING ROOT RIB (REFERENCE)