SERVICE BULLETIN M20-316

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MOONEY AVIATION COMPANY, INC. SERVICE BULLETIN 165 Al Mooney Road North Kerrville, Texas 78028 SERVICE BULLETIN M20-316 Date: November 15, 2012 THIS BULLETIN IS FAA APPROVED FOR ENGINEERING DESIGN MOONEY AVIATION COMPANY, INC. 165 Al Mooney Road North, Kerrville, Texas 78028 tel: 830-896-6000 www.mooney.com Page 1 of 5 SUBJECT: M20TN ENGINE ISOLATOR MOUNT INSPECTION MODELS/ SN M20TN - 31-0002 thru 31-0023 and 31-0025 thru 31-0127 AFFECTED: TIME OF INITIAL INSPECTION WITHIN 10 FLIGHT HOURS / NEXT 100 HR INSPECTION COMPLIANCE: INTRODUCTION: There has been a report from the field of improper clamp-up and distortion of the mount isolat- ors, as well as extreme difficulty in the re-installation in general. Both the service manual and illustrated parts catalog incorrectly identified the mounting sequence (refer to Mooney Ser- vice Instruction M20-121) and will be updated at their next revision cycle to reflect this inform- ation. Because the exact history of this installation is unknown, an inspection is required for field M20TN's to verify engine installation. INSTRUCTIONS: Read entire procedures before beginning work. STEP 1 - Initial Inspection 1.1. Turn master switch - OFF. 1.2. Inspect area of cowl around propeller shaft for evidence of interference and/or movement of the propeller shaft against the cowling. 1.3. Remove top cowling, refer to MAC Service and Maintenance Manual. 1.4. Inspect top cowling around propeller shaft area and inside upper area for chaffing, scuffing or interference “witness marks”. 1.5. If no problems are found. Replace and secure top cowling. Make Log Book entry that "Step 1 of Service Bulletin M20-316 was performed on (Date & TT). No engine Movement indicated. Return to Service". At next 100 Hr Inspection, perform STEP 2 of this service bulletin. 1.6. If chaffing, scuffing or interference “witness marks”have been found - continue to next steps of this service bulletin. 1.7. Remove bottom cowling, refer to MAC Service and Maintenance Manual. 1.8. Check the bottom of all engine isolator halves (4 qty) for any movement or looseness. Determine cause of wear/witness marks. Clear the interference as required. 1.9. If no movement is present - torque all 4 bolts to 450-500 in. lbs. (refer to MAC Service and Maintenance Manual). Reinstall bottom and top cowl. Make Log Book entry that "Step 1 of Service Bulletin M20-316 performed on (Date & TT). Verified security of Isolator mounts. Cleared interference to cowl. Return to Service". At next 100 Hr Inspection, perform STEP 2 of this service bulletin. 1.10. If movement has been determined, continue to next steps of this service bulletin. 1.11. Refer to STEP 2 and remove each isolator (one at a time), verify correct and/or stack-up as shown in Figure SB M20-316-1 (Refer to MAC Service Instruction M20-121). NOTE: The arrangement of engine isolator mounts is extremely critical. Make certain they are arranged as shown in Figure SB M20-316-1. STEP 2 - Annual Inspection and/or Replacing Engine Isolators: 2.1. Turn master switch - OFF. 2.2. Remove top and bottom cowling, refer to M20TN Service and Maintenance Manual. 2.3. Support the engine using an “A” Frame with chain hoist or hydraulic “Cherry Picker” and hook into the front and rear engine lifting hooks, refer to M20TN Service and Maintenance Manual. MOONEY AVIATION COMPANY, INC. SERVICE BULLETIN 165 Al Mooney Road North Kerrville, Texas 78028 SERVICE BULLETIN M20-316 Date: November 15, 2012 THIS BULLETIN IS FAA APPROVED FOR ENGINEERING DESIGN MOONEY AVIATION COMPANY, INC. 165 Al Mooney Road North, Kerrville, Texas 78028 tel: 830-896-6000 www.mooney.com Page 2 of 5 2.4. Remove or disconnect any components that prevent lifting engine slightly to remove engine isolator mounts. 2.5. Remove all four (4) retaining bolts, washers, heat shields and lower isolators at all four locations. Keep heat shield and mounting hardware 2.6. Lift engine to allow removal of all four upper engine isolator mounts and hardware. 2.7. Inspect Heli-Coils in engine legs for any damage i.e., cross-threading. Replace legs as required. NOTE: The arrangement of engine isolator mounts is extremely critical. Make certain they are arranged as shown in Figure SB M20-316-1. 2.8. Use “dummy” bolts (NAS6607-15 or equivalent) and washers to secure each of the upper halves of isolator mounts. Ensure upper washer and heat shield are installed between isolator and engine motor mount castings (4 places). Tighten bolts to compress rubber mounts to approximate thickness shown in Figure SB M20-316-2. 2.9. Before lowering engine, lube all four mount cups with silicone lubricant to help facilitate alignment. 2.10. Slowly lower engine into motor mount cradle. Support weight of engine with lift until engine is properly placed in mount. When engine is first lowered, the isolator mounts will not rest squarely in the cups on the mount refer to Figure 2. Seat both rear mounts first, then front left & right mounts. 2.11. Use a large flat screwdriver to pry mounts into cups. This step requires a considerable amount of patience and “elbow grease” - refer to Figure SB M20-316-2. 2.12. Once top engine mounts are all seated in the cups, begin removing “dummy” bolts and washers. Start at right rear (RR), then left rear (LR), left front (LF), and right front (RF). NOTE: Keep bolt and washer centered in the cup to prevent binding and stripping of threads. 2.13. Correctly position each heat shield in place per figure 1, index drain holes at lowest point of installation & index cutouts parallel to sides of engine mount. Make sure heat shields are oriented to prevent chaffing or interference on engine mount or engine components. 2.14. Install both retaining bolts, washers and torque to specification - refer to Figure SB M20-316-1. 2.15. Reinstall top and bottom cowling, refer to MAC Service and Maintenance Manual. 2.16. Complete log book entry. NOTE: