AD 87-18-12 R1
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | MD Helicopters, Inc. | 369D | Airworthiness Directives; McDONNELL DOUGLAS HELICOPTER COMPANY (MDHC) (Hughes Helicopter, Inc.) Model 369D, 369E, 369F, and 369FF Helicopters |
| aircraft | MD Helicopters, Inc. | 369E | Airworthiness Directives; McDONNELL DOUGLAS HELICOPTER COMPANY (MDHC) (Hughes Helicopter, Inc.) Model 369D, 369E, 369F, and 369FF Helicopters |
| aircraft | MD Helicopters, Inc. | 369F | Airworthiness Directives; McDONNELL DOUGLAS HELICOPTER COMPANY (MDHC) (Hughes Helicopter, Inc.) Model 369D, 369E, 369F, and 369FF Helicopters |
| aircraft | MD Helicopters, Inc. | 369FF | Airworthiness Directives; McDONNELL DOUGLAS HELICOPTER COMPANY (MDHC) (Hughes Helicopter, Inc.) Model 369D, 369E, 369F, and 369FF Helicopters |
Unsafe Condition
Possible loss of power to the main rotor due to metal particles in the main transmission, excessive noise or vibration in the main transmission, or vibrations in the aircraft not reducible by main rotor blade tracking and balancing procedures.
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Required Actions
Perform dye penetrant and visual inspections on the output shaft assembly ring gear carriers per MDHC SIN DN-148.1/EN-36.1/FN-25.1. Remove from service output shafts with bulging/raised surfaces on upper disc or cracks on upper/lower disc surfaces. Install P/N 369D25132-3 ring gear carriers and reidentify main transmission as P/N 369D25100-505 to eliminate repetitive inspections.
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Compliance Time
Prior to further flight after effective date (January 15, 1988) for helicopters with issues. For others: inspections within 100 hours (if over 200 hours TIS on ring gear carrier) or at 300 hours intervals from last inspection. Compliance required as indicated unless previously done.
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Affected Aircraft
McDonnell Douglas Helicopter Company (MDHC) Models 369D, 369E, 369F, 369FF with main rotor transmission output shaft assembly ring gear carriers P/N 369D25132-BSC/-5 in main transmission assemblies P/N 369D25100-BSC/-501/-503.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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