AD 99-04-12
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | MD Helicopters, Inc. | 369D | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters |
| aircraft | MD Helicopters, Inc. | 369E | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters |
| aircraft | MD Helicopters, Inc. | 369FF | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters |
| aircraft | MD Helicopters, Inc. | 369H | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters |
| aircraft | MD Helicopters, Inc. | 500N | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters |
| aircraft | MD Helicopters, Inc. | 600N | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters |
Unsafe Condition
Failure of the spline teeth in the input shaft coupling assembly, leading to loss of drive to the main rotor system and subsequent loss of control of the helicopter.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Visually inspect the input shaft coupling assemblies (P/N 369F5133-1) for pitting under the solid film lubricant in the spline area. Replace the coupling assembly if pitting is found.
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Compliance Time
within 100 hours time-in-service after the effective date of this AD
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Affected Aircraft
McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N helicopters with input shaft coupling assemblies, P/N 369F5133-1, serial numbers 030829-0126 through 030829-0207, installed on main transmission P/N 369F5100-503 and overrunning clutch P/N 369F5450.
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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