AD 97-15-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | MD Helicopters, Inc. | 369D | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 Helicopters |
| aircraft | MD Helicopters, Inc. | 369E | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 Helicopters |
| aircraft | MD Helicopters, Inc. | 369F | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 Helicopters |
| aircraft | MD Helicopters, Inc. | 369FF | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 Helicopters |
| aircraft | MD Helicopters, Inc. | 500N | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 Helicopters |
Unsafe Condition
Failure of the transmission output drive gear (part number 369D25127-11) with serial numbers 005570-0646 through 005570-0765, or 005570-0876 through 005570-0998, due to spalled or fractured gear teeth resulting from warping during carburizing heat treatment and grinding through the hardened case, which could lead to jamming or binding of the drive system, loss of main rotor control, 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
Within 10 hours time-in-service after the effective date, inspect records or physically inspect to determine if an affected gear serial number is installed. If an affected gear is found, remove and replace it with an airworthy gear within specified timeframes based on external load operation logs: 25 hours TIS for external load operations or 400 hours TIS for non-external load operations, whichever comes first. Helicopters without cargo hook assemblies must replace within the same compliance times as non-external load operations.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 10 hours time-in-service after the effective date of this AD for inspection. Replacement must occur within 25 hours TIS for external load operations or 400 hours TIS for non-external load operations, or within 400 hours TIS for helicopters without cargo hook assemblies.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 helicopters equipped with main rotor transmission part number 369D25100 and transmission output drive gear part number 369D25127-11 with serial numbers 005570-0646 through 005570-0765, or 005570-0876 through 005570-0998.
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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