Airworthiness Directive · Amendment 39-10081 · McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 Helicopters
McDonnell Douglas Helicopter Systems Model 369D, E, F, FF, 500N, AH-6, and MH-6 Helicopters
Model 369D, E, F, FF, 500N, AH-6, and MH-6 helicopters, with main rotor transmission, part number (P/N) 369D25100, installed, certificated in any category.
This amendment adopts a new airworthiness directive (AD) that is applicable to McDonnell Douglas Helicopter Systems (MDHS) Model 369D, E, F, FF, 500N, AH-6, and MH-6 helicopters. This action requires replacement of certain transmission output drive gears (gears). This amendment is prompted by several reports of spalled or fractured gear teeth, most of which occurred during high-power or external-lift operations. The actions specified in this AD are intended to prevent failure of the gear, which could result in loss of main rotor control and subsequent loss of control of the helicopter.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
