Airworthiness Directive · Amendment 39-12479 · Enstrom Helicopter Corporation Model F-28, F-28A, F-28C, F-28F, 280, 280C, 280F and 280FX Helicopters
Enstrom Helicopter Corporation Model F-28, F-28A, F-28C, F-28F, 280, 280C, 280F and 280FX Helicopters
Superseded. A later AD replaced this one: AD 2002-08-03. Comply with the one in force.
Model F-28, F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters, certificated in any category.
This amendment supersedes an existing airworthiness directive (AD) for Enstrom Helicopter Corporation (EHC) Model F-28, F-28A, and 280 helicopters. That AD currently requires inspecting the main rotor shaft (shaft) for a crack or other evidence of damage until appropriately modifying or replacing the shaft with an airworthy shaft at specified time intervals. This amendment adds EHC Model F-28C, F- 28F, 280C, 280F, and 280FX helicopters and establishes life limits after which all unmodified shafts must be retired. This amendment requires determining the radius of the shaft fillet, certain visual and dye-penetrant inspections before further flight, and replacing certain main rotor transmissions. This amendment is prompted by the failure of a shaft on an EHC Model F-28A helicopter due to a fatigue crack. The actions specified by this AD are intended to prevent shaft failure 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.
