Airworthiness Directive · Amendment 39-9960 · Bell Helicopter Textron, Inc. Helicopters
Bell Helicopter Textron, Inc. Helicopters
This AD applies to Bell Helicopter Textron, Inc. 214ST.
The models as the FAA's AD index lists them. The serial ranges, installed parts and exceptions are in the AD itself: read it at the FAA.
This amendment supersedes an existing airworthiness directive (AD), applicable to Bell Helicopter Textron, Inc. (BHTI) Model 214ST helicopters, that currently establishes a mandatory retirement life of 50,000 high-power events for the main rotor mast (mast). This amendment requires changing the retirement life for the mast from high-power events to a maximum accumulated Retirement Index Number (RIN) of 140,000 and applying this RIN to an additional part-numbered mast. This amendment is prompted by fatigue analyses and tests that show certain masts fail sooner than originally anticipated because of an unanticipated high number of takeoffs and external load lifts in addition to the deterioration in strength that occurs under other operating conditions. The actions specified by this AD are intended to prevent fatigue failure of the mast, which could result in failure of the main rotor system 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.
