Airworthiness Directives; Bell Helicopter Textron, Inc. Model 205A, 205A-1, 205B, 212, and 412 Series Helicopters

Riepilogo

This amendment adopts a new airworthiness directive (AD), applicable to Bell Helicopter Textron, Inc. Model 205A, 205A-1, 205B, 212, and 412 series helicopters, that requires removal and replacement of a certain design main transmission lower planetary spider (spider), and establishes a 2,500 hours time-in-service retirement life for the spider. This amendment is prompted by five failures of the spider that occurred during the manufacturer's fatigue tests. The actions specified by this AD are intended to prevent fatigue failure of the spider, failure of the main transmission, and subsequent loss of control of the helicopter.