Airworthiness Directive · Amendment 39-17250 · Engine controls
Sikorsky Aircraft Corporation Helicopters
This AD applies to Sikorsky Aircraft Corporation (Sikorsky) Model S-76C helicopters, serial numbers 760506 and 760607 through 760812, certificated in any category.
We are adopting a new airworthiness directive (AD) for certain Sikorsky Aircraft Corporation (Sikorsky) Model S-76C helicopters. This AD requires installing an improved throttle stop and a wider trigger on the engine control levers (ECL). This AD was prompted by a bird-strike to the windshield that resulted in unintended movement of the engine control levers from the forward position and towards the flight-idle position, which reduced power on both engines. These actions are intended to prevent unintended movement of the ECLs, resulting in main rotor speed decay and subsequent loss of control of the aircraft.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
Within 6 months, replace the throttle stop and trigger assembly on each engine control lever and perform a throttle position check as specified in the Accomplishment Instructions, Sections 3.A and 3.B, of Sikorsky Alert Service Bulletin No. 76-76-6A Revision A, dated May 18, 2011.
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.
