Airworthiness Directive · Amendment 39-16710 · -13-p
Sikorsky Aircraft Corporation (Sikorsky) Model S-92A Helicopters
Model S-92A helicopters with main gearbox (MGB) upper housing assembly, part number (P/N) 92351-15110-042, -043, -044, -045, or -046, installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for the Sikorsky Model S-92A helicopters. This AD requires a nondestructive inspection (NDI), eddy current or fluorescent penetrant inspection (FPI), of each main gearbox (MGB) upper housing assembly rib on the left, right, and forward MGB mounting foot at specified intervals based on the MGB upper housing assembly hours time-in-service (TIS). If there is a crack, this AD requires replacing the MGB upper housing assembly with an airworthy MGB upper housing assembly. This AD is prompted by a report of a crack found on the MGB upper housing assembly left mounting foot forward rib that cannot be detected visually. We are issuing this AD to prevent loss of the MGB and subsequent loss of control of the helicopter.
For each MGB upper housing assembly with 700 or more hours time-in-service (TIS), within 30 hours TIS, unless already done, or for each MGB upper housing assembly with more than 500 hours TIS but less than 700 hours TIS, within 50 hours TIS, unless already done, and for all helicopters thereafter at intervals not to exceed 50 hours TIS:
(1) Clean and Eddy Current inspect the forward, left, and right MGB mounting foot ribs for a crack by following the Accomplishment Instructions, paragraphs 3.C. through 3.D.(2)(d), of Sikorsky Alert Service Bulletin No. 92-63-025A, Revision A, dated May 12, 2011 (ASB); or
(2) Clean and fluorescent penetrant inspect (FPI) the MGB mounting foot ribs for a crack by following the Accomplishment Instructions, paragraphs 3.E.(1) through 3.E.(5), of the ASB.
(3) An inspector qualified to ASNT Level II or equivalent is required to perform the nondestructive inspection (NDI), by Eddy Current or FPI, of the left, right, and forward MGB mounting foot ribs for a crack.
(f) If there is a crack, before further flight, replace the MGB upper housing assembly with an airworthy MGB upper housing assembly.
Note: Sikorsky has developed a Phase III MGB upper housing assembly, P/N 92351-15310-041, is not subject to the “Applicability” of this AD.
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.
Aircraft
