Airworthiness Directive · Amendment 39-15886 · Sikorsky Aircraft Corporation Model S-92A Helicopters
Sikorsky Aircraft Corporation Model S-92A Helicopters
Superseded. A later AD replaced this one: AD 2009-13-01. Comply with the one in force.
Model S-92A helicopters with a main gearbox housing assembly, part number (P/N) 92351-15110-042, -043, or -044, that is not marked with “TS-062-01” near the P/N, certificated in any category.
This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2009-07-53, which was sent previously to all known U.S. owners and operators of Sikorsky Aircraft Corporation (Sikorsky) Model S-92A helicopters by individual letters. This amendment is prompted by the failure of 2 main gearbox filter bowl assembly studs (studs) that were found broken during a fatal accident investigation in Canada. Prior to the accident, the manufacturer was investigating a July 2008 incident that also involved broken studs. In both cases, the broken studs resulted in rapid loss of oil. The failures have been tied to fretting and galling of the original titanium studs; therefore, this AD requires removing all titanium studs and replacing them with steel studs. The actions specified by this AD are intended to prevent failure of a stud, which could result in rapid loss of oil, failure of the main gearbox, and subsequent loss of control of the helicopter.
To prevent failure of a main gearbox filter bowl assembly mounting stud (stud), which could result in rapid loss of oil, failure of the main gearbox, and subsequent loss of control of the helicopter, accomplish the following:
(a) Remove the titanium studs by following the Accomplishment Instructions in Sikorsky Alert Service Bulletin No. 92-63-014, Rev. A, dated March 20, 2009 (ASB), paragraph 3.A.
Note: Figure 1 of the ASB contains guidance for removal and installation of the studs.
(b) Visually inspect the tapped holes and the main gearbox housing lockring counterbore for damage. If you find damage in the tapped holes or in the main gearbox housing lockring counterbore, contact the Boston Aircraft Certification Office for an approved repair.
(c) Install steel studs and mark the main gearbox housing as “TS-062-01” near the P/N by following the Accomplishment Instructions in the ASB, paragraph 3.C.
(d) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Boston Aircraft Certification Office, Engine and Propeller Directorate, FAA, Attn: Kirk Gustafson, Aviation Safety Engineer, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238-7190, fax (781) 238-7170, for information about previously approved alternative methods of compliance.
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
