Airworthiness Directive · Amendment 39-17137 · Main rotor brake
Sikorsky Aircraft Corporation Helicopters
This AD applies to Model S-76A helicopters, with an electric rotor brake (ERB), part number (P/N) 76363-09100-012, installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-76A helicopters to require modifying the electric rotor brake (ERB) and inserting changes into the "Normal Procedures" and "Emergency Procedures" sections of the Rotorcraft Flight Manual (RFM). This AD was prompted by a fire in the main gearbox area as a result of a hot electric rotor brake (ERB). The actions are intended to prevent overheating of the ERB, ignition of the ERB hydraulic fluid, a fire in the main gearbox area, and subsequent loss of control of the helicopter.
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.
(1) Within 120 days, modify the ERB by installing:
(i) Warning relay system parts contained in modification kit, P/N 76070-55023-011, and operationally testing the ERB system in accordance with paragraphs 2.A. through 2.F., of Sikorsky Customer Service Bulletin No. 76-66-10B, Revision 2, dated November 25, 1981 (pages 1 and 9 through 13 of the service bulletin are dated November 25, 1981 and pages 2 through 8 are dated July 30, 1981);
(ii) Circuit breaker and diodes contained in ERB circuit modification kit, P/N 76070-55033-012, and operationally testing the ERB system in accordance with paragraph B. through F. of Sikorsky Customer Service Notice 76-113, dated June 1, 1983; and
(iii) Manifold, relay box, junction box, right-hand relay panel, and wiring harness parts contained in ERB modification kit, P/N 76070-55207-011, and operationally testing the ERB system in accordance with paragraphs 3.B. through 3.I. of the Accomplishment Instructions of Sikorsky Alert Service Bulletin No. 76-66-48B, Revision B, dated July 8, 2009.
(2) After accomplishing paragraph (e)(1) of this AD, insert into the Sikorsky Rotorcraft Flight Manual (RFM) the changes to the “Normal Procedures (Part 1, Section II)” and “Emergency Procedures (Part 1, Section III)” contained in Sikorsky RFM, Supplement No. 41, approved September 6, 2005.
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
