Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A Helicopters

Résumé

This document proposes adopting a new airworthiness directive (AD) for the Sikorsky Aircraft Corporation (Sikorsky) Model S-76A helicopters. This proposal would require modifying the electric rotor brake (ERB). Thereafter, the AD would also require inserting changes to the "Normal Procedures" and "Emergency Procedures" sections of the Rotorcraft Flight Manual (RFM), which revises the information of the basic RFM when the ERB is installed. This proposal is prompted by a reported incident of a fire occurring in an ERB installed on a Model S- 76A helicopter. The actions specified by this proposed AD are intended to prevent overheating of the ERB assembly, ignition of the ERB hydraulic fluid, a fire in the main gearbox area, and subsequent loss of control of the helicopter.