FAA revised airworthiness directive for Sikorsky

FAA is revising an earlier proposed airworthiness directive (AD) for certain Sikorsky Aircraft Corporation (Sikorsky) Model S–61A, D, E, L, N, NM, R, and V; Croman Corporation Model SH–3H, Carson Helicopters, Inc., Model S–61L; Robinson Air Crane models and more. This SNPRM is prompted by comments received in response to a previous SNPRM and a reevaluation of the relevant data. This SNPRM retains the proposed actions in the previous SNPRM, provides an increased estimated cost of the main rotor shaft (MRS) replacement, and clarifies some of the language in the Required Actions section of the AD. The proposed actions are intended to prevent MRS structural failure, loss of power to the main rotor, and subsequent loss of control of the helicopter.   FAA is proposing this SNPRM after evaluation all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other helicopters of these same type designs. Certain changes described above expand the scope of the previous SNPRM (78 FR 24363, April 25, 2013) by increasing the economic burden. FAA estimates that this proposed AD would affect 60 helicopters of U.S. registry.   Source and image: GPO