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Notice of proposed rulemaking (NPRM).

We propose to adopt a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (type certificate previously held by Schweizer Aircraft) (Sikorsky) Model 269D and Model 269D Configuration A helicopters. This proposed AD would require reducing the life limit of the ring gear carrier assembly. This proposed AD is prompted by cracks in the ring gear carrier assembly. The proposed actions are intended to reduce the life of the ring gear carrier assembly to prevent failure of the main rotor transmission, loss of engine power to the main rotor, and subsequent loss of control of the helicopter.

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