Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) for Eurocopter France (Eurocopter) Model AS350B3 helicopters with a certain modification (MOD) installed. The existing AD currently requires installing two placards and revising the Rotorcraft Flight Manual (RFM). The AD also requires certain checks and inspecting and replacing, if necessary, all four laminated half-bearings (bearings). Since we issued that AD, we have determined that the unsafe condition applies to additional model helicopters, and that a recently developed Eurocopter modification should be a required terminating action for the repetitive checks required by the AD. This proposed AD would retain the existing AD requirements, require certain modifications which would be terminating action for the airspeed limitations, and would add certain helicopter models to the bearing inspection with a different inspection interval. The proposed actions are intended to prevent vibration due to a failed bearing, failure of the tail rotor, and subsequent loss of control of the helicopter.