Summary
We propose to adopt a new airworthiness directive (AD) for the Eurocopter France Model AS 350 B, BA, B1, B2, B3, and D, and Model AS355 E, F, F1, F2, and N helicopters, with certain main rotor servo- controls and tail rotor servo-controls. This proposed AD would require replacing all servo-controls that are identified in the Applicability section of this proposed AD. This proposed AD is prompted by an internal review conducted by the manufacturer which revealed that some main and tail rotor servo-controls do not conform to the approved design. The actions specified by this proposed AD are intended to prevent the distributor slide valve jamming in its sleeve, leading to reduced controllability of the rotors and subsequent loss of control of the helicopter.