Summary
This document proposes the supersedure of an existing airworthiness directive (AD) that applies to certain serial-numbered Bell Helicopter Textron, Inc. (Bell) Model 412 helicopters and Agusta S.p.A. (Agusta) Model AB412 helicopters. That AD currently requires a temporary reduction of the never-exceed velocity (Vne) limitation until an inspection of the tail rotor yoke (yoke) assembly for fatigue damage and installation of a redesigned yoke flapping stop are accomplished. Recurring periodic and special inspections to detect occurrences of yoke overload are also required. This AD would require the same actions as the previous AD but would expand the applicability of the AD to all Bell Model 412, 412CF, 412EP, and Agusta Model AB412 helicopters. This proposal is prompted by the determination that the unsafe condition exists on all Bell Model 412 and all Agusta Model AB412 helicopters, regardless of serial number. The actions specified by the proposed AD are intended to prevent static and dynamic overload damage to the yoke that could result in loss of the tail rotor and subsequent loss of control of the helicopter.