Airworthiness Directives; Carson Helicopters, Inc.; Croman Corporation; Sikorsky Aircraft Corporation; and Siller Helicopters

The FAA is adopting a new airworthiness directive (AD) for all Carson Helicopters, Inc., Model S-61L and SH-3H helicopters; Croman Corporation Model SH-3H helicopters; Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, and S-61V helicopters; and Siller Helicopters Model CH-3E and SH-3A helicopters. This AD was prompted by an accident. This AD requires tracking hours time-in-service (TIS) and external lift cycles (lift cycles) for certain main gearbox left and right input freewheel unit (IFWU) assemblies. This AD also requires determining the type of IFWU assembly installed and depending on the results, calculating the moving average, repetitive inspections, recording certain information, replacing parts, and marking parts. The FAA is issuing this AD to address the unsafe condition on these products.