Airworthiness Directives; Eurocopter France Model SA-365N, SA- 365N1, and SA-366G1 Helicopters

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 97-15-15, which was sent previously to all known U.S. owners and operators of Eurocopter France Model SA-365N, SA-365N1, and SA-366G1 helicopters by individual letters. This AD requires an inspection of the main gearbox magnetic plug (magnetic plug) and the main gearbox oil filter (oil filter) for ferrous chips; vibration measurements, if necessary; and replacement of the main gearbox if a specified quantity of ferrous chips are discovered, or if abnormal vibrations are identified at a certain frequency. This amendment is prompted by two recent reports of cracks found in planetary gear shafts (gear shafts) in main gearboxes that have not been modified in accordance with MOD 077244. The actions specified by this AD are intended to detect cracks in the gear shaft which could lead to failure of the gear shaft, failure of the transmission, and subsequent loss of control of the helicopter.