Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Leonardo S.p.a. Model AB139 and AW139 helicopters. This proposed AD was prompted by a large crack detected on the tail gearbox (TGB) fitting during a scheduled inspection and the determination that certain TGB fittings are required to be inspected by the use of a borescope. This proposed AD would require a one-time borescope inspection of certain part-numbered TGB fittings, and depending on the inspection results, removing the affected part from service and replacing with an airworthy part, as specified in a European Union Aviation Safety Agency (EASA) AD, which is proposed for incorporation by reference (IBR). The FAA is proposing this AD to address the unsafe condition on these products.