Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Model EC155B1 helicopters. This proposed AD was prompted by reports of failure of the main gearbox (MGB) oil cooling fan hub (fan hub). This proposed AD would require for helicopters with an affected part (fan hub) installed, using an endoscope, repetitively inspecting the fan hub, including the area around the fan hub attachment screws, for a crack. Depending on the inspection results, this proposed AD would require performing additional inspections and replacing an affected fan hub. This proposed AD would also allow an affected fan hub to be installed on a helicopter if certain actions are accomplished, as specified in a European Union Aviation Safety Agency (EASA) AD, which is proposed for incorporation by reference. The FAA is proposing this AD to address the unsafe condition on these products.