Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

We propose to adopt a new airworthiness directive (AD) for certain Turbomeca S.A. Arriel 2B, 2B1, 2C, 2C1, 2C2, 2D, 2E, 2S1, and 2S2 turboshaft engines. This proposed AD was prompted by a report of an uncommanded in-flight shutdown of an Arriel 2 engine caused by rupture of the 41-tooth gear, which forms part of the bevel gear in the engine accessory gearbox (AGB). This proposed AD would require inspection, and, depending on the results, removal of the engine AGB. We are proposing this AD to prevent failure of the engine AGB, which could lead to in-flight shutdown, damage to the engine, and damage to the aircraft.