Summary
We propose to supersede airworthiness directive (AD) 2016-04- 12 that applies to certain Turbomeca S.A. Arriel 2B, 2B1, 2C, 2C1, 2C2, 2D, 2E, 2S1, and 2S2 turboshaft engines. AD 2016-04-12 requires spectrometric oil analysis (SOA) inspection of the engine accessory gearbox (AGB), and, depending on the results, removal of the engine AGB. Since we issued AD 2016-04-12, we determined that wear inspections of the engine AGB cover are also required. This proposed AD would require initial and repetitive inspections of the AGB, and wear inspections of the engine AGB cover. We are proposing this AD to prevent failure of the engine AGB, uncommanded in-flight shutdown (IFSD), damage to the engine, and damage to the helicopter.