Action
Final rule.
Summary
We are superseding airworthiness directive (AD) 2013-12-01 for all Rolls-Royce plc (RR) model RB211 Trent 768-60, 772-60, and 772B-60 turbofan engines. AD 2013-12-01 required a one-time ultrasonic inspection (UI) of low-pressure (LP) compressor blades with more than 2,500 flight cycles since new or last inspection. This AD requires initial and repetitive UIs of the affected LP compressor blades. This AD was prompted by LP compressor blade partial airfoil release events. We are issuing this AD to prevent LP compressor blade airfoil separations, damage to the engine, and damage to the airplane.