Summary
We propose to supersede airworthiness directive (AD) 2008-22- 24 which applies to certain Rolls-Royce plc (RR) RB211-535E4-37, RB211- 535E4-B-37, and RB211-535E4-B-75 model turbofan engines. AD 2008-22-24 requires initial and repetitive ultrasonic inspections of installed low-pressure compressor (LPC) fan blade roots on-wing and during overhaul, and relubrication according to accumulated life cycles. Since we issued AD 2008-22-24, RR determined the need to expand the inspections to engines operating under additional flight profiles and to extend the inspection intervals for certain affected engines. This proposed AD would require initial and repetitive inspections to detect cracks on the installed LPC fan blade roots on-wing or at engine overhaul. We are proposing this AD to address the unsafe condition on these products.