Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Rolls-Royce, plc RB211 Trent 800 series turbofan engines, that currently requires initial and repetitive ultrasonic inspections of fan blade roots for cracks, and replacement, if necessary, with serviceable parts. This proposed action would reduce initial cyclic compliance threshold and repetitive inspection intervals. This proposal would also allow inspections to be accomplished within 100 cycles-in-service if the initial or repetitive thresholds are exceeded on the effective date of the AD. This proposal is prompted by an improved understanding of the crack propagation mechanism and the latest service operational data. The actions specified by the proposed AD are intended to prevent fan blade failure, which could result in multiple fan blade releases, uncontained engine failure, and possible damage to the airplane.