Summary
This notice revises an earlier proposed airworthiness directive (AD), applicable to Rolls-Royce (RR) plc RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4-B-75 series turbofan engines. That proposal would have required initial and repetitive ultrasonic inspections of low pressure compressor (LPC) fan blade roots for cracks, and relubrication of LPC fan blades before reinstallation. That proposal was prompted by the discovery of cracks on LPC fan blade roots during an engine overhaul. This action revises the proposed rule by introducing an alternative technique to ultrasonically inspect installed fan blades on-wing using a surface wave ultrasonic probe. This action also adds the application of Metco 58 blade root coating as an optional terminating action. The actions specified by this proposed AD are intended to detect cracks in LPC fan blade roots, which if not detected, could lead to uncontained multiple fan blade failure, and damage to the airplane.