Airworthiness Directives; Rolls-Royce plc RB211 Trent 700 Series Turbofan Engines

The FAA is superseding an existing airworthiness directive (AD) for Rolls-Royce plc (RR) RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 turbofan engines with low pressure compressor (LPC) fan blade part numbers FK22580, FK23411, FK25441, and FK25968 installed. That AD currently requires initial ultrasonic inspections of the fan blade root with blades removed, repetitive ultrasonic inspections of the fan blade root with blades removed or installed, and ultrasonic inspection of the fan blade root to be done with the fan blades removed at least every third inspection. This AD requires the same inspections but at lower thresholds and intervals, and eliminates the requirement for ultrasonic inspection with the fan blades removed at least every third inspection. This AD results from analysis of flight data returned to RR, that shows a need for consistent inspection thresholds for all engine models. We are issuing this AD to prevent possible multiple LPC fan blade failures, which could result in an uncontained engine failure and damage to the airplane.