Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for Rolls-Royce plc (RR) models RB211 Trent 875-17, Trent 877-17, Trent 884-17, Trent 884B-17, Trent 892-17, Trent 892B-17, and Trent 895-17 turbofan engines with low pressure (LP) compressor fan blades, part number (P/N) FW18548 installed. That AD currently requires LP compressor fan blade replacement with new or previously reworked blades, or rework of the existing LP compressor fan blades. This proposed AD would require the same actions but at reduced compliance times for certain airplane and engine rating combinations and certain maximum gross weight limits. This proposed AD results from a number of new production LP compressor blades found with surfaces formed outside of design intent. We are proposing this AD to prevent possible multiple uncontained LP compressor fan blade failure, due to cracking in the blade root caused by increased stresses in the shear key slots.