Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for Rolls-Royce plc (RR) RB211-22B series, RB211-524B, - 524C2, -524D4, -524G2, -524G3, and -524H series, and RB211-535C and - 535E series turbofan engines with high pressure compressor (HPC) stage 3 disc assemblies, part numbers (P/Ns) LK46210, LK58278, LK67634, LK76036, UL11706, UL15358, UL22577, UL22578, and UL24738 installed. That AD requires removing from service certain disc assemblies before they reach their full life if not modified with anticorrosion protection. This proposed AD would require the same actions as AD 2004- 01-20, but would shorten the compliance time for disks that entered service before 1990. This proposed AD results from the manufacturer's reassessment of the corrosion risk on HPC stage 3 disc assemblies not modified with sufficient application of anticorrosion protection. We are issuing this AD to prevent corrosion-induced uncontained disc failure, resulting in damage to the airplane.