Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211-Trent 553-61, 553A2-61, 556-61, 556A2-61, 556B-61, 556B2-61, 560-61, 560A2-61, 768-60, 772-60, 772B-60, 875-17, 877-17, 884-17, 884B-17, 892-17, 892B-17, and 895-17 turbofan engines. The existing AD currently requires inspection of the intermediate-pressure (IP) compressor rotor shaft rear balance land for cracks. Since we issued that AD, a crack was detected in a Trent 500 IP compressor rotor shaft rear balance land during a shop visit, and further engineering evaluation done by RR concluded that the cracking may also exist in Trent 900 engines. This proposed AD would require inspections of the IP compressor rotor shaft as required by the existing AD while adding on-wing inspections for the Trent 500 engines, and on-wing and in-shop inspections for the Trent 900 engines. We are proposing this AD to detect cracking on the IP compressor rotor shaft rear balance land, which could lead to uncontained engine failure and damage to the airplane.