Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all RR model RB211-524G2-T-19, -524G3-T-19, -524H- T-36, and -524H2-T-19; and RB211-Trent 553-61, 553A2-61, 556-61, 556A2- 61, 556B-61, 556B2-61, 560-61, 560A2-61; RB211-Trent 768-60, 772-60, 772B-60; and RB211-Trent 875-17, 877-17, 884-17, 884B-17, 892-17, 892B- 17, and 895-17 turbofan engines that have a high-pressure (HP) compressor stage 1 to 4 rotor disc with a part number (P/N) listed in Table 1 of this proposed AD. The existing AD currently requires repetitive inspections of the axial dovetail slots, and follow-on corrective action depending on findings. Since we issued that AD, we determined that the definition of shop visit is too restrictive in the existing AD. This proposed AD would continue to require those repetitive inspections and follow-on corrective actions, and it would change the definition of a shop visit to be less restrictive. We are proposing this AD to detect cracks in the HP compressor stage 1 and 2 disc posts, which could result in failure of the disc post and HP compressor blades, release of uncontained engine debris, and damage to the airplane.