Summary
This action withdraws a notice of proposed rulemaking (NPRM). That NPRM proposed a new airworthiness directive (AD) that applies to Rolls-Royce plc (RR) RB211 Trent 800 series turbofan engines. That proposed action would have required initial and repetitive borescope inspections of the high pressure-and-intermediate pressure (HP-IP) turbine internal and external oil vent tubes for coking and carbon buildup, and cleaning or replacing the vent tubes if necessary. Since we issued that NPRM, RR notified us that the RB211 Trent 800 series turbofan engines are significantly less susceptible to vent tube carbon build-up than the RB211 Trent 700 series turbofan engines. Repeat on-wing inspections therefore, are not required to maintain fleet safety. Accordingly, we withdraw the proposed rule.