Airworthiness Directives; Rolls-Royce plc Models RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 Turbofan Engines

The FAA is adopting a new airworthiness directive (AD) for Rolls-Royce plc (RR) models RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 turbofan engines. This AD requires initial and repetitive borescope inspections of the high pressure-intermediate pressure (HP- IP) turbine bearing internal oil vent tube, scavenge tube, and tube heat shields for wear and cracking, and removing tubes from service if found with any cracks beyond serviceable limits. This AD also requires installation of a new or modified HP-IP turbine bearings support as terminating action for the repetitive borescope inspections. This AD results from two reports of RR RB211 Trent 700 series engines found with the HP-IP internal oil vent tube and scavenge tube fretted by damaged heat shields on the tubes. We are issuing this AD to prevent oil ejecting from the HP-IP turbine bearings chamber and igniting. Burning oil can cause the intermediate pressure (IP) shaft to fracture, the IP turbine to overspeed, and possible uncontained failure of the engine.