Airworthiness Directives; Rolls-Royce plc RB211 Trent 700 Series Turbofan Engines

The FAA is adopting a new airworthiness directive (AD) for Rolls-Royce plc (RR) RB211 Trent 700 series turbofan engines. This AD requires 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. This AD results from a report of a RB211 Trent 700 series engine experiencing a disk shaft separation, overspeed of the IP turbine rotor, and multiple blade release of IP turbine blades. Preliminary findings suggest these events resulted from an internal oil fire in the HP-IP turbine oil vent tubes due to coking and carbon buildup. This fire led to a second fire in the internal air cavity below the IP turbine disk drive shaft. We are issuing this AD to prevent internal oil fires due to coking and carbon buildup, that could cause uncontained engine failure and damage to the airplane.