Airworthiness Directives; Rolls-Royce plc RB211 Trent 500 Series Turbofan Engines

The FAA is adopting a new airworthiness directive (AD) for Rolls Royce plc (RR) RB211 Trent 500 series turbofan engines. This AD requires initial and repetitive borescope inspections of the high pressure-and-intermediate pressure (HP-IP) turbine oil vent tubes and bearing chambers for coking and carbon buildup and replacing the vent tubes if necessary. This AD results from a report of an RB211 Trent 700 series engine that experienced a disk shaft separation, overspeed of the IP turbine rotor, and multiple blade release of IP turbine blades. Since the design arrangement in the Trent 500 series engines is similar to that of the Trent 700 series engines, the same failure could occur in the Trent 500 series engines. We are issuing this AD to prevent internal oil fires caused by coking and carbon buildup, that could result in uncontained engine failure and damage to the airplane.