Airworthiness Directives; Rolls-Royce plc Turbofan Engines
We are adopting a new airworthiness directive (AD) for certain Rolls-Royce plc (RR) RB211-Trent 970-84, RB211-Trent 970B-84, RB211- Trent 972-84, RB211-Trent 972B-84, RB211-Trent 977-84, RB211-Trent 977B-84, and RB211-Trent 980-84 turbofan engines. This AD requires inspection of the intermediate pressure compressor rear stub shaft (IPC RSS) piston ring. This AD was prompted by the failure of an oil pump drive shear neck due to a piston ring seal that was not seated properly in the IPC RSS groove. We are issuing this AD to prevent failure of the oil pump drive shear neck, which could result in loss of oil pressure in one or more engines and reduced control of the airplane.