AD FAA-2012-1117

We are adopting a new airworthiness directive (AD) for certain Rolls-Royce plc (RR) RB211-Trent 900 series turbofan engines. This AD requires inspection of the low pressure turbine (LPT) bearing housing end cover assembly in certain engines and, if necessary, its replacement. This AD was prompted by a Trent 900 engine experiencing a high intermediate pressure vibration fault, along with other fluctuating engine parameters, while in flight. We are issuing this AD to prevent fracture of the oil transfer tube, which could result in uncontained failure of the engine and damage to the airplane.