Action
Final rule; request for comments.
Summary
We are adopting a new airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211-Trent 970-84, 970B-84, 972-84, 972B-84, 977- 84, 977B-84, and 980-84 turbofan engines. This AD requires replacement of the fuel oil heat exchanger (FOHE). This AD was prompted by a report of an in-flight increase of N2 intermediate pressure rotor vibrations resulting in an engine surge and pilot shut down of the engine. We are issuing this AD to prevent rotor bearing oil starvation, uncontained engine failure, and damage to the airplane.