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Action

Final rule; request for comments.

Summary

We are superseding an existing airworthiness directive (AD) for all Rolls-Royce plc (RR) models RB211-Trent 970-84, 970B-84, 972- 84, 972B-84, 977-84, 977B-84, and 980-84 turbofan engines. That AD currently requires inspecting the intermediate-pressure (IP) shaft rigid coupling splines for wear resulting in rearward movement of the IP turbine. This AD requires the same inspections, and new inspections based on possible changes in wear rate. This AD was prompted by RR identifying wear beyond engine manual limits on the abutment faces of the splines. RR also determined that an additional IP shaft rigid coupling configuration requires inspection. We are issuing this AD to detect wear on the abutment faces of the splines, which could result in loss of disc integrity, an uncontained failure of the engine, and damage to the airplane.

Document

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