Airworthiness Directive · Amendment 39-17325 · Rolls-Royce plc Turbofan Engines
Rolls-Royce plc Turbofan Engines
Superseded. A later AD replaced this one: AD 2018-18-06. Comply with the one in force.
This AD applies to 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 engines, all serial numbers.
We are adopting a new airworthiness directive (AD) for all Rolls-Royce plc 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 on-wing inspections of low-pressure turbine (LPT) disk seal fins and interstage seals when post-flight review indicates Engine Health Monitoring (EHM) vibratory maintenance-alert limits were exceeded in flight. The AD also requires in-shop inspections of the LPT disk seal fins and interstage seals to detect cracks or damage and, depending on the findings, accomplishment of corrective action. This AD is prompted by a Trent 900 engine experiencing LPT stage 2 disk interstage seal material loss and increased low-pressure rotor vibration while in flight. We are issuing this AD to prevent cracks in the LPT disk, which could result in uncontained engine failure and damage to the airplane.
Unless already done, do the following.
(1) After every flight after the effective date of this AD, review the Engine Health Monitoring (EHM) low-pressure rotor (N1) vibration data. If you find that the maximum and average vibrations exceed 0.7 inches/sec (ips) and 0.5 ips, respectively, then within 10 engine flight cycles, confirm that the vibration data was not the result of indicator error.
(2) If you cannot show that the vibration increase was caused by indicator error, inspect the LPT disk seal fins and interstage seals. Use RR Repeater Technical Variance 125060, Issue 1, dated July 27, 2012, to do the inspections.
(3) After the effective date of this AD, at each engine shop visit inspect the LPT disk seal fins and interstage seals. Use RR Alert Non-Modification Service Bulletin RB.211-72-AH054, Revision 1, dated November 5, 2012, or Initial Issue, dated September 14, 2012, to do the inspections.
(4) If, during the inspection required by paragraphs (e)(2) or (e)(3) of this AD, you find any cracks in the disk seal fins or that the interstage seals are missing seal material, replace the parts with hardware eligible for installation before returning the engine to service.
For the purposes of this AD, a shop visit is defined as whenever engine maintenance performed prior to reinstallation requires one of the following:
(1) Separation of a pair of major mating engine module flanges. However, separation of flanges solely for the purpose of shipment without subsequent internal maintenance is not a shop visit. Separation of the external gearbox engine mating flanges or removal of the external gearbox is also not classified as a shop visit.
(2) Removal of a disk, hub, or spool.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Engines
