Airworthiness Directive · Amendment 39-19385 · Turbine section
Rolls-Royce plc Turbofan Engines
This AD applies to all 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 that have not incorporated the modifications introduced by RR Alert Service Bulletin RB.211-72-AJ592, dated September 4, 2017.
We are superseding Airworthiness Directive (AD) 2013-02-04 for all 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. AD 2013-02-04 required 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. This AD requires additional criteria for the inspection of the stage 2, 3, and 4 LPT disk seal fins and interstage seals and removes the requirement to inspect the stage 5 LPT disk seal fins and interstage seal. This AD was prompted by a Trent 900 engine experiencing increased low-pressure rotor vibration while in flight resulting in an in-flight shutdown (IFSD) and air turnback. We are issuing this AD to address the unsafe condition on these products.
(1) After the effective date of this AD, after every flight, review the Engine Health Monitoring low-pressure rotor (N1) vibration data within 10 engine flight cycles (FCs).
(i) If you find that the maximum and average vibrations exceed 0.7 inches/sec (ips) and 0.5 ips, respectively, then within 10 engine FCs:
(A) Confirm that the vibration data was not the result of indicator error.
(B) If you cannot show that the vibration increase was caused by indicator error, inspect the LPT stage 2, 3, and 4 disk seal fins and interstage seals in accordance with the Accomplishment Instructions, paragraph 3.B., of RR Alert Non-Modification Service Bulletin (NMSB) RB.211-72-AH054, Revision 3, dated February 1, 2018.
(ii) Reserved.
(2) After the effective date of this AD, each time a pass-off test is performed on an engine after induction into a Repair and Overhaul Shop, inspect the LPT stage 2, 3, and 4 disk seal fins and interstage seals in accordance with the Accomplishment Instructions, paragraph 3.C., of RR Alert NMSB RB.211-72-AH054, Revision 3, dated February 1, 2018.
(4) If, during the inspections required by paragraph (g) of this AD, you find any cracks in the disk seal fins or any interstage seals are missing seal material, replace the parts with parts eligible for installation before further flight.
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.
