AD NUMBER: 2018-18-06

PRODUCT: 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.

ACTION: Final Rule; request for comments.

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2013-02-04 for the engines listed above.

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.

DATES: This AD is effective September 20, 2018. Comments must be received by October 22, 2018.

COST: The FAA estimates that this AD affects 0 engines installed on airplanes of U.S. registry. The cost of compliance is estimated as follows:
Inspection of LPT disk seal fins and interstage seals 8 work-hours × $85 per hour = $680 per engine.

FMI: AD