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Federal Register / Vol. 86, No. 177 / Thursday, September 16, 2021 / Rules and Regulations For service information identified in this final rule, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, DE24 8BJ, United Kingdom; phone: +44
01332 242424; fax: +44 01332
249936; website: https www.rollsroyce.com/contact-us.aspx. You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 1200 District Avenue, Burlington, MA 01803. For information on the availability of this material at the FAA, call 781 238
7759. It is also available at https
www.regulations.gov by searching for and locating Docket No. FAA2021
0306.

ADDRESSES:

Examining the AD Docket You may examine the AD docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210306; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M
30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
Kevin Clark, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone:
781 2387088; fax: 781 2387199;
email: kevin.m.clark@faa.gov.
SUPPLEMENTARY INFORMATION:
Background The FAA issued a notice of proposed rulemaking NPRM to amend 14 CFR
part 39 to supersede AD 20201512, Amendment 3921175 85 FR 45081, July 27, 2020, AD 20201512. AD
20201512 applied to certain RRD
Trent 1000A2, Trent 1000AE2, Trent 1000C2, Trent 1000CE2, Trent 1000
D2, Trent 1000E2, Trent 1000G2, Trent 1000H2, Trent 1000J2, Trent 1000K2, and Trent 1000L2 model turbofan engines. The NPRM published in the Federal Register on April 22, 2021 86 FR 21233. The NPRM was prompted by IPC rotor blade separations resulting in engine failures.
Subsequently, the manufacturer identified the need to add new inspections and an optional terminating action, amend the asymmetric power condition for engine inspection, and to add an inspection after a cabin depressurization event. In the NPRM, the FAA proposed to continue to require initial and repetitive ultrasonic or visual
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inspection of the IPC stage 1 rotor blade root front face, IPC stage 2 rotor blade root front and rear face, and IPC shaft stage 2 dovetail post front face, removal of any cracked parts from service, and an inspection after asymmetric power and cabin depressurization events until the installation of the IPC stage 1 and stage 2 rotor blades with the IPC stage 1 and stage 2 rotor blades in kitted sets. The FAA is issuing this AD to address the unsafe condition on these products.
The European Union Aviation Safety Agency EASA, which is the Technical Agent for the Member States of the European Community, has issued EASA
AD 20200240, dated November 5, 2020
referred to after this as the MCAI, to address the unsafe condition on these products. The MCAI states:
Occurrences were reported on Rolls-Royce Trent 1000 Pack C engines, where some IPC
Rotor 1 and Rotor 2 blades were found cracked.
This condition, if not detected and corrected, could lead to in-flight blade release, possibly resulting in reduced control of the aeroplane.
To address this potential unsafe condition, Rolls-Royce initially issued Alert NMSB
TRENT 1000 72AJ814 and 72AJ819 to provide inspection instructions for IPC Rotor 1 blades, and IPC Rotor 2 blades and IPC
shaft Stage 2 dovetail posts, respectively.
Rolls-Royce also issued NMSB TRENT 1000
72J871 to provide rework instructions for the affected parts, and Alert NMSB TRENT
1000 72AJ869 to inspect those post-rework parts. Consequently, EASA issued AD 2017
0248 to require repetitive inspections of the affected IPC Rotor blades and IPC shaft Stage 2 dovetail posts and, depending on findings, removal from service of the engine for corrective action.
After that EASA AD was issued, RollsRoyce issued Alert NMSB TRENT 1000 72
AK058 to provide instructions for a one-time on-wing inspection. Consequently, EASA
issued AD 20180073, retaining the requirements of EASA AD 20170248, which was superseded, to require an additional borescope inspection of certain engines and, depending on findings, removal from service of the engine for corrective action.
After that EASA AD was issued, it was determined that repetitive borescope inspections are necessary on all engines to ensure fleet-wide continued safe operation.
Consequently, Rolls-Royce revised Alert NMSB TRENT 1000 72AJ869, Alert NMSB
TRENT 1000 72AJ814, Alert NMSB TRENT
1000 72AJ819 and NMSB TRENT 1000 72
J871, and issued NMSB TRENT 1000 72
AK060 to consolidate all inspection instructions. Consequently, EASA issued AD
20180084 later revised, retaining the requirements of EASA AD 20180073, which was superseded, and requiring repetitive onwing borescope inspections of the affected Rotor 1 parts and affected Rotor 2 parts and, depending on findings, removal from service of the engine for corrective action. That
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EASA AD also introduced specific requirements for engines installed on aeroplanes involved in ETOPS, and inspection following operation in asymmetric power conditions.
Rolls-Royce then introduced NMSB Trent 1000 72AK092 to provide inspections for the rear face of the Rotor 2 blades and NMSB
TRENT 1000 72AK060 was revised R1
accordingly. Later, Rolls-Royce developed mod 72J941, installing improved IPC Stage 1 and Stage 2 rotor blades, and issued the modification SB, providing the necessary instructions for in-service application. EASA
issued AD 20180084R2 to exclude post-mod 72J941 engines from the Applicability and introducing the modification SB as terminating action for the repetitive inspections as required by that EASA AD.
After that EASA AD was issued, RollsRoyce issued NMSB TRENT 1000 72AK313
and revised Alert NMSB TRENT 1000 72
AJ814, 72AJ819 and 72AK092 to introduce new inspections, new thresholds and new intervals, depending on engine configuration.
These inspections are for all operations, ETOPS and non-ETOPS. The latest revision of the NMSB also amended the asymmetric power conditions for engine inspection and introduced cabin depressurisation as an event to trigger engine inspections.
Consequently, EASA issued AD 20190250
to require introduction of the new inspections, replacing those previously imposed by EASA AD 20180084R2 through NMSB TRENT 1000 72AK060, and to remove the references to Engine Health Monitoring messages and ETOPS-related requirements.
Since that EASA AD was issued, it was discovered that the manufacturing distribution of the individual blade frequencies could differ from the assumed values during certification of the SB TRENT
1000 72J941, which means there may not be sufficient margin to prevent the blades from experiencing high vibration levels. Prompted by these findings, Rolls-Royce issued the modification SB to provide blade kitting instructions.

You may obtain further information by examining the MCAI in the AD
docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210306.
Discussion of Final Airworthiness Directive Comments The FAA received comments from 1
commenter. The commenter was The Boeing Company Boeing. Boeing supported the NPRM without change.
Conclusion The FAA reviewed the relevant data, considered the comment received, and determined that air safety requires adopting the AD as proposed.
Accordingly, the FAA is issuing this AD
to address the unsafe condition on these products. Except for minor editorial changes, this AD is adopted as proposed in the NPRM.

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