Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG (Type Certificate Previously Held by Rolls-Royce plc) Turbofan Engines, 61083-61085 [2021-24056]

Download as PDF Federal Register / Vol. 86, No. 212 / Friday, November 5, 2021 / Proposed Rules DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2021–0662; Project Identifier MCAI–2021–00031–E] RIN 2120–AA64 Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG (Type Certificate Previously Held by RollsRoyce plc) Turbofan Engines Federal Aviation Administration (FAA), DOT. ACTION: Supplemental notice of proposed rulemaking (SNPRM). AGENCY: The FAA is revising a notice of proposed rulemaking (NPRM) that applied to certain Rolls-Royce Deutschland Ltd & Co KG (RRD) Trent 1000 model turbofan engines. This action revises the NPRM by reopening the comment period because the NPRM was placed in incorrect Docket No. FAA–2021–0637 instead of Docket No. FAA–2021–0662. The FAA is proposing this airworthiness directive (AD) to address the unsafe condition on these products. Since commenters experienced difficulties in commenting on the NPRM, the FAA is requesting comments on this SNPRM. DATES: The FAA must receive comments on this SNPRM by December 20, 2021. ADDRESSES: You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods: • Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments. • Fax: (202) 493–2251. • Mail: U.S. Department of Transportation, Docket Operations, M– 30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue SE, Washington, DC 20590. • Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. For service information identified in this SNPRM, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, DE24 8BJ, United Kingdom; phone: +44 (0)1332 242424; fax: +44 (0)1332 249936; website: https:// www.rolls-royce.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. jspears on DSK121TN23PROD with PROPOSALS1 SUMMARY: VerDate Sep<11>2014 17:04 Nov 04, 2021 Jkt 256001 Examining the AD Docket You may examine the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA–2021–0662; 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 SNPRM, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above. FOR FURTHER INFORMATION CONTACT: Kevin Clark, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: (781) 238–7088; fax: (781) 238–7199; email: kevin.m.clark@faa.gov. SUPPLEMENTARY INFORMATION: Comments Invited The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under ADDRESSES. Include ‘‘Docket No. FAA–2021–0662; Project Identifier MCAI–2021–00031–E’’ at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend this proposal because of those comments. Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to https:// www.regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this proposed AD. Confidential Business Information CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this SNPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this SNPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as ‘‘PROPIN.’’ The FAA will treat such marked submissions as PO 00000 Frm 00003 Fmt 4702 Sfmt 4702 61083 confidential under the FOIA, and they will not be placed in the public docket of this SNPRM. Submissions containing CBI should be sent to Kevin Clark, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking. Background The FAA issued an NPRM to amend 14 CFR part 39 by adding an AD that would apply to RRD Trent 1000–AE3, Trent 1000–CE3, Trent 1000–D3, Trent 1000–G3, Trent 1000–H3, Trent 1000– J3, Trent 1000–K3, Trent 1000–L3, Trent 1000–M3, Trent 1000–N3, Trent 1000– P3, Trent 1000–Q3, and Trent 1000–R3 model turbofan engines. The NPRM published in the Federal Register on August 13, 2021 (86 FR 44655). The NPRM was prompted by reports of high levels of wear on the seal fins on a small number of certain high-pressure turbine triple seals. In the NPRM, the FAA proposed to require manual deactivation of the modulated air system (MAS) control valves. The European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA AD 2021–0009, dated January 8, 2021 (referred to after this as ‘‘the MCAI’’), to address the unsafe condition on these products. The MCAI states: The Modulated Air System (MAS) optimises cooling air, extracted from the compressor, where full flow is not required at cruise conditions. It is only active during cruise. Recently, occurrences have been reported of finding high levels of wear on the seal fins on a small number of high pressure turbine triple seals, Part Number FW34485. The effect on the secondary air system was conservatively assessed due to the resultant increased turbine cooling air leakage, which changes the cooling flow around the intermediate pressure (IP) turbine disc. This condition, if not corrected, could lead to temperature increase at the IP turbine disc rim when the MAS is active, possibly resulting in IP turbine disc failure and high energy debris release, with consequent damage to, and reduced control of, the aeroplane. To address this potential unsafe condition, Rolls-Royce has issued the NMSB, providing instructions to manually ‘lock-out’ (deactivate) the MAS control valves. For the reason described above, this [EASA] AD requires to deactivate the MAS control valves. This [EASA] AD also specifies that the Master Minimum Equipment List (MMEL) item for ‘MAS inoperative’, which has a limit of 120 days, does not apply when the system is manually deactivated. You may obtain further information by examining the MCAI in the AD E:\FR\FM\05NOP1.SGM 05NOP1 61084 Federal Register / Vol. 86, No. 212 / Friday, November 5, 2021 / Proposed Rules docket at https://www.regulations.gov by searching for and locating Docket No. FAA–2021–0662. Actions Since the NPRM Was Issued Since the FAA issued the NPRM, the FAA determined the NPRM was inadvertently placed in incorrect Docket No. FAA–2021–0637 instead of Docket No. FAA–2021–0662. The FAA received information that the public had difficulty commenting on the NPRM. Comments The FAA received comments on the NPRM from two commenters. The following presents the comments received on the NPRM and the FAA’s response to each comment. The FAA updated paragraph (e) of this proposed AD by stating, ‘‘This AD was prompted by reports of high levels of wear on the seal fins on a small number of certain high-pressure turbine triple seals. The FAA is issuing this AD to ensure cooling airflow restoration to the intermediate-pressure turbine (IPT) disk rim during cruise by deactivating the modulated air system (MAS). The unsafe condition, if not addressed, could result in a temperature increase at the IPT disk rim, when the MAS is active during cruise, resulting in failure of the IPT disk, loss of engine thrust control, and loss of the airplane.’’ Request To Correct Part Number Reference Request To Revise the Unsafe Condition The Boeing Company (Boeing) requested the FAA revise paragraph (e), Unsafe Condition, of the NPRM to accurately reflect the effect of the AD on the unsafe condition. Boeing suggested revising paragraph (e) to state ‘‘This AD was prompted by reports of high levels of wear on the seal fins on a small number of certain high-pressure turbine (HPT) triple seals. This condition, if not addressed, could lead to temperature increase at the Intermediate Pressure (IP) turbine disk rim when the Modulated Air System (MAS) is active during cruise, possibly resulting in failure of the IP turbine disk, loss of engine thrust control, and loss of the airplane. The FAA is issuing this AD to restore cooling airflow to the IP turbine disk rim during cruise by deactivating MAS.’’ Boeing reasoned that the AD action to deactivate the MAS does not prevent wear on the HPT triple seal fins. Deactivating the MAS restores cooling airflow to the intermediate-pressure turbine (IPT) disk rim during cruise. Rolls-Royce notified the FAA that the preamble of the NPRM incorrectly identifies the HPT triple seal part number (P/N) as FW3448, whereas the correct identification is FW34485. The FAA agrees and has revised the Background section of this proposed AD by correcting the reference to the HPT triple seal P/N from FW3448 to FW34485. FAA’s Determination This product has been approved by EASA and is approved for operation in the United States. Pursuant to the FAA’s bilateral agreement with the European Community, EASA has notified the FAA of the unsafe condition described in the MCAI and service information. The FAA is proposing this AD because the agency evaluated all the relevant information provided by EASA and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. The public had difficulty commenting on the NPRM. As a result, the FAA has determined that it is necessary to reopen the comment period to provide opportunity for the public to comment on this SNPRM. Related Service Information Under 1 CFR Part 51 The FAA reviewed Rolls-Royce Alert Non-Modification Service Bulletin Trent 1000 75–AK642, Initial Issue, dated November 30, 2020. The service information specifies procedures for deactivating the MAS control valves. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in ADDRESSES. Proposed Requirements in This SNPRM This proposed AD would require manual deactivation of the MAS control valves. Manual deactivation of the MAS control valves changes the engine to an approved configuration that will produce engine indicating and crew alerting system (EICAS) status messages that do not indicate inoperative (failed) equipment. Consequently, when these messages are displayed, the operator’s existing FAA-approved minimum equipment list (MEL) instructions and limitations, including the 120-day operation limitation, do not apply. Interim Action The FAA considers this proposed AD would be an interim action. If final action is later identified, the FAA might consider additional rulemaking. Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 4 engines installed on airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD: ESTIMATED COSTS Action Labor cost Deactivate the MAS control valves ................. 2 work-hours × $85 per hour = $170 ............. jspears on DSK121TN23PROD with PROPOSALS1 Authority for This Rulemaking Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency’s authority. The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section VerDate Sep<11>2014 17:04 Nov 04, 2021 Jkt 256001 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. PO 00000 Frm 00004 Fmt 4702 Sfmt 4702 Cost per product Parts cost $0 $170 Cost on U.S. operators $680 Regulatory Findings The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. E:\FR\FM\05NOP1.SGM 05NOP1 Federal Register / Vol. 86, No. 212 / Friday, November 5, 2021 / Proposed Rules List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. The Proposed Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows: (b) Affected ADs None. (c) Applicability This AD applies to Rolls-Royce Deutschland Ltd & Co KG (RRD) (Type Certificate previously held by Rolls-Royce plc) Trent 1000–AE3, Trent 1000–CE3, Trent 1000–D3, Trent 1000–G3, Trent 1000–H3, Trent 1000–J3, Trent 1000–K3, Trent 1000– L3, Trent 1000–M3, Trent 1000–N3, Trent 1000–P3, Trent 1000–Q3, and Trent 1000–R3 model turbofan engines. (d) Subject Joint Aircraft System Component (JASC) Code 7250, Turbine Section. 2. The FAA amends § 39.13 by adding the following new airworthiness directive: (e) Unsafe Condition This AD was prompted by reports of high levels of wear on the seal fins on a small number of certain high-pressure turbine triple seals. The FAA is issuing this AD to ensure cooling airflow restoration to the intermediate-pressure turbine (IPT) disk rim during cruise by deactivating the modulated air system (MAS). The unsafe condition, if not addressed, could result in a temperature increase at the IPT disk rim when the MAS is active during cruise, resulting in failure of the IPT disk, loss of engine thrust control, and loss of the airplane. Rolls-Royce Deutschland Ltd & Co KG (Type Certificate previously held by RollsRoyce plc): Docket No. FAA–2021–0662; Project Identifier MCAI–2021–00031–E. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (h) Alternative Methods of Compliance (AMOCs) (i) Related Information PART 39—AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: ■ Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 [Amended] ■ jspears on DSK121TN23PROD with PROPOSALS1 (a) Comments Due Date The FAA must receive comments on this airworthiness directive (AD) by December 20, 2021. (1) The Manager, ECO Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ECO Branch, send it to the attention of the person identified in paragraph (i)(1) of this AD. Information may be emailed to: ANE-AD-AMOC@faa.gov. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/ certificate holding district office. VerDate Sep<11>2014 17:04 Nov 04, 2021 Jkt 256001 (1) For more information about this AD, contact Kevin Clark, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: (781) 238–7088; fax: (781) 238–7199; email: kevin.m.clark@faa.gov. (2) Refer to European Union Aviation Safety Agency (EASA) AD 2021–0009, dated January 8, 2021, for more information. You may examine the EASA AD in the AD docket at https://www.regulations.gov by searching for and locating it in Docket No. FAA–2021– 0662. (3) For service information identified in this AD, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, DE24 8BJ, United Kingdom; phone: +44 (0)1332 242424; fax: +44 (0)1332 249936; website: PO 00000 Frm 00005 Fmt 4702 Sfmt 9990 (g) Required Actions Within the compliance time specified in figure 1 to paragraph (g) of this AD, deactivate the MAS control valves using the Accomplishment Instructions, paragraphs 3.A.(6) and 3.A.(7), of Rolls-Royce Alert NonModification Service Bulletin Trent 1000 75– AK642, Initial Issue, dated November 30, 2020. Note 1 to paragraph (g): Deactivation of the MAS control valves on an engine required by paragraph (g) of this AD changes the engine to an approved configuration that will produce engine indicating and crew alerting system (EICAS) status messages ‘‘ENG MAS VALVE L/R’’ and ‘‘ENG MAS SYS TEST L/ R.’’ Since MAS is purposely disabled after compliance with paragraph (g) of this AD, these status messages do not indicate inoperative (failed) equipment and, consequently, the operator’s existing FAAapproved minimum equipment list (MEL) instructions and limitations, including the 120-day operation limitation, do not apply. Note 2 to paragraph (g): Deactivation of the MAS control valves on an engine as required by paragraph (g) of this AD does not produce the EICAS status message ‘‘ENG MAS VALVE SENSOR L/R.’’ Consequently, when this EICAS message displays, it remains indicative of inoperative equipment, even if the MAS has been disabled as required by paragraph (g) of this AD. As a result, the corresponding MEL instructions and limitations apply whenever the EICAS status message ‘‘ENG MAS VALVE SENSOR L/R’’ is displayed. https://www.rolls-royce.com/contact-us.aspx. You may view this referenced 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. Issued on October 29, 2021. Lance T. Gant, Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2021–24056 Filed 11–4–21; 8:45 am] BILLING CODE 4910–13–P E:\FR\FM\05NOP1.SGM 05NOP1 EP05NO21.033</GPH> For the reasons discussed above, I certify this proposed regulation: (1) Is not a ‘‘significant regulatory action’’ under Executive Order 12866, (2) Would not affect intrastate aviation in Alaska, and (3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. 61085

Agencies

[Federal Register Volume 86, Number 212 (Friday, November 5, 2021)]
[Proposed Rules]
[Pages 61083-61085]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-24056]



[[Page 61083]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0662; Project Identifier MCAI-2021-00031-E]
RIN 2120-AA64


Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG 
(Type Certificate Previously Held by Rolls-Royce plc) Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA is revising a notice of proposed rulemaking (NPRM) 
that applied to certain Rolls-Royce Deutschland Ltd & Co KG (RRD) Trent 
1000 model turbofan engines. This action revises the NPRM by reopening 
the comment period because the NPRM was placed in incorrect Docket No. 
FAA-2021-0637 instead of Docket No. FAA-2021-0662. The FAA is proposing 
this airworthiness directive (AD) to address the unsafe condition on 
these products. Since commenters experienced difficulties in commenting 
on the NPRM, the FAA is requesting comments on this SNPRM.

DATES: The FAA must receive comments on this SNPRM by December 20, 
2021.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this SNPRM, contact Rolls-
Royce plc, Corporate Communications, P.O. Box 31, Derby, DE24 8BJ, 
United Kingdom; phone: +44 (0)1332 242424; fax: +44 (0)1332 249936; 
website: https://www.rolls-royce.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.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0662; 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 SNPRM, the 
mandatory continuing airworthiness information (MCAI), any comments 
received, and other information. The street address for Docket 
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Kevin Clark, Aviation Safety Engineer, 
ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: 
(781) 238-7088; fax: (781) 238-7199; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2021-0662; Project Identifier 
MCAI-2021-00031-E'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the proposal, explain the 
reason for any recommended change, and include supporting data. The FAA 
will consider all comments received by the closing date and may amend 
this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact received about this proposed AD.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this SNPRM contain 
commercial or financial information that is customarily treated as 
private, that you actually treat as private, and that is relevant or 
responsive to this SNPRM, it is important that you clearly designate 
the submitted comments as CBI. Please mark each page of your submission 
containing CBI as ``PROPIN.'' The FAA will treat such marked 
submissions as confidential under the FOIA, and they will not be placed 
in the public docket of this SNPRM. Submissions containing CBI should 
be sent to Kevin Clark, Aviation Safety Engineer, ECO Branch, FAA, 1200 
District Avenue, Burlington, MA 01803. Any commentary that the FAA 
receives which is not specifically designated as CBI will be placed in 
the public docket for this rulemaking.

Background

    The FAA issued an NPRM to amend 14 CFR part 39 by adding an AD that 
would apply to RRD Trent 1000-AE3, Trent 1000-CE3, Trent 1000-D3, Trent 
1000-G3, Trent 1000-H3, Trent 1000-J3, Trent 1000-K3, Trent 1000-L3, 
Trent 1000-M3, Trent 1000-N3, Trent 1000-P3, Trent 1000-Q3, and Trent 
1000-R3 model turbofan engines. The NPRM published in the Federal 
Register on August 13, 2021 (86 FR 44655). The NPRM was prompted by 
reports of high levels of wear on the seal fins on a small number of 
certain high-pressure turbine triple seals. In the NPRM, the FAA 
proposed to require manual deactivation of the modulated air system 
(MAS) control valves.
    The European Union Aviation Safety Agency (EASA), which is the 
Technical Agent for the Member States of the European Community, has 
issued EASA AD 2021-0009, dated January 8, 2021 (referred to after this 
as ``the MCAI''), to address the unsafe condition on these products. 
The MCAI states:

    The Modulated Air System (MAS) optimises cooling air, extracted 
from the compressor, where full flow is not required at cruise 
conditions. It is only active during cruise. Recently, occurrences 
have been reported of finding high levels of wear on the seal fins 
on a small number of high pressure turbine triple seals, Part Number 
FW34485. The effect on the secondary air system was conservatively 
assessed due to the resultant increased turbine cooling air leakage, 
which changes the cooling flow around the intermediate pressure (IP) 
turbine disc.
    This condition, if not corrected, could lead to temperature 
increase at the IP turbine disc rim when the MAS is active, possibly 
resulting in IP turbine disc failure and high energy debris release, 
with consequent damage to, and reduced control of, the aeroplane.
    To address this potential unsafe condition, Rolls-Royce has 
issued the NMSB, providing instructions to manually `lock-out' 
(deactivate) the MAS control valves.
    For the reason described above, this [EASA] AD requires to 
deactivate the MAS control valves. This [EASA] AD also specifies 
that the Master Minimum Equipment List (MMEL) item for `MAS 
inoperative', which has a limit of 120 days, does not apply when the 
system is manually deactivated.

    You may obtain further information by examining the MCAI in the AD

[[Page 61084]]

docket at https://www.regulations.gov by searching for and locating 
Docket No. FAA-2021-0662.

Actions Since the NPRM Was Issued

    Since the FAA issued the NPRM, the FAA determined the NPRM was 
inadvertently placed in incorrect Docket No. FAA-2021-0637 instead of 
Docket No. FAA-2021-0662. The FAA received information that the public 
had difficulty commenting on the NPRM.

Comments

    The FAA received comments on the NPRM from two commenters. The 
following presents the comments received on the NPRM and the FAA's 
response to each comment.

Request To Revise the Unsafe Condition

    The Boeing Company (Boeing) requested the FAA revise paragraph (e), 
Unsafe Condition, of the NPRM to accurately reflect the effect of the 
AD on the unsafe condition. Boeing suggested revising paragraph (e) to 
state ``This AD was prompted by reports of high levels of wear on the 
seal fins on a small number of certain high-pressure turbine (HPT) 
triple seals. This condition, if not addressed, could lead to 
temperature increase at the Intermediate Pressure (IP) turbine disk rim 
when the Modulated Air System (MAS) is active during cruise, possibly 
resulting in failure of the IP turbine disk, loss of engine thrust 
control, and loss of the airplane. The FAA is issuing this AD to 
restore cooling airflow to the IP turbine disk rim during cruise by 
deactivating MAS.'' Boeing reasoned that the AD action to deactivate 
the MAS does not prevent wear on the HPT triple seal fins. Deactivating 
the MAS restores cooling airflow to the intermediate-pressure turbine 
(IPT) disk rim during cruise.
    The FAA updated paragraph (e) of this proposed AD by stating, 
``This AD was prompted by reports of high levels of wear on the seal 
fins on a small number of certain high-pressure turbine triple seals. 
The FAA is issuing this AD to ensure cooling airflow restoration to the 
intermediate-pressure turbine (IPT) disk rim during cruise by 
deactivating the modulated air system (MAS). The unsafe condition, if 
not addressed, could result in a temperature increase at the IPT disk 
rim, when the MAS is active during cruise, resulting in failure of the 
IPT disk, loss of engine thrust control, and loss of the airplane.''

Request To Correct Part Number Reference

    Rolls-Royce notified the FAA that the preamble of the NPRM 
incorrectly identifies the HPT triple seal part number (P/N) as FW3448, 
whereas the correct identification is FW34485.
    The FAA agrees and has revised the Background section of this 
proposed AD by correcting the reference to the HPT triple seal P/N from 
FW3448 to FW34485.

FAA's Determination

    This product has been approved by EASA and is approved for 
operation in the United States. Pursuant to the FAA's bilateral 
agreement with the European Community, EASA has notified the FAA of the 
unsafe condition described in the MCAI and service information. The FAA 
is proposing this AD because the agency evaluated all the relevant 
information provided by EASA and determined the unsafe condition 
described previously is likely to exist or develop in other products of 
the same type design. The public had difficulty commenting on the NPRM. 
As a result, the FAA has determined that it is necessary to reopen the 
comment period to provide opportunity for the public to comment on this 
SNPRM.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Rolls-Royce Alert Non-Modification Service 
Bulletin Trent 1000 75-AK642, Initial Issue, dated November 30, 2020. 
The service information specifies procedures for deactivating the MAS 
control valves. This service information is reasonably available 
because the interested parties have access to it through their normal 
course of business or by the means identified in ADDRESSES.

Proposed Requirements in This SNPRM

    This proposed AD would require manual deactivation of the MAS 
control valves. Manual deactivation of the MAS control valves changes 
the engine to an approved configuration that will produce engine 
indicating and crew alerting system (EICAS) status messages that do not 
indicate inoperative (failed) equipment. Consequently, when these 
messages are displayed, the operator's existing FAA-approved minimum 
equipment list (MEL) instructions and limitations, including the 120-
day operation limitation, do not apply.

Interim Action

    The FAA considers this proposed AD would be an interim action. If 
final action is later identified, the FAA might consider additional 
rulemaking.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 4 engines installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Deactivate the MAS control valves.....  2 work-hours x $85 per                $0            $170            $680
                                         hour = $170.
----------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    The FAA determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or on the distribution 
of power and responsibilities among the various levels of government.

[[Page 61085]]

    For the reasons discussed above, I certify this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

Rolls-Royce Deutschland Ltd & Co KG (Type Certificate previously 
held by Rolls-Royce plc): Docket No. FAA-2021-0662; Project 
Identifier MCAI-2021-00031-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by December 20, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Rolls-Royce Deutschland Ltd & Co KG (RRD) 
(Type Certificate previously held by Rolls-Royce plc) Trent 1000-
AE3, Trent 1000-CE3, Trent 1000-D3, Trent 1000-G3, Trent 1000-H3, 
Trent 1000-J3, Trent 1000-K3, Trent 1000-L3, Trent 1000-M3, Trent 
1000-N3, Trent 1000-P3, Trent 1000-Q3, and Trent 1000-R3 model 
turbofan engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7250, Turbine 
Section.

(e) Unsafe Condition

    This AD was prompted by reports of high levels of wear on the 
seal fins on a small number of certain high-pressure turbine triple 
seals. The FAA is issuing this AD to ensure cooling airflow 
restoration to the intermediate-pressure turbine (IPT) disk rim 
during cruise by deactivating the modulated air system (MAS). The 
unsafe condition, if not addressed, could result in a temperature 
increase at the IPT disk rim when the MAS is active during cruise, 
resulting in failure of the IPT disk, loss of engine thrust control, 
and loss of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    Within the compliance time specified in figure 1 to paragraph 
(g) of this AD, deactivate the MAS control valves using the 
Accomplishment Instructions, paragraphs 3.A.(6) and 3.A.(7), of 
Rolls-Royce Alert Non-Modification Service Bulletin Trent 1000 75-
AK642, Initial Issue, dated November 30, 2020.
    Note 1 to paragraph (g): Deactivation of the MAS control valves 
on an engine required by paragraph (g) of this AD changes the engine 
to an approved configuration that will produce engine indicating and 
crew alerting system (EICAS) status messages ``ENG MAS VALVE L/R'' 
and ``ENG MAS SYS TEST L/R.'' Since MAS is purposely disabled after 
compliance with paragraph (g) of this AD, these status messages do 
not indicate inoperative (failed) equipment and, consequently, the 
operator's existing FAA-approved minimum equipment list (MEL) 
instructions and limitations, including the 120-day operation 
limitation, do not apply.
    Note 2 to paragraph (g): Deactivation of the MAS control valves 
on an engine as required by paragraph (g) of this AD does not 
produce the EICAS status message ``ENG MAS VALVE SENSOR L/R.'' 
Consequently, when this EICAS message displays, it remains 
indicative of inoperative equipment, even if the MAS has been 
disabled as required by paragraph (g) of this AD. As a result, the 
corresponding MEL instructions and limitations apply whenever the 
EICAS status message ``ENG MAS VALVE SENSOR L/R'' is displayed.
[GRAPHIC] [TIFF OMITTED] TP05NO21.033

(h) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, ECO Branch, FAA, has the authority to approve 
AMOCs for this AD, if requested using the procedures found in 14 CFR 
39.19. In accordance with 14 CFR 39.19, send your request to your 
principal inspector or local Flight Standards District Office, as 
appropriate. If sending information directly to the manager of the 
ECO Branch, send it to the attention of the person identified in 
paragraph (i)(1) of this AD. Information may be emailed to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(i) Related Information

    (1) For more information about this AD, contact Kevin Clark, 
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: (781) 238-7088; fax: (781) 238-7199; 
email: [email protected].
    (2) Refer to European Union Aviation Safety Agency (EASA) AD 
2021-0009, dated January 8, 2021, for more information. You may 
examine the EASA AD in the AD docket at https://www.regulations.gov 
by searching for and locating it in Docket No. FAA-2021-0662.
    (3) For service information identified in this AD, contact 
Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, DE24 
8BJ, United Kingdom; phone: +44 (0)1332 242424; fax: +44 (0)1332 
249936; website: https://www.rolls-royce.com/contact-us.aspx. You 
may view this referenced 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.

    Issued on October 29, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-24056 Filed 11-4-21; 8:45 am]
BILLING CODE 4910-13-P

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