Document ID: FAA-2022-0516-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2022-05-27T04:00Z

[Federal Register Volume 87, Number 103 (Friday, May 27, 2022)]
[Proposed Rules]
[Pages 32098-32103]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-11346]

 ========================================================================
 Proposed Rules
                                                 Federal Register
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 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 87, No. 103 / Friday, May 27, 2022 / Proposed 
Rules  

[[Page 32098]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0516; Project Identifier AD-2022-00262-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all General Electric Company (GE) GE90-110B1 and GE90-115B model 
turbofan engines and certain GE90-76B, GE90-85B, GE90-90B, and GE90-94B 
model turbofan engines. This proposed AD was prompted by the detection 
of melt-related freckles in the forgings and billets, which may reduce 
the life of certain rotating compressor discharge pressure (CDP) high-
pressure turbine (HPT) seals (rotating CDP seals), interstage HPT rotor 
seals, and HPT rotor stage 2 disks. This proposed AD would require 
revising the airworthiness limitations section (ALS) of the applicable 
GE90-100 Engine Manual (EM) and the operator's existing approved 
maintenance program or inspection program, as applicable, to 
incorporate reduced life limits for these parts. This proposed AD would 
also require the removal and replacement of certain interstage HPT 
rotor seals, identified by serial number (S/N), installed on GE90-76B, 
GE90-85B, GE90-90B, and GE90-94B model turbofan engines. The FAA is 
proposing this AD to address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by July 11, 
2022.

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 NPRM, contact General 
Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 
552-3272; email: [email protected]; website: https://www.ge.com. 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 (817) 222-5110.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2022-0516; 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 NPRM, any comments 
received, and other information. The street address for Docket 
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Alexei Marqueen, Aviation Safety 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: (781) 238-7178; 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-2022-0516; Project Identifier 
AD-2022-00262-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 NPRM.

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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to 
Alexei Marqueen, 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 was notified by the engine manufacturer of the detection of 
melt-related freckles in the forgings and billets, which may reduce the 
life of certain rotating CDP seals, interstage HPT rotor seals, and HPT 
rotor stage 2 disks on GE90-110B1 and GE90-115B model turbofan engines 
and may reduce the life of certain interstage HPT rotor seals on GE90-
76B, GE90-85B, GE90-90B, and GE90-94B model turbofan engines. The 
manufacturer's investigation determined that, as a result of such 
freckles forming in the forgings and billets, certain rotating CDP 
seals, interstage HPT rotor seals, and HPT rotor stage 2 disks (life-
limited parts (LLPs)) may have undetected subsurface anomalies that 
developed during the manufacturing process,

[[Page 32099]]

resulting in reduced material properties and a lower fatigue life 
capability. Reduced material properties may cause premature LLP 
fracture, which could result in uncontained debris release. As a result 
of its investigation, the manufacturer determined the need to reduce 
the life limits of certain LLPs. To reflect these reduced life limits, 
the manufacturer revised the ALS of the affected GE90-100 EMs. 
Additionally, the manufacturer published service information that 
specifies procedures for the removal and replacement of certain 
interstage HPT rotor seals installed on GE90-76B, GE90-85B, GE90-90B, 
and GE90-94B model turbofan engines. This condition, if not addressed, 
could result in uncontained debris release, damage to the engine, and 
damage to the airplane.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Related Service Information

    The FAA reviewed GE GE90-100 Service Bulletin (SB) 72-0851 R00, 
dated August 17, 2021. This SB provides the reduced life limits for 
certain LLPs. The FAA also reviewed GE GE90 SB 72-1211 R00, dated March 
9, 2022. This SB describes procedures for removing and replacing 
certain interstage HPT rotor seals.

Proposed AD Requirements in This NPRM

    This proposed AD would require revising the ALS of the applicable 
GE90-100 EM and the operator's existing approved maintenance program or 
inspection program, as applicable, to incorporate reduced life limits 
for certain LLPs. This proposed AD would also require the removal and 
replacement of certain interstage HPT rotor seals.

Differences Between This Proposed AD and the Service Information

    GE90-100 SB 72-0851 R00, dated August 17, 2021, uses the term ``HPT 
rotor interstage seals,'' while this proposed AD uses the term 
``interstage HPT rotor seals.''

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 248 engines installed on airplanes of U.S. registry. The FAA 
estimates that zero engines installed on airplanes of U.S. registry 
would require replacement of the interstage HPT rotor seal.
    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
----------------------------------------------------------------------------------------------------------------
Revise ALS of EM and the operator's     1 work-hour x $85 per                 $0             $85         $21,080
 existing approved maintenance program   hour = $85.
 or inspection program.
Replace interstage HPT rotor seal.....  1,500 work-hours x $85           286,331         413,831               0
                                         per hour = $127,500.
----------------------------------------------------------------------------------------------------------------

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.
    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:

General Electric Company: Docket No. FAA-2022-0516; Project 
Identifier AD-2022-00262-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by July 11, 2022.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to:
    (1) General Electric Company (GE) GE90-110B1 and GE90-115B model 
turbofan engines; and
    (2) GE GE90-76B, GE90-85B, GE90-90B, and GE90-94B model turbofan 
engines with an installed interstage high-pressure turbine (HPT) 
rotor seal with part number (P/N) 2629M47P01 and serial number (S/N) 
NCU5430D.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7230, Turbine Engine 
Compressor Section, and JASC Code 7250, Turbine Section.

(e) Unsafe Condition

    This AD was prompted by the detection of melt-related freckles 
in the forgings and

[[Page 32100]]

billets, which may reduce the life of certain rotating compressor 
discharge pressure (CDP) HPT seals (rotating CDP seal), interstage 
HPT rotor seals, and HPT rotor stage 2 disks. The FAA is issuing 
this AD to prevent failure of the rotating CDP seal, interstage HPT 
rotor seal, and HPT rotor stage 2 disk. The unsafe condition, if not 
addressed, could result in uncontained debris release, damage to the 
engine, and damage to the airplane.

(f) Compliance

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

(g) Required Actions

    (1) For affected GE90-110B1 and GE90-115B model turbofan 
engines, within 90 days after the effective date of this AD, revise 
the airworthiness limitations section (ALS) of the existing GE90-100 
Engine Manual (EM) and the operator's existing approved maintenance 
program or inspection program, as applicable, by inserting the 
following information:
    (i) For rotating CDP seal P/N 2479M03P01, insert the information 
in Table 1 to paragraph (g)(1)(i) of this AD.
BILLING CODE 4910-13-P
[GRAPHIC] [TIFF OMITTED] TP27MY22.000

    (ii) For interstage HPT rotor seal P/N 2505M72P01, insert the 
information in Table 2 to paragraph (g)(1)(ii) of this AD.

[[Page 32101]]

[GRAPHIC] [TIFF OMITTED] TP27MY22.001

    (iii) For HPT rotor stage 2 disk P/N 2505M73P03, insert the 
information in Table 3 to paragraph (g)(1)(iii) of this AD.

[[Page 32102]]

[GRAPHIC] [TIFF OMITTED] TP27MY22.002

    (2) For affected GE90-76B, GE90-85B, GE90-90B, and GE90-94B 
model turbofan engines, before the interstage HPT rotor seal, P/N 
2629M47P01 and S/N NCU5430D, accumulates 7,400 cycles since new, 
remove the affected interstage HPT rotor seal from service and 
replace with a part eligible for installation.

(h) Definitions

    For the purpose of this AD, a ``part eligible for installation'' 
is any interstage HPT rotor seal that does not have P/N 2629M47P01 
and S/N NCU5430D.

(i) 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 
certification office, send it to the attention of the person 
identified in paragraph (j)(1) of this AD and email 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.

(j) Related Information

    (1) For more information about this AD, contact Alexei Marqueen, 
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: (781) 238-7178; email: 
[email protected].

[[Page 32103]]

    (2) For service information identified in this AD, contact 
General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: [email protected]; website: 
https://www.ge.com. 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 (817) 222-
5110.

    Issued on May 5, 2022.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2022-11346 Filed 5-26-22; 8:45 am]
BILLING CODE 4910-13-C