Document ID: FAA-2021-0831-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2021-10-28T04:00Z

[Federal Register Volume 86, Number 206 (Thursday, October 28, 2021)]
[Proposed Rules]
[Pages 59667-59670]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-23237]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0831; Project Identifier AD-2021-00712-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain General Electric Company (GE) GEnx-1B and GEnx-2B model 
turbofan engines. This proposed AD was prompted by the manufacturer's 
report of two findings of sheared compressor discharge pressure (CDP) 
bolts during engine shop visits. This proposed AD would require initial 
and repetitive inspections of the CDP bolted joint and, depending on 
the findings, a piece part inspection of the stages 6-10 compressor 
rotor spool, CDP seal, and high-pressure turbine (HPT) rotor stage 1 
disk. As a terminating action, this proposed AD would require operators 
to reassemble the CDP bolted joint using a specific torque wrench. The 
FAA is proposing this AD to address the unsafe condition on these 
products.

[[Page 59668]]

DATES: The FAA must receive comments on this proposed AD by December 
13, 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 NPRM, contact General 
Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 
552-3272; email: [email protected]; website: 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 (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-2021-0831; 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; 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-2021-0831; Project Identifier 
AD-2021-00712-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 manufacturer of two findings of sheared 
CDP bolts at engine shop visits during disassembly of the CDP bolted 
joint on GEnx-1B70/75/P2 and GEnx-2B67/P model turbofan engines. 
Subsequent investigation by the manufacturer determined that the 
fracture and liberation of the CDP bolts was caused by the inadvertent 
over-torque condition of the bolts during assembly and reassembly with 
a 11C4525P01 torque fixture or during assembly with a 11C4629P01 torque 
wrench. In one finding, the fractured CDP bolt caused damage to the 
stages 6-10 compressor rotor spool, CDP seal, and HPT rotor stage 1 
disk. This condition, if not addressed, could result in 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 Under 1 CFR Part 51

    The FAA reviewed GE GEnx-1B Service Bulletin (SB) 72-0495 R00, 
dated May 11, 2021, (GEnx-1B SB 72-0495) and GE GEnx-2B SB 72-0433 R00, 
dated May 11, 2021 (GEnx-2B S/B 72-0433). GEnx-1B SB 72-0495 describes 
procedures for the inspection of the CDP bolted joint components on 
GEnx-1B model turbofan engines. GEnx-2B SB 72-0433 describes procedures 
for the inspection of the CDP bolted joint components on GEnx-2B model 
turbofan engines. 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 AD Requirements in This NPRM

    This proposed AD would require initial and repetitive inspections 
of the CDP bolted joint and, depending on the findings, a piece part 
inspection of the stages 6-10 compressor rotor spool, CDP seal, and HPT 
rotor stage 1 disk. As a terminating action, this proposed AD would 
require operators to reassemble the CDP bolted joint using a 11C4888P01 
torque wrench.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 320 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
----------------------------------------------------------------------------------------------------------------
Inspection of CDP bolted joint........  1 work-hour x $85 per                 $0             $85         $27,200
                                         hour = $85.
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[[Page 59669]]

    The FAA estimates the following costs to do any necessary 
additional inspections that would be required based on the results of 
the proposed inspection. The agency has no way of determining the 
number of aircraft that might need these inspections.

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Piece part inspection of stages 6-10            56 work-hours x $85 per hour =                $0          $4,760
 compressor rotor spool.                         $4,760.
Piece part inspection of CDP seal.............  22 work-hours x $85 per hour =                 0           1,870
                                                 $1,870.
Piece part inspection of HPT rotor stage 1      59 work-hours x $85 per hour =                 0           5,015
 disk.                                           $5,015.
----------------------------------------------------------------------------------------------------------------

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-2021-0831; Project 
Identifier AD-2021-00712-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by December 13, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) GEnx-1B64, 
GEnx-1B64/P1, GEnx-1B64/P2, GEnx-1B67, GEnx-1B67/P1, GEnx-1B67/P2, 
GEnx-1B70, GEnx-1B70/75/P1, GEnx-1B70/75/P2, GEnx-1B70/P1, GEnx-
1B70/P2, GEnx-1B70C/P1, GEnx-1B70C/P2, GEnx-1B74/75/P1, GEnx-1B74/
75/P2, GEnx-1B76/P2, GEnx-1B76A/P2, GEnx-2B67, GEnx-2B67B, and GEnx-
2B67/P model turbofan engines with a compressor discharge pressure 
(CDP) bolted joint assembled or reassembled with the 11C4525P01 
torque fixture or assembled with the 11C4629P01 torque wrench.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by a report from the manufacturer of two 
findings of sheared CDP bolts during engine shop visits. The FAA is 
issuing this AD to prevent fracture of the CDP bolt. The unsafe 
condition, if not addressed, could result in 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) At the next engine shop visit after the effective date of 
this AD, perform an inspection of the CDP bolted joint for fractured 
or missing material using the Accomplishment Instructions, paragraph 
3.A.(2) of GE GEnx-1B Service Bulletin (SB) 72-0495 R00, dated May 
11, 2021 (GEnx-1B SB 72-0495) (for GEnx-1B models) or Accomplishment 
Instructions, paragraph 3.A.(2) of GE GEnx-2B SB 72-0433 R00, dated 
May 11, 2021, (GEnx-2B SB 72-0433) (for GEnx-2B models).
    (2) Repeat the inspection required by paragraph (g)(1) of this 
AD at every engine shop visit.
    (3) If a fractured or missing bolt or nut is found during any 
inspection required by paragraph (g)(1) or (2) of this AD, before 
further flight, perform piece part inspections in accordance with 
the Instructions for Continued Airworthiness of the stages 6-10 
compressor rotor spool, CDP seal, and high-pressure turbine rotor 
stage 1 disk.

(h) Terminating Action

    As terminating action to the repetitive inspections required by 
paragraph (g)(2) of this AD, reassemble the CDP bolted joint using 
the 11C4888P01 torque wrench, in accordance with the Accomplishment 
Instructions, paragraph 3.B.(1) of GEnx-1B SB 72-0495 (for GEnx-1B 
models) or the Accomplishment Instructions, paragraph 3.B.(1) of 
GEnx-2B SB 72-0433 (for GEnx-2B models).

(i) Definition

    For the purpose of this AD, an ``engine shop visit'' is the 
induction of an engine into the shop for maintenance involving a 
module exposure in which the mid fan shaft removal exposes the CDP 
bolted joint.

(j) 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

[[Page 59670]]

paragraph (k)(1) of this AD. You may email your request 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.

(k) 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; fax: (781) 238-7199; 
email: [email protected].
    (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: 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 
(781) 238-7759.

    Issued on September 21, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.

[FR Doc. 2021-23237 Filed 10-27-21; 8:45 am]
BILLING CODE 4910-13-P