Airworthiness Directives; General Electric Company Turbofan Engines

[Federal Register Volume 87, Number 30 (Monday, February 14, 2022)]
[Rules and Regulations]
[Pages 8178-8180]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-03040]



[[Page 8178]]

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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; 
Amendment 39-21933; AD 2022-03-16]
RIN 2120-AA64


Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain General Electric Company (GE) GEnx-1B and GEnx-2B model 
turbofan engines. This AD was prompted by the manufacturer's report of 
two findings of sheared compressor discharge pressure (CDP) bolts 
during engine shop visits. This AD requires 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 AD requires operators to reassemble the CDP 
bolted joint using a specific torque wrench. The FAA is issuing this AD 
to address the unsafe condition on these products.

DATES: This AD is effective March 21, 2022.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of March 21, 
2022.

ADDRESSES: For service information identified in this final rule, 
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 (817) 222-5110. It is 
also available at https://www.regulations.gov by searching for and 
locating Docket No. FAA-2021-0831.

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 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 W12-140, 1200 New Jersey Avenue 
SE, Washington, DC 20590.

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:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain GE GEnx-1B and 
GEnx-2B model turbofan engines. The NPRM published in the Federal 
Register on October 28, 2021 (86 FR 59667). The NPRM was prompted by a 
report from 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. In the 
NPRM, the FAA proposed to 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, the NPRM also proposed to 
require operators to reassemble the CDP bolted joint using a 11C4888P01 
torque wrench. The FAA is issuing this AD to address the unsafe 
condition on these products.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from four commenters. The commenters were 
American Airlines (American), The Boeing Company (Boeing), GE Aviation, 
and United Airlines Engineering (UAL Engineering). The following 
presents the comments received on the NPRM and the FAA's response to 
each comment.

Request To Add Engine Serial Numbers to Applicability Paragraph

    American requested that the FAA clarify paragraph (c), 
Applicability, by adding the affected engine serial numbers (S/Ns). 
American explained that operators do not have visibility to the engines 
that were assembled or reassembled by GE with the 11C4525P01 torque 
fixture, or engines that were assembled with the 11C4629P01 torque 
wrench. American noted that due to this lack of visibility, operators 
will need to rely on GE to provide the affected engine S/Ns, either in 
GEnx-1B Service Bulletin (SB) 72-0495 R00, dated May 11, 2021 (GEnx-1B 
SB 72-0495) or in response to an inquiry, which would place an 
excessive burden on the operators.
    The FAA disagrees with adding engine S/Ns to the Applicability 
paragraph of this AD. According to GE, each maintenance, repair and 
overhaul (MRO) shop will have a record of what date the new 11C4888P01 
torque wrench was implemented for use, and any CDP bolted joint 
reassembled at an engine shop visit prior to that implementation date 
would have used the prior 11C4525P01 torque fixture. Thus, for engines 
that have had an engine shop visit, each operator will be able to 
determine if their engine is affected based on the date of the last 
engine shop visit and the date that the particular MRO shop implemented 
the new tool. For engines that have not had an engine shop visit, 
Paragraph 1.A, Table A of GEnx-1B SB 72-0495 and Paragraph 1.A, Table A 
of GE GEnx-2B SB 72-0433 R00, dated May 11, 2021 define which engine S/
Ns are affected based on production records.

Request To Add Clarifying Language to Required Actions

    GE Aviation requested that the FAA update the language in paragraph 
(g)(2) of this AD to incorporate a reference to the terminating action 
contained in paragraph (h) of this AD. GE supported its request for 
change by explaining the additional reference will ensure clear 
understanding of the requirements.
    The FAA disagrees with updating paragraph (g)(2) of this AD to 
incorporate a reference to the terminating action in paragraph (h) of 
this AD. Referencing paragraph (h) within paragraph (g)(2) is 
unnecessary.

Request To Add Language Requiring Accomplishment of Terminating Action

    UAL Engineering requested that the FAA incorporate the terminating 
action in paragraph (h) of this AD as a requirement in paragraph (g)(3) 
of this

[[Page 8179]]

AD. UAL Engineering explained that requiring the terminating action 
within paragraph (g)(3) of this AD would eliminate any ambiguity 
involving the reassembly of the CDP bolted joint, which could 
potentially lead to the use of a non-conforming tool and additional 
repetitive inspections.
    The FAA disagrees with revising the required action as proposed by 
UAL Engineering. MRO shops no longer use the 11C4525P01 torque fixture. 
All MRO shops have implemented the use of the updated 11C4888P01 torque 
wrench. Therefore, if a piece part inspection is required pursuant to 
paragraph (g)(3) of this AD, the CDP bolted joint will be reassembled 
with the updated 11C4888P01 torque wrench. The non-conforming tool will 
not be used, and therefore will not drive any additional repetitive 
inspections after a reassembly is performed following a piece part 
inspection.

Support for the AD

    Boeing expressed support for the AD as written.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this 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. None of the changes will 
increase the economic burden on any operator.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed GE GEnx-1B SB 72-0495 R00, dated May 11, 2021 (GE 
GEnx-1B SB 72-0495) and GE GEnx-2B SB 72-0433 R00, dated May 11, 2021 
(GEnx-2B SB 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.

Costs of Compliance

    The FAA estimates that this AD affects 320 engines installed on 
airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this 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.
----------------------------------------------------------------------------------------------------------------

    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 CPD 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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will 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 Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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.

[[Page 8180]]

Sec.  39.13  [Amended]

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

2022-03-16 General Electric Company: Amendment 39-21933; Docket No. 
FAA-2021-0831; Project Identifier AD-2021-00712-E.

(a) Effective Date

    This airworthiness directive (AD) is effective March 21, 2022.

(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 of the stages 6-10 
compressor rotor spool, CDP seal, and high-pressure turbine rotor 
stage 1 disk in accordance with the Instructions for Continued 
Airworthiness.

(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 
paragraph (k) 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

    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].

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) General Electric Company (GE) GEnx-1B Service Bulletin (SB) 
72-0495 R00, dated May 11, 2021.
    (ii) GE GEnx-2B SB 72-0433 R00, dated May 11, 2021.
    (3) For GE 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.
    (4) You may view this service information at 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.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email: [email protected], or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on January 25, 2022.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2022-03040 Filed 2-11-22; 8:45 am]
BILLING CODE 4910-13-P

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