Proposed Rule2025-10332
Airworthiness Directives; Pratt & Whitney Division Engines
Primary source
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Published
June 6, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for certain Pratt & Whitney Division (PW) Model PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines. This proposed AD was prompted by an analysis of an event involving an International Aero Engines, LLC (IAE LLC) Model PW1127GA-JM engine, which experienced a high-pressure compressor (HPC) 7th-stage integrally bladed rotor (IBR-7) separation that resulted in an aborted takeoff. This proposed AD would require repetitive angle ultrasonic scan inspections (AUSIs) of the HPC 15th-stage disks, front turbine hubs, high pressure turbine (HPT) 1st-stage air seals, and HPT 2nd-stage hubs for crack indications, and removal from service and replacement if necessary, and for certain serial numbers, removal from service and replacement of the HPT 1st-stage air seal. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 90 Issue 108 (Friday, June 6, 2025)</title>
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[Federal Register Volume 90, Number 108 (Friday, June 6, 2025)]
[Proposed Rules]
[Pages 24085-24087]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-10332]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-0923; Project Identifier AD-2024-00529-E]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney Division 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 Pratt & Whitney Division (PW) Model PW4074, PW4074D,
PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines. This proposed
AD was prompted by an analysis of an event involving an International
Aero Engines, LLC (IAE LLC) Model PW1127GA-JM engine, which experienced
a high-pressure compressor (HPC) 7th-stage integrally bladed rotor
(IBR-7) separation that resulted in an aborted takeoff. This proposed
AD would require repetitive angle ultrasonic scan inspections (AUSIs)
of the HPC 15th-stage disks, front turbine hubs, high pressure turbine
(HPT) 1st-stage air seals, and HPT 2nd-stage hubs for crack
indications, and removal from service and replacement if necessary, and
for certain serial numbers, removal from service and replacement of the
HPT 1st-stage air seal. 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 21,
2025.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: (202) 493-2251.
<bullet> 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.
<bullet> Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-0923; 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.
Material Incorporated by Reference:
<bullet> For PW material identified in this proposed AD, contact
PW, 400 Main Street, East Hartford, CT 06118; phone: (800) 565-0140;
email: <a href="/cdn-cgi/l/email-protection#137b767f632127536361726767647b7a677d766a3d707c7e"><span class="__cf_email__" data-cfemail="e38b868f93d1d7a39391829797948b8a978d869acd808c8e">[email protected]</span></a>; website: <a href="http://connect.prattwhitney.com">connect.prattwhitney.com</a>.
<bullet> You may view this material 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.
FOR FURTHER INFORMATION CONTACT: Molly Sturgis, Aviation Safety
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone:
(562) 627-5373; email: <a href="/cdn-cgi/l/email-protection#ef8280838396c18ec19c9b9a9d88869caf898e8ec1888099"><span class="__cf_email__" data-cfemail="e68b898a8a9fc887c895929394818f95a6808787c8818990">[email protected]</span></a>.
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 the ADDRESSES section. Include ``Docket No. FAA-2025-0923;
Project Identifier AD-2024-00529-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 revise 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
<a href="http://regulations.gov">regulations.gov</a>, 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 Molly
Sturgis, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des
Moines, WA 98198. Any commentary that the FAA receives which is not
specifically designated as CBI will be placed in the public docket for
this rulemaking.
Background
On December 24, 2022, an Airbus Model A320neo airplane powered by
IAE LLC Model PW1127GA-JM engines, experienced a failure of the HPC
IBR-7 that resulted in an engine shutdown and aborted take-off.
Following this event, the manufacturer conducted a records review of
production and field-returned parts and re-evaluated their engineering
analysis methodology. The new analysis found that the failure of the
HPC IBR-7 was caused by a nickel powdered metal anomaly, similar in
nature to an anomaly previously observed. The analysis also concluded
that there is an increased risk of failure for additional nickel
powdered metal parts in certain nickel powdered metal production
campaigns, and these parts are susceptible to failure much earlier than
previously determined. As a result, the FAA is proposing additional
AUSIs for certain affected nickel powdered metal parts and removal from
service of certain affected nickel powdered metal parts. Certain PW
Model PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3
engines are among the products affected by this condition. This
condition, if not addressed, could result in uncontained disk failure,
release of high energy debris, damage to the engine, damage to the
airplane, and possible loss of 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.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed the following service information:
[[Page 24086]]
<bullet> PW Alert Service Bulletin (ASB) PW4G-112-A72-365, Revision
No. 1, dated June 20, 2024, which specifies procedures for performing
repetitive AUSIs on affected HPC 15th-stage disks.
<bullet> PW ASB PW4G-112-A72-366, dated June 20, 2024, which
specifies procedures for performing repetitive AUSIs on affected HPT
1st-stage air seals.
<bullet> PW ASB PW4G-112-A72-367, dated June 20, 2024, which
specifies procedures for performing repetitive AUSIs on affected front
turbine hubs.
<bullet> PW ASB PW4G-112-A72-368, dated June 20, 2024, which
specifies procedures for performing repetitive AUSIs on affected HPT
2nd-stage hubs.
This material is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in the ADDRESSES section.
Proposed AD Requirements in This NPRM
This proposed AD would require repetitive AUSIs of the HPC 15th-
stage disks, front turbine hubs, HPT 1st-stage air seals, and HPT 2nd-
stage hubs for crack indications, and removal from service and
replacement if necessary. This proposed AD would also require, for
certain serial numbers, removal from service and replacement of the HPT
1st-stage air seal.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 124 engines installed on airplanes of U.S. registry. The FAA
estimates that 124 engines will need AUSIs of the HPC 15th-stage disk,
front turbine hub, HPT 2nd-stage hub, and HPT 1st-stage air seal; and 6
engines will need replacement of the HPT 1st-stage air seals.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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AUSI of HPC 15th-stage disk.............. 4 work-hours x $85 per hour $0 $340 $42,160
= $340.
AUSI of front turbine hub................ 5 work-hours x 85 per hour 0 425 52,700
= 425.
AUSI of HPT 2nd-stage hub................ 5 work-hours x 85 per hour 0 425 52,700
= 425.
AUSI of HPT 1st-stage air seal........... 5 work-hours x 85 per hour 0 425 52,700
= 425.
Replace certain HPT 1st-stage air seals 1 work-hours x 85 per hour 763,000 763,085 4,578,510
(6 engines). = 85.
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The FAA estimates the following costs to do any necessary
replacements that would be required based on the results of the
proposed inspection. The agency has no way of determining the number of
engines that might need these replacements:
On-Condition Costs
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Action Labor cost Parts cost Cost per product
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Replace HPC 15th-stage disk.................. 10 work-hours x $85 per hour = $312,000 $312,850
$850.
Replace front turbine hub.................... 10 work-hours x 85 per hour = 910,000 910,850
850.
Replace HPT 2nd-stage hub.................... 10 work-hours x 85 per hour = 816,000 816,850
850.
Replace HPT 1st-stage air seals.............. 10 work-hours x 85 per hour = 763,000 763,850
850.
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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:
Pratt & Whitney Division: Docket No. FAA-2025-0923; Project
Identifier AD-2024-00529-E.
[[Page 24087]]
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by July 21, 2025.
(b) Affected ADs
None.
(c) Applicability
This AD applies to Pratt & Whitney Division (PW) Model PW4074,
PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines.
(d) Subject
Joint Aircraft System Component (JASC) Code 7250, Turbine
Section; 7230, Turbine Engine Compressor Section.
(e) Unsafe Condition
This AD was prompted by an analysis of an event involving an
International Aero Engines, LLC Model PW1127GA-JM engine, which
experienced a high-pressure compressor (HPC) 7th-stage integrally
bladed rotor separation that resulted in an engine shutdown and
aborted takeoff. The FAA is issuing this AD to prevent failure of
the HPC 15th-stage disk, front turbine hub, high pressure turbine
(HPT) 1st-stage air seal, and HPT 2nd-stage hub. The unsafe
condition, if not addressed, could result in uncontained disk
failure, release of high energy debris, damage to the engine, damage
to the airplane, and possible loss of the airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) For HPT 1st-stage air seals with a serial number identified
in table 1 to paragraph (g)(1) of this AD: At the next piece part
opportunity after the effective date of this AD, remove the HPT 1st-
stage air seal from service and replace with a part eligible for
installation.
Table 1 to Paragraph (g)(1)--HPT 1st-Stage Air Seals Affected Serial
Numbers
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Part No.
Serial No. (P/N)
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CKLBME2702................................................... 50L663
CKLBME2703................................................... 50L663
CKLBME2704................................................... 50L663
CKLBME2705................................................... 50L663
CKLBME2711................................................... 50L663
CKLBMS8019................................................... 50L959
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(2) At the next piece part opportunity after the effective date
of this AD, and thereafter at every piece part opportunity, perform
angle ultrasonic scan inspections (AUSIs) of the HPC 15th-stage
disk, front turbine hub, HPT 1st-stage air seal, and HPT 2nd-stage
hub for crack indications in accordance with the applicable service
information specified in paragraph (g)(2)(i) through (iv) of this
AD.
(i) For HPC 15th-stage disks: Accomplishment Instructions,
paragraph 4.A or 4.B., of PW Alert Service Bulletin (ASB) PW4G-112-
A72-365, Revision No. 1, dated June 20, 2024.
(ii) For front turbine hubs: Accomplishment Instructions,
paragraph 4.A or 4.B., of PW ASB PW4G-112-A72-367, dated June 20,
2024.
(iii) For HPT 1st-stage air seals: Accomplishment Instructions,
paragraph 4.A or 4.B., of PW ASB PW4G-112-A72-366, dated June 20,
2024.
(iv) For HPT 2nd-stage hubs: Accomplishment Instructions,
paragraph 4.A or 4.B., of PW ASB PW4G-112-A72-368, dated June 20,
2024.
(3) If during any inspection required by paragraph (g)(2) of
this AD, any crack indication is found, before further flight,
remove the part from service and replace with a part eligible for
installation.
(h) Definitions
For the purposes of this AD:
(1) A ``piece part opportunity'' is one of the conditions
specified in paragraph (h)(1)(i) through (iv).
(i) The HPC 15th-stage disk is removed from the engine and all
blades are removed.
(ii) The front turbine hub is removed from the engine and all
blades are removed.
(iii) The HPT 2nd-stage hub is removed from the engine and all
blades are removed.
(iv) The HPT 1st-stage air seal is fully disassembled from the
engine.
(2) A ``part eligible for installation'' is:
(i) An HPC 15th-stage disk having P/N 51S115, 51S315, 55H615, or
56H015 that has passed the AUSI required by paragraph (g)(2)(i) of
this AD.
(ii) An HPC 15th-stage disk having P/N 51S115 or 56H015 that has
a certificate of conformance that shows compliance with Non-
Destructive Inspection Procedure (NDIP) NDIP-1276.
(iii) An HPC 15th-stage disk having P/N 51S315 or 55H615 that
has a certificate of conformance that shows compliance with NDIP-
1289.
(iv) A front turbine hub having P/N 55L801 or 55L901 that has
passed the AUSI required by paragraph (g)(2)(ii) of this AD.
(v) A front turbine hub having P/N 55L801 that has a certificate
of conformance that shows compliance with NDIP-1273.
(vi) A front turbine hub having P/N 55L901 that has a
certificate of conformance that shows compliance with NDIP-1288.
(vii) An HPT 1st-stage air seal having P/N 50L663 or 50L959 that
has passed the AUSI required by paragraph (g)(2)(iii) of this AD.
(viii) An HPT 1st-stage air seal having P/N 50L663 that has a
certificate of conformance that shows compliance with NDIP-1286.
(ix) An HPT 1st-stage air seal having P/N 50L959 that has a
certificate of conformance that shows compliance with NDIP-1287.
(x) An HPT 2nd-stage hub having P/N 53L202 or 54L802 that has
passed the AUSI required by paragraph (g)(2)(iv) of this AD.
(xi) An HPT 2nd-stage hub having P/N 53L202 that has a
certificate of conformance that shows compliance with NDIP-1274.
(xii) An HPT 2nd-stage hub having P/N 54L802 that has a
certificate of conformance that shows compliance with NDIP-1275.
(xiii) Any HPC 15th-stage disk, front turbine hub, HPT 1st-stage
air seal, or HPT 2nd-stage hub that is new, zero-time, and has
passed an AUSI at new part production.
(i) Alternative Methods of Compliance (AMOCs)
(1) The Manager, AIR-520 Continued Operational Safety 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 AIR-520 Continued
Operational Safety Branch, send it to the attention of the person
identified in paragraph (j) of this AD. Information may be emailed
to: <a href="/cdn-cgi/l/email-protection#61202c2e22210700004f060e17"><span class="__cf_email__" data-cfemail="afeee2e0ecefc9cece81c8c0d9">[email protected]</span></a>.
(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) Additional Information
For more information about this AD, contact Molly Sturgis,
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines,
WA 98198; phone: (562) 627-5373; email: <a href="/cdn-cgi/l/email-protection#5b3634373722753a75282f2e293c32281b3d3a3a753c342d"><span class="__cf_email__" data-cfemail="87eae8ebebfea9e6a9f4f3f2f5e0eef4c7e1e6e6a9e0e8f1">[email protected]</span></a>.
(k) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference (IBR) of the material listed in this
paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to the actions
required by this AD, unless the AD specifies otherwise.
(i) Pratt & Whitney (PW) Alert Service Bulletin (ASB) PW4G-112-
A72-365, Revision No. 1, dated June 20, 2024.
(ii) PW ASB PW4G-112-A72-366, dated June 20, 2024.
(iii) PW ASB PW4G-112-A72-367, dated June 20, 2024.
(iv) PW ASB PW4G-112-A72-368, dated June 20, 2024.
(3) For PW material identified in this AD, contact PW, 400 Main
Street, East Hartford, CT 06118; phone: (800) 565-0140; email:
<a href="/cdn-cgi/l/email-protection#264e434a561412665654475252514e4f5248435f0845494b"><span class="__cf_email__" data-cfemail="c2aaa7aeb2f0f682b2b0a3b6b6b5aaabb6aca7bbeca1adaf">[email protected]</span></a>; website: <a href="http://connect.prattwhitney.com">connect.prattwhitney.com</a>.
(4) You may view this material 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.
(5) You may view this material at the National Archives and
Records Administration (NARA). For information on the availability
of this material at NARA, visit <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#8ceafea2e5e2fffce9eff8e5e3e2cce2edfeeda2ebe3fa"><span class="__cf_email__" data-cfemail="eb8d99c58285989b8e889f828485ab858a998ac58c849d">[email protected]</span></a>.
Issued on June 3, 2025.
Lona C. Saccomando,
Acting Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2025-10332 Filed 6-5-25; 8:45 am]
BILLING CODE 4910-13-P
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