Rule2026-10360
Airworthiness Directives; Pratt & Whitney RTX Corporation (Type Certificate Previously Held by Pratt & Whitney Division United Technologies Corporation) Engines
Primary source
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Published
May 22, 2026
Effective
June 26, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for certain Pratt & Whitney RTX Corporation (PW) Model PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines. This 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 AD requires 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 issuing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 99 (Friday, May 22, 2026)</title>
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[Federal Register Volume 91, Number 99 (Friday, May 22, 2026)]
[Rules and Regulations]
[Pages 30191-30196]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-10360]
========================================================================
Rules and Regulations
Federal Register
________________________________________________________________________
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having general applicability and legal effect, most of which are keyed
to and codified in the Code of Federal Regulations, which is published
under 50 titles pursuant to 44 U.S.C. 1510.
The Code of Federal Regulations is sold by the Superintendent of Documents.
========================================================================
Federal Register / Vol. 91, No. 99 / Friday, May 22, 2026 / Rules and
Regulations
[[Page 30191]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-0923; Project Identifier AD-2024-00529-E;
Amendment 39-23322; AD 2026-09-02]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney RTX Corporation (Type
Certificate Previously Held by Pratt & Whitney Division United
Technologies Corporation) Engines
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Pratt & Whitney RTX Corporation (PW) Model PW4074, PW4074D,
PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines. This 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 AD requires
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 issuing this AD to address the unsafe condition on
these products.
DATES: This AD is effective June 26, 2026.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of June 26,
2026.
ADDRESSES:
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 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.
Material Incorporated by Reference:
<bullet> 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#acc4c9c0dc9e98ecdcdecdd8d8dbc4c5d8c2c9d582cfc3c1"><span class="__cf_email__" data-cfemail="3c5459504c0e087c4c4e5d48484b545548525945125f5351">[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. It is also available at
<a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2025-0923.
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#2944464545500748075a5d5c5b4e405a694f4848074e465f"><span class="__cf_email__" data-cfemail="177a787b7b6e39763964636265707e645771767639707861">[email protected]</span></a>.
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 PW Model
PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3
engines. The NPRM was published in the Federal Register on June 6, 2025
(90 FR 24085). The NPRM was prompted by an analysis of an event
involving an IAE LLC Model PW1127GA-JM engine, which experienced an HPC
IBR-7 separation that resulted in an aborted takeoff. In the NPRM, the
FAA proposed to 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. The FAA also proposed to require removal from service and
replacement of the HPT 1st-stage air seal for certain serial numbers.
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 six commenters. The commenters were
the Air Line Pilots Association, International (ALPA), All Nippon
Airways (ANA), The Boeing Company (Boeing), PW, United Airlines
(United), and an individual. The following presents the comments
received on the NPRM and the FAA's response to each comment.
Support for the NPRM
ALPA, Boeing, and United expressed support for the NPRM.
Request To Include ``Or Later'' Following Date of Material Citations
ANA requested that the FAA revise the material citations specified
in paragraphs (g)(2)(i) through (iv) of the proposed AD to read ``or
later'' following the revision date. ANA stated that if the material is
revised in the future, an AMOC would be required for implementation.
The FAA disagrees with the request. To incorporate by reference
(IBR) the material specified in this AD, the citation must refer to a
specific document, including the specific revision date. Additionally,
the FAA is unable to cite a future revision to a document which does
not yet exist. If any of the specified material is revised, operators
may request approval of an alternative method of compliance (AMOC) in
accordance with the procedures in paragraph (j) of this AD. The FAA did
not change this AD as a result of this comment.
Request To Clarify Revision Level for Secondary Material
ANA requested that the FAA revise the NPRM to include revision
levels for certain non-destructive inspection procedures (NDIPs) which
are referenced in the material specified in the NPRM, as well as
paragraph (h) of the proposed AD; or refer to the service material
instead. ANA stated that the material specifies instructions for
performing AUSIs based on NDIPs, but the material does not specify a
revision of the non-destructive inspection procedure for those actions.
[[Page 30192]]
Additionally, ANA indicated that maintenance, repair, and overhaul
(MRO) organizations typically list compliance with service bulletins on
the airworthiness release certificates, not compliance with NDIPs.
The FAA agrees to clarify. The IBR materials in this AD specify
certain actions using certain NDIPs. All revisions of those specified
NDIPs are acceptable for completing those actions. The FAA has not
changed this AD based on this comment.
Request To Specify Certain Part Numbers in the Required Actions
ANA requested that the FAA include the affected part numbers in the
required actions specified in paragraph (g)(2) of the proposed AD and
throughout the NPRM. ANA stated that the NPRM requires certain actions
for specified part nomenclature but does not include the relevant part
numbers.
The FAA disagrees with the request. The nomenclature of the part is
sufficient to identify the necessary actions. Additionally, the
affected part numbers are specified in the IBR materials which are
required to complete this AD. The FAA has not changed this AD based on
this comment.
Request To Align Part Numbers with the Engine Illustrated Parts Catalog
(EIPC)
ANA requested that the FAA change the part numbers for eligible
parts in the NPRM to align with those provided in the EIPC. ANA stated
that some of the part numbers listed as parts eligible for installation
in the NPRM are not listed in the EIPC, and that ANA is unable to
manage the required action without part numbers based on the EIPC.
The FAA disagrees with the request. The EIPC is intended to depict
part and hardware relationships and accessibility for procurement.
However, the EIPC does not define applicability for inspections or
whether certain parts are eligible for installation. The part numbers
specified in this AD are based on the manufacturer's service material
and engineering analysis. Additionally, under the provisions of
paragraph (j) of this AD, the FAA will consider requests for approval
of an AMOC if sufficient data are submitted to substantiate an
acceptable level of safety. The FAA has not changed this AD based on
this comment.
Request To Shorten Compliance Times
An individual commenter requested that the FAA shorten the
compliance times specified in the NPRM. The commenter stated that the
current deadlines for compliance are too relaxed and do not match the
urgent need to prevent dangerous failures in key engine parts. The
commenter stated that the recent incident, where an HPC IBR-7
separation that resulted in an aborted takeoff, clearly shows how
immediate this threat is. The commenter requested more immediate
corrective measures with clear deadlines.
The FAA disagrees with the request. The commenter did not provide
specific recommendations for alternative compliance times or
justification for why the proposed compliance times are insufficient.
In developing an appropriate compliance time, the FAA used a data-
driven, quantitative risk analysis which considered the safety
implications, parts availability, and normal maintenance schedules for
timely accomplishment. In consideration of all these factors, the FAA
selected the compliance times to appropriately mitigate the risk
associated with the unsafe condition. This AD permits operators to
accomplish the required actions at a time earlier than the specified
compliance time. If additional data are presented that justify a
shorter compliance time, the FAA may consider further rulemaking on
this issue. The FAA did not change this AD as a result of this comment.
Request for Targeted Metallurgical Testing
An individual commenter requested that the FAA require targeted
metallurgical testing on samples from specific production campaigns
where variability is suspected. The commenter discussed the nature of
nickel powder metallurgy; that minor variations can create microscopic
defects, which may become weaknesses under stress; and that some
production batches are already shown to have resultant anomalies, which
reduce component fatigue life, especially in high-pressure compressors
and turbines. The commenter stated that results from the focused
testing could be used to confirm whether additional parts are at risk
and allow the FAA to adjust inspection intervals accordingly.
The FAA disagrees with the request. The commenter did not provide
any specific recommendations for changes to the actions required by
this AD. The FAA has determined that the manufacturer has improved
their manufacturing and inspection processes and has identified all at-
risk part populations. Additionally, metallurgical testing of this kind
is industry standard as part of the manufacturing quality control
process. The FAA did not change this AD as a result of this comment.
Request To Broaden Scope of Affected Parts
An individual commenter requested that the FAA broaden the criteria
for evaluation or establish a mechanism for rapid re-evaluation of
affected parts in the NPRM. The commenter stated that focusing on
specific serial numbers and part numbers is overly narrow, that the
risk posed by nickel powdered metal inconsistencies is not confined
solely to these items, and that production variability may affect a
larger fraction of similar components. The commenter indicated that
parts from adjacent production campaigns or exhibiting borderline
metallurgical characteristics might equally be at risk. The commenter
stated that broadening the scope of the criteria would ensure
additional hazardous components are identified and managed, which would
reduce the potential for at-risk parts to be overlooked.
The FAA disagrees with the request. The FAA has determined that
there are no adjacent production campaigns and, as stated previously,
the manufacturer has identified all at-risk part populations.
Therefore, this AD applies to the part numbers and serial numbers of
all at-risk components. The FAA did not change this AD as a result of
this comment.
Request for Time-Based Inspection Intervals
An individual commenter requested that the FAA revise the NPRM to
include uniform time-based inspection intervals. The commenter stated
that reliance on ``piece part opportunities'' introduces significant
variability into the safety assurance process. The commenter indicated
that because each operator follows an independent maintenance schedule,
some engines may continue operating with undetected degradation for
extended periods, which could jeopardize the safety of the fleet.
The FAA disagrees with the request. The commenter did not provide
specific recommendations for alternative time-based inspection
intervals or justification for why the proposed compliance times are
insufficient. The FAA acknowledges that piece-part opportunities can be
variable. However, as discussed previously, in developing an
appropriate compliance time, the FAA used a data-driven, quantitative
risk analysis which considered the safety implications, parts
availability, and normal maintenance schedules for timely
accomplishment, which included both the variability and the worst-case
[[Page 30193]]
scenarios. This information was then used to determine that piece part
opportunities appropriately mitigate the risk associated with the
unsafe condition. If additional data are presented that justify a
uniform time-based inspection interval, the FAA may consider further
rulemaking on this issue. The FAA did not change this AD as a result of
this comment.
Request for Mandatory Reporting
An individual requested that the FAA require mandatory reporting in
the NPRM. The commenter stated that data from operators for parts with
abnormal degradation, even without an in-flight failure, would offer
insight into the condition of nickel powdered metal components and
allow the FAA to identify trends early and prevent accidents.
The FAA disagrees with the request. This request falls outside the
scope of this AD, whereas the intent is to detect nickel powder
anomalies, related cracking, and replace the affected parts. The FAA
has a clear understanding of the failure mode, and mandatory reporting
would not increase knowledge of the unsafe condition. Additionally,
these specific nickel powder components do not exhibit abnormal
degradation. Failures or crack indications found during the inspections
required by this AD are already subject to existing mandatory reporting
requirements of the manufacturer. The FAA did not change this AD as a
result of this comment.
Request for Data Sharing and Transparency
An individual commenter requested that the FAA publicly share
aggregated inspection and test results. The commenter stated that the
FAA should be prompt and transparent, and that making this data
publicly available would empower the aviation community to understand
the full scope of the unsafe condition and collaborate in development
of best practices and corrective measures. The commenter referenced
similar transparency measures within the automotive and rail
industries, which improved identification of emerging safety issues and
allowed more effective collaborative solutions. The commenter stated
that this demonstrated clear benefits of open data sharing in enhancing
overall safety.
The FAA disagrees with the request to share data. Much of the
requested aggregated data is proprietary and, consequently, the FAA is
unable to share publicly. As discussed previously, the FAA and the
manufacturer have clear understanding of the failure mode and unsafe
condition. The intent of this AD is to detect nickel powder anomalies
and related cracking and replace the affected parts. The FAA, the
manufacturer, the rest of the industry, and many industry groups have
mechanisms in place to share information and develop industry best
practices. The FAA did not change this AD as a result of this comment.
Request To Mandate Airworthiness Limitations Section (ALS) Updates
Instead of Service Material
PW requested that the FAA revise the NPRM to require updating the
ALS instead of the actions specified in the service material. PW stated
that the inspections specified in the service material for the HPC
15th-stage disks, front turbine hubs, HPT 1st-stage air seals, and HPT
2nd-stage hubs have since been included in the revised engine manual
ALS and are now duplicate requirements.
The FAA partially agrees with the request. The FAA disagrees with
the request to require updating the ALS rather than performing certain
inspections in accordance with the service material; however, the FAA
finds that updating the engine manual ALS provides acceptable
mitigation of the unsafe condition. The FAA has added paragraph (i) of
this AD, which provides optional terminating action for operators that
update their engine manual ALS to include the actions required by
paragraphs (g)(1) through (3) of this AD.
Request To Eliminate the Requirement To Remove From Service
PW requested that the FAA eliminate paragraph (g)(3) of the
proposed AD. PW stated that the requirement to remove the part from
service is sufficiently covered by existing inspection procedures which
are incorporated in the revised engine manual ALS inspections.
The FAA disagrees with the request. This AD does not require any
engine manual ALS updates. Therefore, the FAA finds that including
removal requirements in this airworthiness directive is both
appropriate and necessary. However, as previously discussed, the FAA
has added paragraph (i) of this AD which provides optional terminating
action for operators that update their engine manual ALS to include the
actions required by paragraphs (g)(1) through (3) of this AD. The FAA
did not change this AD as a result of this comment.
Request To Remove Certain Definition of ``Piece Part Opportunity''
PW requested that the FAA remove the definitions specified in
paragraphs (h)(1)(i) through (iii) of the proposed AD. PW stated that
``piece part opportunity'' is already defined in the revised engine
manual ALS inspections.
The FAA disagrees with the request. A definition for ``piece part
opportunity'' is necessary for the required actions in this AD because
the ALS update is an optional terminating action and not mandatory. The
FAA did not change this AD as a result of this comment.
Request To Remove Certain Definition of ``Part Eligible for
Installation''
PW requested that the FAA remove the definitions specified in
paragraph (h)(2) of the proposed AD. PW stated that ``part eligible for
installation'' is already defined in the revised engine manual ALS
inspections. PW proposed that the FAA allow all new manufactured parts
to be eligible for installation regardless of confirmation of receiving
an angle ultrasonic scan inspection (AUSI). PW indicated its fleet
management plan does not require confirmation that new affected parts
have received an AUSI during manufacture to be eligible for
installation. PW stated that including such a requirement places an
unnecessary burden on operators.
The FAA partially agrees with this request. The FAA disagrees with
removing the definition of ``Part Eligible for Installation'' from this
AD. However, the FAA agrees that operators do not have access to the
necessary data to determine whether zero-time components have passed an
AUSI at new part manufacture. Therefore, the FAA has determined that
the responsible party may determine if the part is eligible for
installation based on the date specified on the FAA Form 8130-3. The
FAA has revised paragraphs (h)(2)(xiii) of this AD by removing the
words ``and has passed an AUSI at new part production'' and replacing
them with ``that has an FAA Form 8130-3 from the original equipment
manufacturer for new production dated July 1, 2025, or later.''
Explanation of Change to the Type Certificate Holder's Name
The FAA has revised the applicability of this AD to identify the
type certificate holder's name as published in the most recent type
certificate data sheet for the affected models.
[[Page 30194]]
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, and
any other changes described previously, this AD is adopted as proposed
in the NPRM. None of the changes will increase the economic burden on
any operator.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed the following material:
<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.
Costs of Compliance
The FAA estimates that this AD affects 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 AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
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-hour x $85 per hour 763,000 763,085 4,578,510
(6 engines). = $85.
----------------------------------------------------------------------------------------------------------------
The FAA estimates the following costs to do any replacements that
would be required based on the results of the inspection. The agency
has no way of determining the number of engines that might need these
replacements:
On-Condition Costs
------------------------------------------------------------------------
Cost per
Action Labor cost Parts cost product
------------------------------------------------------------------------
Replace HPC 15th-stage disk.. 10 work-hours x $312,000 $312,850
$85 per hour =
$850.
Replace front turbine hub.... 10 work-hours x 910,000 910,850
$85 per hour =
$850.
Replace HPT 2nd-stage hub.... 10 work-hours x 816,000 816,850
$85 per hour =
$850.
Replace HPT 1st-stage air 10 work-hours x 763,000 763,850
seals. $85 per hour =
$850.
------------------------------------------------------------------------
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.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
2026-09-02 Pratt & Whitney RTX Corporation (Type Certificate
Previously
[[Page 30195]]
Held by Pratt & Whitney Division United Technologies Corporation):
Amendment 39-23322; Docket No. FAA-2025-0923; Project Identifier AD-
2024-00529-E.
(a) Effective Date
This airworthiness directive (AD) is effective June 26, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to certain Pratt & Whitney RTX Corporation (type
certificate previously held by Pratt & Whitney Division United
Technologies Corporation) (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 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
------------------------------------------------------------------------
Serial No. Part No. (P/N)
------------------------------------------------------------------------
CKLBME2702.............................................. 50L663
CKLBME2703.............................................. 50L663
CKLBME2704.............................................. 50L663
CKLBME2705.............................................. 50L663
CKLBME2711.............................................. 50L663
CKLBMS8019.............................................. 50L959
------------------------------------------------------------------------
(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 angle ultrasonic scan inspection (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)-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 that has
an FAA Form 8130-3 from the original equipment manufacturer for new
production dated July 1, 2025, or later.
(i) Optional Terminating Action--Airworthiness Limitations Section
(ALS) Revision
Revising the ALS of the existing engine manual and the
operator's existing approved maintenance program or inspection
program, as applicable, by incorporating the information in figure 1
to paragraph (i) of this AD, constitutes terminating action for the
actions required by paragraphs (g)(1) through (3) of this AD.
[[Page 30196]]
Figure 1 to Paragraph (i)--ALS Additional Inspections
----------------------------------------------------------------------------------------------------------------
B. Parts requiring CIR manual 51A750 inspection check-02 update to
Engine manuals P/N 51A345 and 51A751 inspection description include
----------------------------------------------------------------------------------------------------------------
Chapter/Section 05-10-00 PW4000 SERIES Seal--Air, HPT 1st TASK 72-52-19-200-001.
ENGINE MANUAL ENGINE--AIRWORTHINESS Stage. 1. Non-Destructive Inspection--Stage 1 HPT
LIMITATIONS--TIME LIMITS. Airseal H. Angle Ultrasonic Inspection (1) Do
P/N 51A345 Revision Date: 2025-02-01 an Angle Ultrasonic Inspection for P/N 50L663
TASK 05-10-01-990-004.. by NDIP-1286 and for P/N 50L959 by NDIP-1287.
5. Critical Life Limited Part
Inspection and Critical Part
Inspection..
P/N 51A751 Revision Date: 2025-07-01
TASK 05-10-01-990-007..
5. Critical Life Limited Part
Inspection and Critical Part
Inspection..
Chapter/Section 05-10-00 PW4000 SERIES Hub, Turbine Front TASK 72-52-05-200-001.
ENGINE MANUAL ENGINE--AIRWORTHINESS Assembly (1st Stage). 1. Non-Destructive Inspection--Turbine Front
LIMITATIONS--TIME LIMITS. Hub (Stage 1)-H. Angle Ultrasonic Inspection
P/N 51A345 Revision Date: 2025-02-01 (1) Do an Angle Ultrasonic Inspection for
TASK 05-10-01-990-004.. Assembly P/N 55L221 or Detail P/N 55L801 by
5. Critical Life Limited Part NDIP-1273 and for Assembly P/N 55L521 or
Inspection and Critical Part Detail P/N 55L901 by NDIP-1288.
Inspection..
P/N 51A751 Revision Date: 2025-07-01
TASK 05-10-01-990-007..
5. Critical Life Limited Part
Inspection and Critical Part
Inspection..
Chapter/Section 05-10-00 PW4000 SERIES Hub, Turbine Rear TASK 72-52-06-200-001.
ENGINE MANUAL ENGINE--AIRWORTHINESS Assembly (2nd Stage). 1. Non-Destructive Inspection--Turbine
LIMITATIONS--TIME LIMITS. Intermediate Hub (Stage 2)-H. Angle Ultrasonic
P/N 51A345 Revision Date: 2025-02-01 Inspection (1) Do an Angle Ultrasonic
TASK 05-10-01-990-004.. Inspection for Assembly P/N 53L232 and Detail
5. Critical Life Limited Part P/N 53L202 by NDIP-1274 and for Assembly P/N
Inspection and Critical Part 54L932 and Detail P/N 54L802 by NDIP-1275.
Inspection..
P/N 51A751 Revision Date: 2025-07-01
TASK 05-10-01-990-007..
5. Critical Life Limited Part
Inspection and Critical Part
Inspection..
Chapter/Section 05-10-00 PW4000 SERIES HPC Disk 15th Stage.... TASK 72-35-92-200-001.
ENGINE MANUAL ENGINE--AIRWORTHINESS 1. Non-Destructive Inspection--HPC Disk 15th
LIMITATIONS--TIME LIMITS. Stage-H. Angle Ultrasonic Inspection (1) Do an
P/N 51A345 Revision Date: 2025-02-01 Angle Ultrasonic Inspection for P/N 55H615 and
TASK 05-10-01-990-004.. P/N 51S315 by NDIP-1289.
5. Critical Life Limited Part TASK 72-35-92-200-001-A.
Inspection and Critical Part 1. Non-Destructive Inspection--HPC Disk 15th
Inspection.. Stage-I. Angle Ultrasonic Inspection (1) Do an
P/N 51A751 Revision Date: 2025-07-01 Angle Ultrasonic Inspection for P/N 56H015 and
TASK 05-10-01-990-007.. P/N 51S115 by NDIP-1276.
5. Critical Life Limited Part
Inspection and Critical Part
Inspection..
----------------------------------------------------------------------------------------------------------------
(j) 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 (k) of this AD. Information may be emailed
to: <a href="/cdn-cgi/l/email-protection#d99894969a99bfb8b8f7beb6af"><span class="__cf_email__" data-cfemail="682925272b280e0909460f071e">[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.
(k) 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#402d2f2c2c396e216e33343532272933002621216e272f36"><span class="__cf_email__" data-cfemail="d5b8bab9b9acfbb4fba6a1a0a7b2bca695b3b4b4fbb2baa3">[email protected]</span></a>.
(l) 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 RTX Corporation (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#5038353c206264102022312424273839243e35297e333f3d"><span class="__cf_email__" data-cfemail="1f777a736f2d2b5f6f6d7e6b6b6877766b717a66317c7072">[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#1076623e797e6360757364797f7e507e7162713e777f66"><span class="__cf_email__" data-cfemail="91f7e3bff8ffe2e1f4f2e5f8feffd1fff0e3f0bff6fee7">[email protected]</span></a>.
Issued on May 20, 2026.
Lona C. Saccomando,
Acting Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2026-10360 Filed 5-21-26; 8:45 am]
BILLING CODE 4910-13-P
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This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.