Airworthiness Directives; Pratt & Whitney Canada Corp. Engines

[Federal Register Volume 90, Number 52 (Wednesday, March 19, 2025)]
[Rules and Regulations]
[Pages 12679-12682]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-04441]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2539; Project Identifier MCAI-2023-00971-E; 
Amendment 39-22985; AD 2025-05-13]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney Canada Corp. 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 Pratt & Whitney Canada Corp. (P&WC) Model PW535E and PW535E1 
engines. This AD was prompted by a manufacturer design review that 
indicated certain flange bolts securing the gas generator case and 
turbine support case are susceptible to cracking at their current low-
cycle fatigue (LCF) life. This AD requires repetitive borescope 
inspections (BSI) of the gas generator case to turbine support case 
retaining bolts for evidence of bolt cracks, bolt fracture, missing 
bolts, or loose bolts and replacement, if necessary, as specified in a 
Transport Canada AD, which is incorporated by reference. The FAA is 
issuing this AD to address the unsafe condition on these products.

[[Page 12680]]


DATES: This AD is effective April 23, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of April 23, 
2025.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No.FAA-2024-2539; 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, the mandatory continuing airworthiness 
information (MCAI), 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 Transport Canada material identified in this AD, 
contact Transport Canada, Transport Canada National Aircraft 
Certification, 159 Cleopatra Drive, Nepean, Ontario, K1A 0N5, Canada; 
phone: (888) 663-3639; email: [email protected]; website: tc.canada.ca/en/aviation.
    <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 
regulations.gov under Docket No. FAA-2024-2539.

FOR FURTHER INFORMATION CONTACT: Barbara Caufield, Aviation Safety 
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 
(781) 238-7146; 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 P&WC Model 
PW535E and PW535E1 engines. The NPRM published in the Federal Register 
on November 26, 2024 (89 FR 93225). The NPRM was prompted by Transport 
Canada AD CF-2023-60, dated August 14, 2023 (Transport Canada AD CF-
2023-60) (also referred to as the MCAI), issued by Transport Canada, 
which is the aviation authority for Canada. The MCAI states that data 
from a design review by the manufacturer identified insufficient LCF 
life for flange bolts, having part number (P/N) MS9696-08 and P/N 
MS9489-06, that secure the engine gas generator and turbine support 
cases. At certain high-stress circumferential locations, LCF cracks 
could develop on the flange bolt and lead to fracture of the bolt. 
Multiple fractured bolts could lead to flange separation or case 
rupture, which may damage the engine and the airplane. To address this 
unsafe condition, the manufacturer published material that provides 
instructions for repetitive BSIs and replacement of the affected parts.
    In the NPRM, the FAA proposed to require repetitive BSI of the gas 
generator case to turbine support case retaining bolts for evidence of 
bolt cracks, bolt fracture, missing bolts, or loose bolts, and 
replacement, if necessary. The FAA is issuing this AD to address the 
unsafe condition on these products.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2024-2539.

Discussion of Final Airworthiness Directive

Comments

    The FAA received no comments on the NPRM or on the determination of 
the costs.

Conclusion

    These products have been approved by the aviation authority of 
another country and are approved for operation in the United States. 
Pursuant to the FAA's bilateral agreement with this State of Design 
Authority, it has notified the FAA of the unsafe condition described in 
the MCAI referenced above. The FAA reviewed the relevant data 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.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed Transport Canada AD CF-2023-60, which identifies 
the affected gas generator case to turbine support case retaining bolts 
and specifies procedures for repetitive BSIs and replacement.
    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.

Differences Between This AD and the MCAI

    Where the service information referenced in Transport Canada AD CF-
2023-60 requires reporting certain information to the manufacturer, 
this AD does not require such a submission.

Costs of Compliance

    The FAA estimates that this AD affects 521 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
----------------------------------------------------------------------------------------------------------------
BSI of gas generator case to turbine    2 work-hours x $85 per                $0            $170         $88,570
 support case retaining bolts.           hour = $170.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary 
replacements that are required based on the results of the inspection. 
The agency has no way of determining the number of engines that might 
need these replacements:

[[Page 12681]]



                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replacement of the gas generator case to        4 work-hours x $85 per hour =           $337,701        $338,041
 turbine support case retaining bolts.           $340.
----------------------------------------------------------------------------------------------------------------

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(f), 40113, 44701.


Sec.  39.13  [Amended]

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

2025-05-13 Pratt & Whitney Canada Corp.: Amendment 39-22985; Docket 
No. FAA-2024-2539; Project Identifier MCAI-2023-00971-E.

(a) Effective Date

    This airworthiness directive (AD) is effective April 23, 2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Pratt & Whitney Canada Corp. (P&WC) Model 
PW535E and PW535E1 engines, as identified in Transport Canada Civil 
Aviation AD CF-2023-60, dated August 14, 2023 (Transport Canada AD 
CF-2023-60).

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by a manufacturer design review that 
indicated certain flange bolts securing the gas generator case and 
turbine support case have an inadequate low-cycle fatigue life. The 
FAA is issuing this AD to prevent crack, fracture, missing, or 
loosening of the gas generator case to turbine support case 
retaining bolts. The unsafe condition, if not addressed, could 
result in uncontained engine debris, 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

    Except as specified in paragraphs (h) and (i) of this AD: 
Perform all required actions within the compliance times specified 
in, and in accordance with, Transport Canada AD CF-2023-60.

(h) Exceptions to Transport Canada AD CF-2023-60

    (1) Where Transport Canada AD CF-2023-60 requires compliance 
from its effective date, this AD requires using the effective date 
of this AD.
    (2) Where paragraph A.1. of Transport Canada AD CF-2023-60 
refers to ``discrepancy,'' this AD defines that as ``evidence of 
bolt cracks, bolt fracture, missing bolts, or loose bolts.''
    (3) Where paragraph A.2. in Transport Canada AD CF-2023-60 
specifies to ``Repeat the above paragraph A.1. inspection and 
rectification requirements of this AD at intervals not to exceed 400 
engine cycles,'' this AD requires replacing that text with ``Repeat 
the above paragraph A.1. inspection and rectification requirements 
of this AD thereafter at intervals not to exceed 400 engine 
cycles.''
    (4) Where paragraph A.1. in Transport Canada AD CF-2023-60 
specifies to ``Inspect the bolts P/N MS9696-08 and P/N MS9489-06 
within 400 cycles from the effective date of this AD,'' this AD 
requires replacing that text with ``Inspect affected bolts having P/
N MS9696-08 and P/N MS9489-06 within 400 engine cycles from the 
effective date of this AD.''
    (5) Where paragraph A.1. in Transport Canada AD CF-2023-60 
specifies to ``rectify any discrepancy in accordance with the 
Accomplishment Instructions of the applicable SB,'' this AD requires 
replacing that text with ``Following inspection, if any bolts are 
determined to be in an unserviceable condition, before further 
flight, replace the affected bolts in accordance with the applicable 
SB.''

(i) No Reporting Requirement

    Although the service information referenced in Transport Canada 
AD CF-2023-60 specifies to submit certain information to the 
manufacturer, this AD does not include that requirement.

(j) Alternative Methods of Compliance (AMOCs)

    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 and email to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(k) Additional Information

    For more information about this AD, contact Barbara Caufield, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des

[[Page 12682]]

Moines, WA 98198; phone: (781) 238-7146; email: 
[email protected].

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference 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 do the actions 
required by this AD, unless the AD specifies otherwise.
    (i) Transport Canada AD CF-2023-60, dated August 14, 2023.
    (ii) [Reserved]
    (3) For Transport Canada material identified in this AD, contact 
Transport Canada, Transport Canada National Aircraft Certification, 
159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; phone: (888) 
663-3639; email: [email protected]; website: tc.canada.ca/en/
aviation.
    (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 www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].

    Issued on March 6, 2025.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2025-04441 Filed 3-18-25; 8:45 am]
BILLING CODE 4910-13-P

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