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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]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney Canada Corp. 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 Canada Corp. (P&WC) Model PW535E and
PW535E1 engines. This proposed 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 proposed AD would require
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 proposing this AD to address the unsafe condition
on these products.
DATES: The FAA must receive comments on this NPRM by January 10, 2025.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to regulations.gov. Follow
the instructions for submitting comments.
Fax: (202) 493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
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 NPRM, the mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
street address for Docket Operations is listed above.
Material Incorporated by Reference:
For Transport Canada material identified in this proposed
AD, contact Transport Canada, Transport Canada National Aircraft
Certification, 159 Cleopatra Drive, Nepean, Ontario, K1A 0N5, Canada;
phone: (888) 663-3639; email: TC.AirworthinessDirectives-Consignesdenavigabilite.TC
@tc.gc.ca; website: tc.canada.ca/en/aviation.
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: Barbara Caufield, Aviation Safety
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone:
(781) 238-7146; email: barbara.caufield@faa.gov.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include "Docket No. FAA-2024-2539; Project Identifier
MCAI-2023-00971-E" at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
this proposal because of those comments.
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received about this NPRM.
Confidential Business Information
CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this NPRM contain commercial
or financial information that is customarily treated as private, that
you actually treat as private, and that is relevant or responsive to
this NPRM, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as "PROPIN." The FAA will treat such marked submissions as
confidential under the FOIA, and they will not be placed in the public
docket of this NPRM. Submissions containing CBI should be sent to
Barbara Caufield, 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
Transport Canada, which is the aviation authority for Canada, has
issued Transport Canada AD CF-2023-60, dated August 14, 2023 (Transport
Canada AD CF-2023-60) (also referred to as the MCAI), to correct an
unsafe condition for certain P&WC Model PW535E and PW535E1 engines. The
MCAI states that data from a design review by the manufacturer
identified insufficient LCF life for flange bolts securing the engine
gas generator and turbine support case. At certain high-stress
circumferential locations, LCF cracks could develop on the flange bolt
and lead to fracture of the bolt. To address this potential unsafe
condition, the manufacturer published material that provides
instructions for repetitive BSIs and replacement of the affected parts.
The FAA is proposing this AD to prevent fracture 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.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2024-2539.
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.
FAA's Determination
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 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.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions specified
in Transport Canada AD CF-2023-60 described previously, except for any
differences identified as exceptions in the regulatory text of this
proposed AD and except as discussed under "Differences Between this
Proposed AD and the MCAI."
Differences Between This Proposed AD and the MCAI
Where the service information referenced in Transport Canada AD CF-
2023-60 requires reporting certain information to the manufacturer,
this proposed AD would not require such a submission.
Explanation of Required Compliance Information
In the FAA's ongoing efforts to improve the efficiency of the AD
process, the FAA developed a process to use some civil aviation
authority (CAA) ADs as the primary source of information for compliance
with requirements for corresponding FAA ADs. The FAA has been
coordinating this process with manufacturers and CAAs. As a result, the
FAA proposes to incorporate Transport Canada AD CF-2023-60 by reference
in the FAA final rule. This proposed AD would, therefore, require
compliance with Transport Canada AD CF-2023-60 in its entirety through
that incorporation, except for any differences identified as exceptions
in the regulatory text of this proposed AD. Material required by
Transport Canada AD CF-2023-60 for compliance will be available at
regulations.gov under Docket No. FAA-2024-2539 after the FAA final rule
is published.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 1,042 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
Estimated Costs
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ACTION
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LABOR COST
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PARTS COST
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COST PER PRODUCT
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COST ON U.S. OPERATORS
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BSI of gas generator case to turbine support case retaining bolts.
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2 work-hours x $85 per hour = $170.
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$0
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$170
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$177,140
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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
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LABOR COST
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PARTS COST
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COST PER PRODUCT
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Replacement of the gas generator case to turbine support case retaining bolts.
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4 work-hours x $85 per hour = $340.
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$4,500
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$4,840
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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
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]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
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