DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2023-0022; Project Identifier MCAI-2022-00564-E]
Airworthiness Directives; Pratt & Whitney Canada Corporation
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for certain Pratt & Whitney Canada Corporation (P&WC) PW308A and PW308C
model turbofan engines. This proposed AD was prompted by a
manufacturer's design review which identified that the combustion
chamber outer case (CCOC) to rear compressor case (RCC) flange bolt low
cycle fatigue life was inadequate and that those flange bolts may
develop cracks resulting in flange bolt fracture. This proposed AD
would require replacing all CCOC flange bolts and modifying the CCOC
and inner bypass ducts. This proposed AD would also prohibit
installation of certain flange bolts on any affected engine, as
specified in a Transport Canada AD, which is proposed for incorporation
by reference (IBR). The FAA is proposing this AD to address the unsafe
condition on these products.
DATES: The FAA must receive comments on this NPRM by March 10,
ADDRESSES: You may send comments, using the procedures found in
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-2023-0022; 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
Material Incorporated by Reference:
For material that is proposed for IBR in this AD, contact Transport
Canada, Transport Canada National Aircraft Certification, 159 Cleopatra
Drive, Nepean, Ontario K1A 0N5, Canada; phone: (888) 663-3639; email:
AD-CN@tc.gc.ca. You may find this material on the Transport Canada
website at tc.canada.ca/en/aviation.
You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 1200
District Avenue, Burlington, MA 01803. For information on the
availability of this material at the FAA, call (817) 222-5110.
FOR FURTHER INFORMATION CONTACT: Barbara Caufield, Aviation Safety
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: (781) 238-7146; email: email@example.com.
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-2023-0022; Project Identifier
MCAI-2022-00564-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, ECO Branch, FAA, 1200
District Avenue, Burlington, MA 01803; phone: (781) 238-7146; email:
firstname.lastname@example.org. Any commentary that the FAA receives which is
not specifically designated as CBI will be placed in the public docket
for this rulemaking.
Transport Canada, which is the aviation authority for Canada, has
issued Transport Canada AD CF-2022-22, dated April 22, 2022 (referred
to after this as ``the MCAI''), to correct an unsafe condition on P&WC
PW308A model turbofan engines with build specification (BS) BS935 and
BS1249, serial numbers PCE-CE0180 and prior, and PW308C model turbofan
engines with BS1047 and BS1238, serial numbers PCE-CF0967 and prior.
The MCAI states that during a design review, the manufacturer
identified that the existing low cycle fatigue life of the flange bolts
that secure the CCOC and the RCC is inadequate. As of May 6, 2022 (the
effective date of Transport Canada AD CF-2022-22), there have been no
reports of cracked flange bolts, however the MCAI states there is
potential that cracks could develop on the flange bolt which could lead
to fracture of the bolt. The MCAI also states that to address the
potential cracking issue, P&WC introduced redesigned flange bolts made
of an improved fatigue resistant material. P&WC also introduced revised
procedures to modify the CCOC and the inner bypass duct flange with
chamfers to reverse the installation direction of the flange bolts. The
MCAI specifies installation of the redesigned bolt configuration,
modifications to the COCC and inner bypass duct, and specifies an
installation prohibition for flange bolts with part numbers MS9698-08
or MS9698-09 on the affected engines. The FAA is proposing this AD to
prevent cracking and fracture of the flange bolts which may result in
flange separation or case rupture, damage to the engine and damage to
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2023-0022.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Transport Canada AD CF-2022-22, which specifies
instructions for replacing certain CCOC flange bolts and modifying the
CCOC and inner bypass ducts. Transport Canada AD CF-2022-22 also
specifies an installation prohibition for flange bolts with part
numbers MS9698-08 and MS9698-09 on the affected engines.
This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in ADDRESSES.
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 described 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 these same type designs.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions specified
in Transport Canada AD CF-2022-22, 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.''
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 since
coordinated with other manufacturers and CAAs to use this process. As
result, the FAA proposes to incorporate by reference Transport Canada
AD CF-2022-22 in the FAA final rule. This proposed AD would, therefore,
require compliance with Transport Canada AD CF-2022-22 in its entirety
through that incorporation, except for any differences identified as
exceptions in the regulatory text of this proposed AD. Using common
terms that are the same as the heading of a particular section in the
Transport Canada AD does not mean that operators need comply only with
that section. For example, where the AD requirement refers to
``Compliance,'' compliance with this AD requirement is not limited to
the section titled ``Corrective Actions'' in Transport Canada AD CF-
2022-22. Service information required by the Transport Canada AD for
compliance will be available at regulations.gov by searching for and
locating Docket No. FAA-2023-0022 after the FAA final rule is
Differences Between This Proposed AD and the MCAI
Where the service information referenced in Transport Canada AD CF-
2022-22 requires reporting certain information to the manufacturer,
this proposed AD would not require reporting the information to the
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 668 engines installed on airplanes of U.S. Registry.
The FAA estimates the following costs to comply with this proposed
|Remove and replace all CCOC flange
||1.5 work-hours x $85 per hour
|Modify the CCOC and inner bypass
||1.5 work-hours x $85 per hour
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.
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
(1) Is not a ``significant regulatory action'' under Executive
(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
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