[Federal Register Volume 85, Number 159 (Monday, August 17, 2020)]
[Proposed Rules]
[Pages 49981-49983]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-17783]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0692; Project Identifier MCAI-2019-00140-E]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney Canada Corp. Turboprop 
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 all Pratt & Whitney Canada Corp. PT6A-34, -34B, -34AG, -114, and -
114A model turboprop engines. This proposed AD was prompted by several 
reports of low-time fractures of compressor turbine (CT) blades 
resulting in loss of power or in-flight shutdown of the engine. This 
proposed AD would require replacement of certain CT vanes. This 
proposed AD would also require removal from service of certain CT 
blades when these blades have been operated with certain CT vanes. 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 October 1, 
2020.

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 https://www.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.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-
0692; 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. Comments will be available in the AD 
docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Barbara Caufield, Aerospace Engineer, 
ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: 
781-238-7146; fax: 781-238-7199; email: [email protected].

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-2020-0692; 
Project Identifier MCAI-2019-00140-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 NPRM 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 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact we received about this proposal.

Confidential Business Information

    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, Aerospace Engineer, ECO Branch, 
FAA, 1200 District Avenue, Burlington, MA 01803. Any commentary that 
the FAA receives which is not specifically designated as CBI will be 
placed in the public docket for this rulemaking.

[[Page 49982]]

Background

    Transport Canada, which is the aviation authority for Canada, has 
issued Canada AD CF 2019-30R1, dated December 17, 2019 (referred to 
after this as ``the MCAI''), to address the unsafe condition on these 
products. The MCAI states:

    There have been several reported events of low time CT blade 
fractures resulting in power loss/In-flight shutdown (IFSD) on post 
P&WC Service Bulletin (SB) 1669 configured PT6A-114 engines, 
featuring new CMSX-6 CT blades. In addition, relatively low time 
failures of Non-P&WC CT blades have also been reported on PT6A-34 
and -114 series engines.
    In service data shows that these low time failures were reported 
on engines that had CT vanes installed that were repaired in 
accordance with repair specification number STI 72-50-254 held by 
Southwest Turbine Inc. (STI). Most of the affected engines are 
installed on single-engine powered aeroplanes and some events have 
resulted in the loss of the aeroplane and fatalities.
    Dimensional checks and operational testing of the subject STI 
repaired CT vane removed from an incident engine, revealed that it 
did not conform to the engine manufacturer's CT vane type design 
criteria. The noted variations and features in the STI repaired CT 
vane can cause airflow distortion and subsequent aerofoil excitation 
of the CT blades resulting in High Cycle Fatigue (HCF) failure of 
the CT blades. Test data indicates that the stress levels induced in 
CT blades by the adverse effect of subject airflow distortion 
exceeds the design requirements for CMSX-6 CT blades.
    An IFSD or loss of power on a single-engine powered aeroplane 
under certain conditions can lead to an unsafe condition as seen in 
some past events. AD CF-2019-30 was issued on 19 August 2019 to 
address the potential hazard of power loss/IFSD as a result of CT 
blade failures on engines with CT vanes installed that were repaired 
in accordance with repair specification number STI 72-50-254.
    This AD revision, CF-2019-30R1, is issued to update the 
background information and to clarify the affected P&WC CT blade 
Part Numbers (P/Ns).

    You may obtain further information by examining the MCAI in the AD 
docket on the internet at https://www.regulations.gov by searching for 
and locating Docket No. FAA-2020-0692.

FAA's Determination

    This product has been approved by the aviation authority of Canada 
and is approved for operation in the United States. Pursuant to our 
bilateral agreement with Canada, they have notified us of the unsafe 
condition described in the MCAI and service information referenced 
above. The FAA is issuing this NPRM because we evaluated all the 
relevant information provided by Transport Canada and determined the 
unsafe condition described previously is likely to exist or develop in 
other products of the same type design.

Proposed AD Requirements

    This proposed AD would require replacement of certain CT vanes. 
This proposed AD would also require removal from service of certain CT 
blades when these blades have been operated with certain CT vanes.

Costs of Compliance

    The FAA estimates that this proposed AD affects 907 engines 
installed on airplanes of U.S. registry. The FAA estimates that 63 
engines will need to replace the CT vanes and CT blades.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Remove and replace certain CT vanes...  16 work-hours x $85 per         $115,789        $117,149      $7,380,387
                                         hour = $1,360.
Remove and replace CMSX-6 CT blade set  16 work-hours x $85 per           90,271          91,631       5,772,753
                                         hour = $1,360.
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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) 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 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 (AD):

Pratt & Whitney Canada Corp.: Docket No. FAA-2020-0692; Project 
Identifier MCAI-2019-00140-E.

(a) Comments Due Date

    The FAA must receive comments by October 1, 2020.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all Pratt & Whitney Canada Corp. PT6A-34, -
34B, -34AG, -114, and -114A model turboprop engines.

[[Page 49983]]

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by several reports of low-time fractures of 
compressor turbine (CT) blades resulting in loss of power or in-
flight shutdown of the engine. The FAA is issuing this AD to prevent 
failure of the CT blade. The unsafe condition, if not addressed, 
could result in failure of the engine, in-flight shutdown, and loss 
of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    (1) Within 250 flight hours (FHs) or 270 days after the 
effective date of this AD, whichever occurs first:
    (i) Remove from service any CT vane repaired in accordance with 
Southwest Turbine Inc. (STI) repair specification STI-72-50-254 and 
replace with a non-STI-repaired CT vane.
    (ii) Remove from service any CMSX-6 CT blade that has been 
operated on an affected engine with a CT vane repaired in accordance 
with STI repair specification STI-72-50-254.
    (2) [Reserved]

(h) Installation Prohibition

    After the effective date of this AD, do not install on any 
engine a CT vane that was repaired in accordance with repair 
specification STI-72-50-254.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, ECO 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 
ECO Branch, send it to the attention of the person identified in 
paragraph (j)(1) of this AD. You may email your request 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.

(j) Related Information

    (1) For more information about this AD, contact Barbara 
Caufield, Aerospace Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: 781-238-7146; fax: 781-238-7199; email: 
[email protected].
    (2) Refer to Transport Canada AD CF 2019-30R1, dated December 
17, 2019, for more information. You may examine the Transport Canada 
AD in the AD docket on the internet at https://www.regulations.gov 
by searching for and locating it in Docket No. FAA-2020-0692.

    Issued on August 10, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2020-17783 Filed 8-14-20; 8:45 am]
BILLING CODE 4910-13-P