DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0395; Product Identifier 2019-NE-11-AD]
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 certain Pratt & Whitney Canada Corp. (P&WC) PW150A turboprop
engines. This proposed AD was prompted by a determination by the
manufacturer that certain PW150A engine high-pressure (HP) centrifugal
impellers may exhibit a material microstructure anomaly that has a
potential to adversely affect the low cycle fatigue characteristics of
the part. This proposed AD would require replacement of the affected HP
centrifugal impellers. 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 August 8, 2019.

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 http://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.

For service information identified in this NPRM, contact Pratt &
Whitney Canada Corp., 1000 Marie-Victorin, Longueuil, Quebec, Canada,
J4G 1A1; phone: 800-268-8000; fax: 450-647-2888; internet: http://www.pwc.ca.
You may view this service information at the FAA, Engine
and Propeller Standards Branch, 1200 District Avenue, Burlington, MA
01803. For information on the availability of this material at the FAA,
call 781-238-7759.

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.gov
by searching for and locating Docket No. FAA-2019-0395; 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),
the regulatory evaluation, 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: 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 the ADDRESSES section. Include "Docket No. FAA-2019-0395;
Product Identifier 2019-NE-11-AD" at the beginning of your comments.
The FAA specifically invites comments on the overall regulatory,
economic, environmental, and energy aspects of this NPRM. The FAA will
consider all comments received by the closing date and may amend this
NPRM because of those comments.

The FAA will post all comments we receive, without change, to
http://www.regulations.gov, including any personal information you
provide. The FAA will also post a report summarizing each substantive
verbal contact we receive about this NPRM.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued AD CF-2018-12, dated April 27, 2018
(referred to after this as "the MCAI"), to address the unsafe
condition on these products. The MCAI states:

Pratt & Whitney Canada (P&WC) has determined that certain PW150A
engine HP centrifugal impellers, part number (P/N) 3049127-01, may
exhibit a material microstructure anomaly which has a potential to
adversely affect the low cycle fatigue (LCF) characteristics of the
part, resulting in a lower LCF life than currently published in the
engine model's Airworthiness Limitations. The identified discrepancy
was related to specific parts having been exposed to inappropriate
temperature levels during the manufacturing process.

To address the subject potential material microstructure
problem, P&WC issued SB 35331 Initial Issue, dated 16 March 2016,
and then subsequently Revision 1, dated 3 May 2016, to recommend
replacement of specific impeller serial numbers prior to the parts
reaching the determined thresholds. Subsequent to the release of the
SB, P&WC voluntarily initiated a fleet campaign to achieve this
objective.

The actions specified by this AD are to ensure that HP
centrifugal impellers with this potential material anomaly condition
are contained in order to prevent severe engine damage and possible
aeroplane damage caused by an impeller failure.

You may obtain further information by examining the MCAI in the AD
docket on the internet at http://www.regulations.gov by searching for
and locating Docket No. FAA-2019-0395.

Related Service Information Under 1 CFR Part 51

The FAA reviewed P&WC Service Bulletin (SB) PW150-72-35331,
Revision No. 1, dated May 3, 2016. The SB describes procedures for
replacement of the affected HP centrifugal impeller. 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 the ADDRESSES section.

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 in
this proposed AD. The FAA is proposing this AD because we evaluated all
the relevant information provided by Transport Canada Civil Aviation
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 affected HP
centrifugal impellers.

Differences Between This Proposed AD and the MCAI or Service Information

P&WC SB No. PW150-72-35331, Revision No. 1, dated May 3, 2016
("the SB"), indicates HP centrifugal impellers with serial numbers
(S/Ns) listed in Table 1 of the SB should be removed prior to March 31,
2016 (15 days after the issue date of P&WC SB No. 35331, Initial Issue)
and HP centrifugal impellers with S/Ns listed in Table 2 of the SB
should be removed within 150 flight cycles or prior to accumulating
8,000 flight cycles since new. Our proposed AD would require removal of
only the HP centrifugal impellers with S/Ns listed in Table 2 of the SB
since the HP centrifugal impellers with S/Ns listed in Table 1 have
already been removed from service. Our proposed AD is consistent with
the SB and the MCAI in prohibiting the installation of any HP
centrifugal impeller listed in Table 1 or Table 2 of the SB after the
effective date of the proposed AD.

Costs of Compliance

The FAA estimates that this proposed AD affects 20 engines
installed on airplanes of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

Estimated Costs

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.

This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to engines, propellers, and
associated appliances to the Manager, Engine and Propeller Standards
Branch, Policy and Innovation Division.

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, the FAA certifies 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

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 (AD):