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[Federal Register Volume 80, Number 84 (Friday, May 1, 2015)]
[Rules and Regulations]
[Pages 24791-24793]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-10075]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2013-0766; Directorate Identifier 2013-NE-26-AD; 
Amendment 39-18149; AD 2014-17-08R1]
RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney Canada Corp. Turboprop 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are revising airworthiness directive (AD) 2014-17-08 for 
all Pratt & Whitney Canada Corp. (P&WC) PT6A-114 and PT6A-114A 
turboprop engines. AD 2014-17-08 required initial and repetitive 
borescope inspections (BSIs) of compressor turbine (CT) blades, and the 
removal from service of blades that fail inspection. This new AD adds 
an additional single crystal CT blade, reduces the affected population, 
and corrects the Credit for Previous Action paragraph. This AD was 
prompted by P&WC development of an additional single crystal CT blade 
that corrects the unsafe condition. We are issuing this AD to prevent 
failure of CT blades, which could result in damage to the engine and 
damage to the airplane.

DATES: This AD is effective June 5, 2015.
    The Director of the Federal Register approved the incorporation by 
reference of a certain other publications listed in this AD as of 
October 8, 2014 (79 FR 52172, September 3, 2014).

ADDRESSES: For service information identified in this AD, contact Pratt 
& Whitney Canada Corp., 1000 Marie-Victorin, Longueuil, Quebec, Canada, 
J4G 1A1; phone: 800-268-8000; fax: 450-647-2888; Internet: www.pwc.ca. 
You may view this service information at the FAA, Engine & Propeller 
Directorate, 12 New England Executive Park, Burlington, MA. For 
information on the availability of this material at the FAA, call 781-
238-7125. Certain service information is also available on the Internet 
at http://www.regulations.gov by searching for and locating Docket No. 
FAA-2013-0766.

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-2013-
0766; or in person at the Docket Management Facility between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The AD docket 
contains this AD, the regulatory evaluation, any comments received, and 
other information. The address for the Docket Office (phone: 800-647-
5527) is Document Management Facility, U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Barbara Caufield, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; phone: 781-238-7146; 
fax: 781-238-7199; email: barbara.caufield@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to revise AD 2014-17-08, Amendment 39-17961 (79 FR 52172, 
September 3, 2014), (``AD 2014-17-08''). AD 2014-17-08 applied to all 
P&WC PT6A-114 and PT6A-114A turboprop engines. The NPRM published in 
the Federal Register on December 1, 2014 (79 FR 71031). The NPRM was 
prompted by P&WC development of an additional single crystal CT blade 
that corrects the unsafe condition. The addition of this new part 
number (P/N) reduces the affected population. The NPRM proposed to 
retain all the requirements of AD 2014-17-08. The NPRM also proposed to 
add

[[Page 24792]]

the additional single crystal CT blade that corrects the unsafe 
condition, reduce the affected population, and correct the Credit for 
Previous Action paragraph. We are issuing this AD to prevent failure of 
CT blades, which could result in damage to the engine and damage to the 
airplane.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the NPRM (79 
FR 71031, December 1, 2014) and the FAA's response to each comment.

Request To Clarify Disposition of Removed CT Blades

    Hawkins Aero Engineering, Inc. and another commenter requested that 
we state more clearly whether pre-SB (service bulletin) PT6A-72-1669 CT 
blades removed as a result of this AD can be reinstalled in the same 
engine, the same model engine, or a different model engine.
    We disagree. Paragraph (e)(1)(iii)(B) of this AD clearly states 
that to re-install removed pre-SB PT6A-72-1669 CT blades, the blades 
must pass a two-blade metallurgical inspection to determine 
airworthiness in accordance with paragraph 3.B., Accomplishment 
Instructions, of P&WC Service Bulletin (SB) No. PT6A-72-1669, Revision 
9, dated June 28, 2013. We did not change this AD.

Request To Not Mandate Installation of Single Crystal CT Blades

    One commenter requested that we not mandate the installation of 
single crystal CT blades because two of the P/Ns cited as replacement 
blades have experienced low-time failures, indicating a design or 
manufacturing flaw.
    We disagree. While there have been some failures of single crystal 
CT blades on a different engine model, that failure mode is well 
understood and does not affect the engines that are the subject of this 
AD. For the engines that are subject to this AD, single crystal blades 
provide a significant improvement in durability and a significant 
reduction in CT blade failures overall. We did not change this AD.

Request To Reference Two Additional SBs

    One commenter requested that we reference P&WC SBs No. PT6A-72-1727 
and No. PT6A-72-1749 in addition to P&WC SB No. PT6A-72-1669 because 
each one of these SBs references one of the three single crystal CT 
blades that can be installed as terminating action to this AD. P&WC SB 
No. PT6A-72-1669 alone only references one of the three blades listed 
as terminating action in paragraph (e)(2) of this AD.
    We agree. We added references to the two additional SBs in 
paragraph (h)(2) of this AD.

Request To Include Alternative Method of Compliance (AMOC) for 
Inspections

    Hawkins Aero Engineering, Inc. requested that we include in the AD 
an AMOC to allow a visual inspection, accomplished by splitting the 
engine at the C-flange, as an alternative method to the required 
periodic borescope inspection of pre-SB PT6A-72-1669 CT blades. The 
commenter states that this suggested visual method would provide easier 
detection of cracks.
    We disagree. This AD contains the required method for resolving the 
unsafe condition. If an operator can accomplish required actions in a 
better way, or a way that better suits the operator's business 
processes, and the alternative method provides an acceptable level of 
safety, then the operator can apply for an AMOC to use that method to 
address the unsafe condition in accordance with paragraph (g)(2) of 
this AD. We did not change this AD.

Request That We Address Failures in Additional Blades

    Hawkins Aero Engineering, Inc. requested that we address single 
crystal CT blade failures either in this or in another AD because there 
have been several low-time single crystal CT blade failures in several 
different PT6 engine models, some of which are single engine 
installations.
    We disagree. Low-time failures that occurred on engine models not 
affected by this AD are due to a failure mode that is well understood. 
That failure mode does not occur in the engine models that are the 
subject of this AD. We did not change this AD.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this AD with the changes described previously. We have determined that 
these minor changes:
     Are consistent with the intent that was proposed in the 
NPRM (79 FR 71031, December 1, 2014) for correcting the unsafe 
condition; and
     Do not add any additional burden upon the public than was 
already proposed in NPRM (79 FR 71031, December 1, 2014).
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this AD.

Costs of Compliance

    We estimate that this AD affects 300 engines installed on airplanes 
of U.S. registry. We also estimate that it would take about 4 hours per 
engine to perform the required inspection and 8 hours to replace the 
blades. The average labor rate is $85 per hour. Required parts cost 
about $59,334 per engine. Based on these figures, we estimate the cost 
of this AD on U.S. operators to be $18,106,200.

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.
    We are 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

    We have determined that 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) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska to the extent 
that it justifies making a regulatory distinction, and
    (4) 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.

[[Page 24793]]

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of 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(g), 40113, 44701.

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by removing Airworthiness Directive (AD) 
2014-17-08, Amendment 39-17961 (79 FR 52172, September 3, 2014), and 
adding the following new AD:

2014-17-08R1 Pratt & Whitney Canada Corp.: Amendment 39-18149; 
Docket No. FAA-2013-0766; Directorate Identifier 2013-NE-26-AD.

(a) Effective Date

    This AD is effective June 5, 2015.

(b) Affected ADs

    This AD replaces AD 2014-17-08, Amendment 39-17961 (79 FR 52172, 
September 3, 2014).

(c) Applicability

    This AD applies to all Pratt & Whitney Canada Corp. (P&WC) PT6A-
114 and PT6A-114A turboprop engines.

(d) Unsafe Condition

    This AD was prompted by several incidents of compressor turbine 
(CT) blade failure, causing power loss, and engine failure. We are 
issuing this AD to prevent failure of CT blades, which could lead to 
damage to the engine and damage to the airplane.

(e) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.
    (1) For engines installed with CT blades other than P&WC single 
crystal CT blades, part numbers (P/Ns) 3072791-01, 3072791-02, or 
3079351-01, do the following:
    (i) Until removed, per the requirements of this AD, borescope 
inspect the CT blade leading and trailing edges, within the 
following intervals, whichever occurs later:
    (A) 150 operating hours after October 8, 2014; or
    (B) 500 operating hours since new; or
    (C) 500 operating hours since last borescope inspection (BSI) of 
the CT blades; or
    (D) Before next flight after the effective date of this AD.
    (ii) Thereafter, repeat the inspection required by paragraph 
(e)(1)(i) of this AD every 500 flight hours time since last 
inspection.
    (iii) At the next hot section inspection (HSI) after the 
effective date of this AD, and each HSI thereafter, replace the 
complete set of CT blades with any of the following:
    (A) New CT blades;
    (B) CT blades that have passed a two-blade metallurgical 
inspection. Use paragraph 3.B., Accomplishment Instructions, of P&WC 
Service Bulletin (SB) No. PT6A-72-1669, Revision 9, dated June 28, 
2013, to do the inspection; or
    (C) P&WC single crystal CT blades, P/N 3072791-01, 3072791-02, 
or 3079351-01.
    (2) Replacement of the complete set of CT blades with single 
crystal CT blades, P/N 3072791-01, 3072791-02, or 3079351-01 is 
terminating action for the requirements of paragraph (e)(1) of this 
AD.
    (3) By October 8, 2017, replace the complete set of CT blades 
with P&WC single crystal CT blades, P/N 3072791-01, 3072791-02, or 
3079351-01.

(f) Credit for Previous Action

    Performance of the metallurgical examination specified in 
paragraph (e)(1)(iii)(B) of this AD on CT blades other than P&WC 
single crystal CT blades, P/N 3072791-01, 3072791-02, or 3079351-01, 
before the effective date of this AD fulfills the initial inspection 
requirements of paragraph (e)(1)(i) of this AD. However, you must 
still comply with the repetitive BSI requirement of paragraph 
(e)(1)(ii) of this AD until you complete the mandatory terminating 
action of paragraph (e)(3) of this AD.

(g) Alternative Methods of Compliance (AMOCs)

    (1) AMOCs previously approved for AD 2014-17-08, Amendment 39-
17961 (79 FR 52172, September 3, 2014) are approved for this AD.
    (2) The Manager, Engine Certification Office, FAA, may approve 
AMOCs for this AD. Use the procedures found in 14 CFR 39.19 to make 
your request. You may email your request to: ANE-AD-AMOC@faa.gov.

(h) Related Information

    (1) For more information about this AD, contact Barbara 
Caufield, Aerospace Engineer, Engine Certification Office, FAA, 
Engine & Propeller Directorate, 12 New England Executive Park, 
Burlington, MA 01803; phone: 781-238-7146; fax: 781-238-7199; email: 
barbara.caufield@faa.gov.
    (2) P&WC SB No. PT6A-72-1727, dated August 23, 2013, and SB No. 
PT6A-72-1749, dated September 23, 2014, which are not incorporated 
by reference in this AD, can be obtained from P&WC using the contact 
information in paragraph (i)(4) of this AD.

(i) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (3) The following service information was approved for IBR on 
October 8, 2014 (79 FR 52172, September 3, 2014).
    (i) Pratt & Whitney Canada Service Bulletin No. PT6A-72-1669, 
Revision 9, dated June 28, 2013.
    (ii) Reserved.
    (4) For P&WC service information identified in this AD, contact 
Pratt & Whitney Canada Corp., 1000 Marie-Victorin, Longueuil, 
Quebec, Canada, J4G 1A1; phone: 800-268-8000; fax: 450-647-2888; 
Internet: www.pwc.ca.
    (5) You may view this service information at FAA, Engine & 
Propeller Directorate, 12 New England Executive Park, Burlington, 
MA. For information on the availability of this material at the FAA, 
call 781-238-7125.
    (6) You may view this service information at the National 
Archives and Records Administration (NARA). For information on the 
availability of this material at NARA, call 202-741-6030, or go to: 
http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Burlington, Massachusetts, on April 17, 2015.
Thomas A. Boudreau,
Acting Directorate Manager, Engine & Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2015-10075 Filed 4-30-15; 8:45 am]
 BILLING CODE 4910-13-P
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