AD 2014-17-08

[Federal Register Volume 79, Number 170 (Wednesday, September 3, 2014)]
[Rules and Regulations]
[Pages 52172-52174]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2014-20453]



[[Page 52172]]

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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 39-17961; AD 2014-17-08]
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 adopting a new airworthiness directive (AD) for all 
Pratt & Whitney Canada Corp. (P&WC) PT6A-114 and PT6A-114A turboprop 
engines. This AD requires initial and repetitive borescope inspection 
(BSI) of compressor turbine (CT) blades, and the removal from service 
of blades that fail inspection. This AD was prompted by several 
incidents of CT blade failure, causing power loss, and engine failure. 
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 becomes effective October 8, 2014.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of October 8, 
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.

Examining the AD Docket

    You may examine the AD docket on the Internet at <a href="http://www.regulations.gov">http://www.regulations.gov</a> 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 mandatory continuing airworthiness information 
(MCAI), 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: Robert Morlath, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; phone: 781-238-7154; 
fax: 781-238-7199; email: <a href="/cdn-cgi/l/email-protection#b0c2dfd2d5c2c49ed39edddfc2dcd1c4d8f0d6d1d19ed7dfc6"><span class="__cf_email__" data-cfemail="1d6f727f786f69337e3370726f717c69755d7b7c7c337a726b">[email&#160;protected]</span></a>.

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a supplemental notice of proposed rulemaking (SNPRM) to 
amend 14 CFR part 39 by adding an AD that would apply to the specified 
products. The SNPRM was published in the Federal Register on May 12, 
2014 (79 FR 26901). The SNPRM proposed to correct an unsafe condition 
for the specified products. The MCAI states:

    There have been a number of reported incidents where Compressor 
Turbine (CT) blade failures have caused power loss on PT6A-114 & 
PT6A-114A engines, resulting in in-flight shutdown (IFSD). 
Investigation by engine manufacturer Pratt & Whitney Canada (P&WC) 
has determined that when operated at high power and high temperature 
settings, the subject CT blades are prone to crack/fracture as a 
result of creep and/or sulfidation.
    P&WC issued Service Bulletin (SB) 1669 that introduces a newly 
designed CT blade which has proven to be far less affected by the 
blade ``Creep'' phenomenon. Additionally, to help prevent IFSD by 
identifying pending creep induced blade failure of the pre-SB 1669 
configuration blades, P&WC has revised SB 1669 to include specific 
inspection/maintenance requirements for engines with pre-SB 1669 
configuration CT blade installation.
    An engine power loss or IFSD on a single engine powered 
aeroplane such as Cessna 208 could result in an unsafe condition. AD 
CF-2013-21 was issued on 1 August 2013 to mandate compliance with SB 
1669R9 requirements to inspect and replace the existing CT blades on 
PT6A-114 & PT6A-114A engines with a new type of post SB 1669 
configuration CT blades. P&WC, through SB 1727, has now introduced a 
new version of the post SB 1669 configuration CT blade that features 
a tighter tolerance on the platform width. This enhances the ability 
of the maintainer to achieve the required inter-platform gap.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We considered the comments received.

Request To Remove Mandatory Upgrade

    One commenter requested that we remove the mandatory terminating 
action requirement to install P&WC single crystal CT blades, part 
numbers (P/Ns) 3072791-01 and 3072791-02. The commenter states that 
mandating the installation of an unproven replacement CT blade is not 
prudent and could be costly. The post-SB blade has a questionable 
operating history including failure. This blade has been identified for 
removal in the PT6A-34 and -36 engines, so it should not be made 
mandatory for installation in the PT6A-114 engine.
    We do not agree. P&WC single crystal CT blades, P/Ns 3072791-01 and 
3072791-02, are proven replacement CT blades for the PT6A-114 and PT6A-
114A engines. These single crystal CT blades have successfully 
performed over 2 million flight hours in service and have displayed a 
lower rate of failure than older CT blade designs. An ongoing 
investigation into blade failures on other PT6A series engines has 
shown that the root cause of those failures does not impact the PT6A-
114 and PT6A-114A fleets. Therefore, P&WC single crystal CT blades, P/
Ns 3072791-01 and 3072791-02, have not been identified for removal from 
the PT6A-114 and PT6A-114A series engines. We did not change this AD.

Request To Change Mandatory Terminating Action

    One commenter suggested that the 36-month compliance time for the 
mandatory terminating action is not appropriate. The commenter states 
that mandating replacement of the complete set of single crystal CT 
blades with P/N 3072791-02 blades within 36 months is an undue cost 
burden for certain operators and that the availability of CT blade, P/N 
3072791-02, is unreliable. The operator will not reach the next 
scheduled hot section interval prior to 36 months, thereby causing the 
performance of the next hot section inspection (HSI) sooner than 
necessary.
    We do not agree. The 36-month compliance time for installing single 
crystal CT blades, P/Ns 3072791-01 and 3072791-02, adequately addresses 
the unsafe condition without imposing undue burden on operators. P&WC 
single crystal CT blades, P/Ns 3072791-01 and 3072791-02 are currently 
available from P&WC both as replacement parts and installed in new 
production engines. We did not change this AD.

Request To Change Mandatory Terminating Action

    Hawkins Aero Engineering, Inc. (Hawkins Aero) requested that the 
mandatory terminating action be changed to allow for installation of CT

[[Page 52173]]

blade P/Ns approved by the FAA in the future. The reason for this 
request is that P&WC and various parts manufacturer approval companies 
may develop new blade designs. Adding language that would allow for 
installation of newly approved blades in the future would avoid having 
to revise this AD.
    We do not agree. We cannot approve P/Ns that do not exist. We did 
not change this AD.

Request To Change Referenced SB and P/N

    One commenter requested that we remove P&WC SB No. PT6A-72-1669 and 
CT blade, P/N 3072791-01, from this AD. The commenter states that this 
SB introduces CT blade, P/N 3072791-01, which is no longer available. 
The commenter suggests that in this AD, to avoid confusion when an 
operator reviews engine repair records to determine SB compliance, we 
should mention only P&WC SB No. PT6A-72-1727, which introduces single 
crystal CT blade, P/N 3072791-02.
    We partially agree. We agree that referencing P&WC SB No. PT6A-72-
1669 in this AD may introduce some confusion as to what P/Ns are 
mandated for installation.
    We disagree with removing all references to P&WC SB No. PT6A-72-
1669 from this AD because this SB contains instructions on performing 
the optional metallurgical examination cited in paragraph 
(e)(1)(iii)(B) of this AD.
    We disagree with removing all references to single crystal CT 
blade, P/N 3072791-01, because it is still acceptable for installation 
even though it is no longer in production.
    We made the following change to the Credit for Previous Actions 
paragraph of this AD: ``If you performed a metallurgical examination of 
single crystal CT blades in accordance with P&WC SB No. PT6A-72-1669, 
Revision 9, dated June 28, 2013, or earlier versions, you met 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.''

Request To Change the Number of Stated Fatalities

    Hawkins Aero requested that we re-evaluate the stated number of 
fatalities that have been associated with CT blade failures. Hawkins 
Aero then provided a brief synopsis of recent fatal incidents involving 
CT blade failures and associated forced landings that provide a 
different number than what was published in the SNPRM (79 FR 26901, May 
12, 2014).
    We partially agree. We agree that we should be accurate in what we 
report. We disagree that we must identify fatalities to demonstrate the 
need for the AD. We changed the justification statement in the Summary 
and Unsafe Condition paragraphs to state that ``This AD was prompted by 
several incidents of CT blade failure, causing power loss, and engine 
failure.''

Request To Change the Costs of Compliance

    One commenter requested that we re-evaluate the costs of 
compliance. The commenter states that the cost of performing the HSI, 
other than the cost of the blades, was not considered. The commenter 
also indicated that the hidden cost of installing the post-SB blades 
has not been revealed. The replacement single crystal CT blades have a 
hard time life limit of 10,000 hours, whereas the CT blades that are 
being replaced do not. The post-SB blades have a lower stretch 
inspection interval of 4,000 hours compared to 5,000 for pre-SB blades.
    We do not agree. The cost of compliance calculation includes the 
initial work and parts costs associated with removing the unsafe 
condition. It does not include costs associated with normal scheduled 
maintenance. We did not change this AD.

Request To Approve Alternate Methods of Compliance (AMOCs)

    Hawkins Aero requested that we approve AMOCs to this AD.
    We do not agree. This AD sets forth our required method of 
compliance to correct the specified unsafe condition. Operators may 
request AMOCs to this AD using the procedures below. We did not change 
this AD.

Request To Change Nomenclature

    Hawkins Aero requested that each time we reference the single 
crystal CT blades in this AD we use the nomenclature ``P&WC single 
crystal CT blade P/N's 3072791-01 and 3072791-02.'' The commenter 
states that ``In several locations within the SNPRM the FAA has 
referred to: `single crystal CT blades P/Ns 3072791-01 or 3072791-02,' 
`CT blades, part numbers P/Ns 3072791-01 or 3072791-02,' and `P&WC 
single crystal CT blades P/Ns 3072791-01 or 3072791-02'.''
    We agree. We changed this AD by replacing all references to the 
single crystal CT blades with the nomenclature ``P&WC single crystal CT 
blades, P/Ns 3072791-01 and 3072791-02.''

Request To Clarify Compliance Language

    One commenter requested that we clarify the language in paragraph 
(e)(1)(iii)(A) of this AD with a specific P/N.
    We do not agree. Operators may install any P/N single crystal CT 
blade eligible for installation. We did not change this AD.

Request To Clarify Assumptions

    One commenter requested that we re-evaluate the 1,800 hour 
assumption for a typical hot section interval. The commenter states, 
``Assuming that 1,800 hours is the normal interval for all operators is 
incorrect; some operators have extended intervals up to and including 
On Condition; therefore, stating to perform the AD at next HSI could be 
much longer than the expected 1,800 hours.''
    We do not agree. We did not assume 1,800 hours as a typical HSI 
interval. This AD requires blade examination or replacement at next 
HSI, and not at specific flight-hour or cycles-in-operation intervals, 
precisely due to the wide variety of approved inspection intervals that 
exist for these engines. We did not change this AD.

Conclusion

    We reviewed the available data, including the comments received, 
and determined that air safety and the public interest require adopting 
this AD with the changes described previously. We 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 will 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, if all blades are 
replaced.

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:

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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 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under the 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.

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 adding the following new airworthiness 
directive (AD):

2014-17-08 Pratt & Whitney Canada Corp.: Amendment 39-17961; Docket 
No. FAA-2013-0766; Directorate Identifier 2013-NE-26-AD.

(a) Effective Date

    This AD becomes effective October 8, 2014.

(b) Affected ADs

    None.

(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 that have CT blades installed other than P&WC 
single crystal CT blades, part numbers (P/Ns) 3072791-01 or 3072791-
02, perform the following actions:
    (i) Within 150 operating hours after the effective date of this 
AD, perform a borescope inspection (BSI) of CT blades for engines 
with 500 or more hours time-since-new that have not been previously 
inspected or time-since-last-inspection (TSLI).
    (ii) Thereafter, repeat the inspection in paragraph (e)(1)(i) of 
this AD within 500 flight hours TSLI.
    (iii) During 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 
examination in accordance with paragraph 3.B., Accomplishment 
Instructions, of P&WC Service Bulletin (SB) No. PT6A-72-1669, 
Revision 9, dated June 28, 2013; or
    (C) P&WC single crystal CT blades, P/Ns 3072791-01 or 3072791-
02.
    (2) Reserved.

(f) Mandatory Terminating Action

    Within 36 months after the effective date of this AD, replace 
the complete set of CT blades with P&WC single crystal CT blades, P/
Ns 3072791-01 or 3072791-02.

(g) Credit for Previous Action

    If you performed a metallurgical examination of single crystal 
CT blades before the effective date of this AD in accordance with 
P&WC SB No. PT6A-72-1669, Revision 8, dated January 17, 2013, or 
earlier versions, all of which are not incorporated by reference, 
you have met 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.

(h) Alternative Methods of Compliance (AMOCs)

    The Manager, Engine Certification Office, FAA, may approve AMOCs 
to this AD. Use the procedures found in 14 CFR 39.19 to make your 
request.

(i) Related Information

    (1) For more information about this AD, contact Robert Morlath, 
Aerospace Engineer, Engine Certification Office, FAA, Engine & 
Propeller Directorate, 12 New England Executive Park, Burlington, MA 
01803; phone: 781-238-7154; fax: 781-238-7199; email: 
<a href="/cdn-cgi/l/email-protection#a6d4c9c4c3d4d288c588cbc9d4cac7d2cee6c0c7c788c1c9d0"><span class="__cf_email__" data-cfemail="51233e333423257f327f3c3e233d302539113730307f363e27">[email&#160;protected]</span></a>.
    (2) Refer to Transport Canada Civil Aviation AD CF-2013-21R1, 
dated November 13, 2013, for more information. You may examine the 
MCAI in the AD docket on the Internet at <a href="http://www.regulations.gov/#!documentDetail">http://www.regulations.gov/#!documentDetail</a>;D=FAA-2013-0766-0008.

(j) 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.
    (i) Pratt & Whitney Canada Service Bulletin No. PT6A-72-1669, 
Revision 9, dated June 28, 2013.
    (ii) Reserved.
    (3) 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.
    (4) 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.
    (5) 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: 
<a href="http://www.archives.gov/federal-register/cfr/ibr-locations.html">http://www.archives.gov/federal-register/cfr/ibr-locations.html</a>.

    Issued in Burlington, Massachusetts, on August18, 2014.
Richard P. Warren,
Acting Assistant Directorate Manager, Engine & Propeller Directorate, 
Aircraft Certification Service.
[FR Doc. 2014-20453 Filed 9-2-14; 8:45 am]
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