AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Pratt & Whitney Canada Corp. (P&WC) turboprop engines. This AD requires
installing a reinforcement liner to the power turbine (PT) containment
ring and, for certain PT containment rings, adding scallops. This AD
was prompted by in-service events involving the perforation of engine
cases as a result of the liberation of PT blades and the fracture/
displacement of the PT containment ring. We are issuing this AD to
prevent uncontained engine failure and damage to the airplane.

DATES: This AD becomes effective August 5, 2014.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of August 5,
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 http://www.regulations.
gov by searching for and locating Docket No. FAA-2013-
1009; 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 Green, Aerospace Engineer,
Engine Certification Office, FAA, Engine & Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803; phone: (781) 238-
7754; fax: (781) 238-7199; email: robert.green@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to the specified products. The
NPRM was published in the Federal Register on January 7, 2014 (79 FR
763). The NPRM proposed to correct an unsafe condition for the
specified products. The MCAI states:

There have been in-service events involving the perforation of
PT6A small series engine cases as a result of the loss of integrity
of Power Turbine (PT) Containment Rings under failure loads.
Perforation of engine cases has been seen to result from the
liberation of PT blades and from fracture/displacement of the PT
Containment Ring itself.

Comments

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

Request To Add Engine Models to the List of Applicable Engines

Friend Aircare requested that we add the engine models listed in
P&WC Service Bulletin (SB) No. 12076, Revision 3, dated January 17,
1992, to the applicability of this AD because that SB requires the same
modification to the PT containment ring assembly.
We agree. We revised paragraph (c) of this AD by adding certain
serial numbers of the following P&WC engine models: PT6A-11, PT6A-11AG,
PT6A-15AG, PT6A-110, PT6A-112, and PT6A-121. We revised paragraph (e)
of this AD to specify use of either P&WC SB No. 12076, Revision 3,
dated January 17, 1992; or P&WC SB No. PT6A-72-A1427, Revision 3, dated
January 27, 2012, as applicable. We revised paragraph (f) of this AD by
adding credit for corrective actions taken in accordance with P&WC SB
No. 12076, Revision 2, dated April 24, 1991, or earlier versions.

Request To Exclude Engines Used on Single-Engine Aircraft

Reabe Spraying Services, Inc. requested that we exclude from
applicability engines used on single-engine aircraft, or aircraft where
the engine has nothing alongside of it that would sustain damage from
release of debris.
We disagree. We consider the uncontained release of engine hardware
to be an unsafe condition. We did not change this AD.

Request To Withdraw the NPRM

Dynamic Aviation requested that the FAA withdraw the NPRM (79 FR
763, January 7, 2014). Dynamic Aviation has not experienced any PT disk
blade failure in 16 years and 800,000 flight hours.
We disagree. There have been in-service events involving the
perforation of PT6A series engine cases as a result of the loss of
integrity of the PT containment rings under failure loads. Perforation
of engine cases has been seen to result from the liberation of PT
blades and from fracture/displacement of the PT containment ring
itself. We consider the release of engine hardware to be an unsafe
condition. This AD requires the incorporation of P&WC SB No. 12076,
Revision 3, dated January 17, 1992, or P&WC SB No. PT6A-72-A1427,
Revision 3, dated January 27, 2012, as applicable, to prevent
uncontained events. We did not change this AD.

Requests To Extend the Period of Compliance

Dynamic Aviation requested that we change the compliance time from
within 24 months after the effective date of this AD, to within 36 to
48 months after the effective date of this AD. Dynamic Aviation said
the extended compliance period would better allow the complete
modification of all engines.
Ameriflight LLC requested that we reconsider the period of
compliance to allow a longer, more realistic timeframe for compliance.
We agree. The compliance period can be increased without an
appreciable risk effect. We revised paragraph (e)(2) of this AD to
read, ``Within 48 months after the effective date of this AD, modify
the existing PT containment ring.''

Request To More Accurately Estimate the Time Required To Modify an
Engine

Several entities requested that the estimated time and costs of
compliance for completing the requirements of this AD more accurately
reflect the actual time required to modify an engine.
We agree. In the NPRM (79 FR 763, January 7, 2014), we based our
estimate of 3 hours to modify an engine on original equipment
manufacturer service information. Further analysis indicates this
estimate is inadequate. We increased the estimated hours required to
modify an engine from 3 hours to 20 hours.

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 1,000 engines installed on
airplanes of U.S. registry. We estimate that it will take about 20
hours per engine to comply with this AD. The average labor rate is $85
per hour. Required parts cost about $1,655 per engine. Based on these
figures, we estimate the cost of this AD on U.S. operators to be
$3,355,000.

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 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

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):