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[Federal Register Volume 80, Number 109 (Monday, June 8, 2015)]
[Proposed Rules]
[Pages 32316-32318]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-13742]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2015-0869; Directorate Identifier 2015-NE-11-AD]
RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for all 
Pratt & Whitney (PW) PW4164, PW4168, PW4168A, PW4164-1D, PW4168-1D, 
PW4168A-1D, and PW4170 turbofan engines. This proposed AD was

[[Page 32317]]

prompted by crack finds in the 6th stage low-pressure turbine (LPT) 
disk. This proposed AD would require removal of affected 6th stage LPT 
disks. We are proposing this AD to prevent failure of the 6th stage LPT 
disk, which could lead to an uncontained disk release, damage to the 
engine, and damage to the airplane.

DATES: We must receive comments on this proposed AD by August 7, 2015.

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 proposed AD, contact 
Pratt & Whitney, 400 Main St., East Hartford, CT 06108; phone: 860-565-
8770; fax: 860-565-4503. 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-2015-
0869; 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 proposed AD, the regulatory evaluation, any comments 
received, and other information. The street address for the Docket 
Office (phone: 800-647-5527) is in the ADDRESSES section. Comments will 
be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Katheryn Malatek, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; phone: 781-238-7747; 
fax: 781-238-7199; email: katheryn.malatek@faa.gov.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this NPRM. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2015-0869; 
Directorate Identifier 2015-NE-11-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this NPRM. We will 
consider all comments received by the closing date and may amend this 
NPRM because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this NPRM.

Discussion

    We received reports of two crack finds in the front and rear knife-
edge seals on the forward arm of the 6th stage LPT disk during a 
scheduled heavy maintenance shop visit. The suspected root cause of the 
cracks is residual stress introduced during knife-edge weld repair. 
This condition, if not corrected, could result in failure of the 6th 
stage LPT disk, which could lead to an uncontained disk release, damage 
to the engine, and damage to the airplane.

Related Service Information Under 1 CFR Part 51

    We reviewed PW Service Bulletin No. PW4G-100-72-252, dated November 
18, 2014. This service information identifies and directs removal of 
the suspect 6th stage LPT disks. This service information is reasonably 
available because the interested parties have access to it through 
their normal course of business or see ADDRESSES for other ways to 
access this service information.

FAA's Determination

    We are proposing this NPRM because we evaluated all the relevant 
information 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 NPRM would require removing certain serial number 6th stage 
LPT disks, part number 50N886.

Costs of Compliance

    We estimate that this proposed AD would affect 18 engines installed 
on airplanes of U.S. registry. We also estimate that no additional 
hours would be required per engine to comply with this proposed AD 
because the engine is already disassembled in the shop when we require 
the part to be removed. The average labor rate is $85 per hour. We 
estimate that 6 of the engines will require replacement parts during an 
LPT shop visit, and that the prorated replacement parts cost would be 
$108,800 per engine. Based on these figures, we estimate the cost of 
this proposed AD on U.S. operators to be $652,800.

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 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) 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.

[[Page 32318]]

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: Docket No. FAA-2015-0869; Directorate Identifier 
2015-NE-11-AD.

(a) Comments Due Date

    We must receive comments by August 7, 2015.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all Pratt & Whitney (PW) PW4164, PW4168, 
PW4168A, PW4164-1D, PW4168-1D, PW4168A-1D, and PW4170 turbofan 
engines with 6th stage low-pressure turbine (LPT) disks, part number 
50N886, installed.

(d) Unsafe Condition

    This AD was prompted by crack finds in the 6th stage LPT disk. 
We are issuing this AD to prevent failure of the 6th stage LPT disk, 
which could lead to an uncontained disk release, damage to the 
engine, and damage to the airplane.

(e) Compliance

    Comply with this AD within the compliance times specified, 
unless already done. At the next LPT shop visit after the effective 
date of this AD, remove from service 6th stage LPT disks with serial 
numbers listed in the Accomplishment Instructions, Table 1, of PW 
Service Bulletin (SB) No. PW4G-100-72-252, dated November 18, 2014.

(f) Definition

    For the purpose of this AD, an ``LPT shop visit'' is defined as 
maintenance which involves disassembly of the LPT rotor module.

(i) Alternative Methods of Compliance (AMOCs)

    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.

(j) Related Information

    (1) For more information about this AD, contact Katheryn 
Malatek, Aerospace Engineer, Engine Certification Office, FAA, 
Engine & Propeller Directorate, 12 New England Executive Park, 
Burlington, MA 01803; phone: 781-238-7747; fax: 781-238-7199; email: 
katheryn.malatek@faa.gov.
    (2) PW SB No. PW4G-100-72-252, dated November 18, 2014, can be 
obtained from Pratt & Whitney using the contact information in 
paragraph (j)(3) of this proposed rule.
    (3) For service information identified in this proposed rule, 
contact Pratt & Whitney, 400 Main St., East Hartford, CT 06108; 
phone: 860-565-8770; fax: 860-565-4503.
    (4) 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.

    Issued in Burlington, Massachusetts, on May 12, 2015.
Colleen M. D'Alessandro,
Assistant Directorate Manager, Engine & Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2015-13742 Filed 6-5-15; 8:45 am]
 BILLING CODE 4910-13-P
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