[Federal Register Volume 77, Number 57 (Friday, March 23, 2012)]
[Proposed Rules]
[Pages 16967-16968]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-6965]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0079; Directorate Identifier 2012-NE-06-AD]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney Division 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 
Pratt & Whitney PW4052, PW4152, PW4056, PW4156A, PW4060, PW4060A, 
PW4060C, PW4062, PW4062A, PW4158, PW4460, PW4462, PW4164, PW4164C, 
PW4164C/B, PW4168, and PW4168A turbofan engines with certain high-
pressure turbine (HPT) stage 1 front hubs installed. This proposed AD 
was prompted by Pratt & Whitney's updated low-cycle-fatigue analysis 
that indicated certain HPT stage 1 front hubs could initiate a crack 
prior to the published life limit. This proposed AD would require 
removing the affected HPT stage 1 front hubs from service using a 
drawdown plan. We are proposing this AD to prevent failure of the HPT 
stage 1 front hub, which could lead to an uncontained engine failure 
and damage to the airplane.

DATES: We must receive comments on this proposed AD by May 22, 2012.

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-
7700; fax: 860-565-1605. You may review copies of the referenced 
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; 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: James Gray, Aerospace Engineer, Engine 
Certification Office, FAA, 12 New England Executive Park, Burlington, 
MA; phone: 781-238-7742; fax: 781-238-7199; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite 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-2012-0079; 
Directorate Identifier 2012-NE-06-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD 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 proposed AD.

Discussion

    A PW2000 field event led Pratt & Whitney to re-evaluate the low-
cycle fatigue analysis of the PW2000 engine and similar engine models, 
including the PW4000 engine. Pratt & Whitney's updated analysis 
indicated that the original grain size requirement specified on the HPT 
stage 1 front hub design drawing was too large, and may not be 
sufficient to meet the published life limits. Although we have not 
received any reports of cracks, parts with the larger grain size may 
initiate a crack prior to the published life limits. This condition, if 
not corrected, could result in failure of the HPT stage 1 front hub, 
which could lead to an uncontained engine failure and damage to the 
airplane.

Relevant Service Information

    We reviewed Pratt & Whitney Service Bulletin (SB) No. PW4ENG 72-
795, Revision 2, dated April 5, 2011, and SB No. PW4G-100-72-220, 
Revision 4, dated September 30, 2011. The SBs list the serial numbers 
of HPT stage 1 front hubs with part number (P/N) 51L901 that are NOT 
affected by this AD. However, all serial numbers of HPT stage 1 front 
hubs with P/N 51L201, P/N 51L201-001, P/N 51L601, and P/N 52L401 are 
affected.

FAA's Determination

    We are proposing this AD 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 proposed AD would require removing the affected HPT stage 1 
front hubs from service using a drawdown plan.

Costs of Compliance

    We estimate that this proposed AD would affect 954 engines 
installed on airplanes of U.S. registry. About 605 engines use a 20,000 
cycles-since new (CSN) life limit for the HPT stage 1 front hub. For 
these engines, we estimate the lost part life to have a value of about 
$25,400 per engine. About 349 engines use a 15,000 CSN life limit. For 
these engines, we estimate the lost life to have a value of about 
$22,013 per engine. Based on these figures, we estimate the total cost 
of the proposed AD to U.S. operators is $23,049,537.

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

[[Page 16968]]

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, 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.

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):

Pratt & Whitney Division: Docket No. FAA-2012-0079; Directorate 
Identifier 2012-NE-06-AD.

(a) Comments Due Date

    We must receive comments by May 22, 2012.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to the following Pratt & Whitney Division 
turbofan engines:
    (1) PW4052, PW4152, and PW4056 turbofan engines, including 
models with any dash number suffix, with the following high-pressure 
turbine (HPT) stage 1 front hub part numbers (P/Ns) installed:
    (i) P/N 51L201, or P/N 51L201-001, or P/N 51L601, or P/N 52L401; 
or
    (ii) P/N 51L901 with a serial number (S/N) not listed in Table 9 
of the Accomplishment Instructions of Pratt & Whitney Service 
Bulletin (SB) No. PW4ENG 72-795, Revision 2, dated April 5, 2011.
    (2) PW4156A, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4158, 
PW4460, and PW4462 turbofan engines, including models with any dash 
number suffix, with the following HPT stage 1 front hub P/Ns 
installed:
    (i) P/N 51L201, or P/N 51L201-001, or P/N 52L401; or
    (ii) P/N 51L901 with an S/N not listed in Table 9 of the 
Accomplishment Instructions of Pratt & Whitney SB No. PW4ENG 72-795, 
Revision 2, dated April 5, 2011.
    (3) PW4164, PW4164C, PW4164C/B, PW4168, and PW4168A turbofan 
engines with an HPT stage 1 front hub P/N 51L901 installed with a S/
N not listed in Table 27A of the Accomplishment Instructions of 
Pratt & Whitney SB No. PW4G-100-72-220, Revision 4, dated September 
30, 2011.

(d) Unsafe Condition

    This AD was prompted by Pratt & Whitney's updated low-cycle-
fatigue analysis that indicated certain HPT stage 1 front hubs could 
initiate a crack prior to the published life limit. This AD requires 
removing the affected HPT stage 1 front hubs from service using a 
drawdown plan. We are issuing this AD to prevent failure of the HPT 
stage 1 front hub, which could lead to an uncontained engine failure 
and damage to the airplane.

(e) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(f) Removal of HPT Stage 1 Front Hubs From Service

    (1) For HPT stage 1 front hubs listed in paragraph (c)(1)(i) and 
(c)(1)(ii) of this AD, do the following:
    (i) If the HPT stage 1 front hub has accumulated 17,000 or fewer 
cycles-since new (CSN) on the effective date of this AD, remove the 
HPT stage 1 front hub from service before accumulating 18,000 CSN.
    (ii) If the HPT stage 1 front hub has accumulated more than 
17,000 CSN on the effective date of this AD, remove the HPT stage 1 
front hub from service before accumulating an additional 1,000 
cycles-in-service (CIS), or at the next piece-part exposure after 
the effective date of this AD, whichever occurs first.
    (2) For HPT stage 1 front hubs listed in paragraphs (c)(2)(i), 
(c)(2)(ii), and (c)(3) of this AD, do the following:
    (i) If the HPT stage 1 front hub has accumulated 12,700 or fewer 
CSN on the effective date of this AD, remove the HPT stage 1 front 
hub from service before accumulating 13,700 CSN.
    (ii) If the HPT stage 1 front hub has accumulated more than 
12,700 CSN on the effective date of this AD, remove the HPT stage 1 
front hub from service before accumulating an additional 1,000 CIS, 
or at the next piece-part exposure after the effective date of this 
AD, whichever occurs first.

(g) Installation Prohibition

    After the effective date of this AD, do not install or reinstall 
into any engine any HPT stage 1 front hubs listed in paragraph 
(c)(1)(i) and (c)(1)(ii) of this AD that are at piece-part exposure 
and exceed 18,000 CSN, or any HPT stage 1 front hubs listed in 
(c)(2)(i), (c)(2)(ii), and (c)(3) of this AD that are at piece-part 
exposure and exceed 13,700 CSN.

(h) Definition

    For the purpose of this AD, piece-part exposure means that the 
part is completely disassembled and removed from the engine.

(i) Alternative Methods of Compliance (AMOCs)

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

(j) Related Information

    (1) For more information about this AD, contact James Gray, 
Aerospace Engineer, Engine Certification Office, FAA, 12 New England 
Executive Park, Burlington, MA; phone: 781-238-7742; fax: 781-238-
7199; email: [email protected].
    (2) For service information identified in this AD, contact Pratt 
& Whitney, 400 Main St., East Hartford, CT 06108; phone: 860-565-
7700; fax: 860-565-1605.
    (3) You may review copies of the referenced 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 March 14, 2012.
Peter A. White,
Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-6965 Filed 3-22-12; 8:45 am]
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