Document ID: FAA-2012-0079-0012
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Pratt and Whitney Division Turbofan Engines
Posted Date: 2012-08-24T04:00Z

[Federal Register Volume 77, Number 165 (Friday, August 24, 2012)]
[Rules and Regulations]
[Pages 51459-51462]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-20842]

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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; 
Amendment 39-17148; AD 2012-16-01]
RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney Division Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for Pratt & 
Whitney Division 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 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.

DATES: This AD is effective September 28, 2012.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of September 28, 
2012.

ADDRESSES: 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. 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; 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: James Gray, Aerospace Engineer, Engine 
Certification Office, FAA, 12 New England Executive Park, Burlington, 
MA; phone: 781-238-7742; fax: 781-238-7199; email: 
james.e.gray@faa.gov.

[[Page 51460]]

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an AD that would apply to the specified products. 
That NPRM published in the Federal Register on March 23, 2012 (77 FR 
16967). That NPRM proposed to require removing the affected HPT stage 1 
front hubs from service using a drawdown plan.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the proposal 
and the FAA's response to each comment.

Support for the NPRM

    One commenter, The Boeing Company, supported the contents of the 
proposed AD (77 FR 16967, March 23, 2012), as written.

Request To Modify Applicability

    Commenters United Airlines, United Parcel Service Co. (UPS), Pratt 
& Whitney (P&W), and MNG Airlines requested that part numbers (P/Ns) 
52L301 and 51L201-021 be added to the applicability paragraphs (c)(1) 
and (c)(2) of the proposed AD (77 FR 16967, March 23, 2012). The 
commenters noted that the applicability of the proposed AD is 
inconsistent since it includes some assembly P/Ns and some detail P/Ns.
    We agree. We revised the applicability paragraphs of this AD to 
include the referenced P/Ns for consistency.

Request To Change Compliance Time

    Commenters UPS, MNG Airlines, and Onur Air requested that the 
compliance time be changed to ``at next piece-part exposure after the 
effective date of this AD or before accumulating the number of cycles 
listed in this AD, whichever occurs later.'' MNG Airlines indicated 
that its engines would lose 1,382 flight cycles, which would cost more 
than $1,000,000 and force early shop visits. Onur Air noted that its 
engines would lose 1,300 cycles and it would cause stub life problems 
on other life limited parts. UPS also expressed its concern over the 
increased shop burden from a hub life reduction.
    We do not agree. We determined that removal of the HPT stage 1 
front hubs according to the compliance times in paragraph (f) of this 
AD provides an acceptable level of safety for the fleet. This 
acceptable level of safety would not be maintained if all HPT stage 1 
front hubs were allowed to remain in service until the next piece-part 
exposure above the number of cycles listed in this AD. For this reason, 
we also cannot adjust the compliance time to account for potential stub 
life problems that might occur in the other rotors. We did not change 
the AD.

Request To Reference the PW4000 Engine Manual Chapter 05 Life Limits

    Commenters MNG Airlines and P&W requested that the phrase ``former 
life limits cannot be exceeded'' be added to compliance paragraphs 
(f)(1)(ii) and (f)(2)(ii) of the proposed AD (77 FR 16967, March 23, 
2012), or that some other reference to the PW4000 Engine Manual Chapter 
05 life limits be added when the stage 1 front hub is operating during 
the 1,000 cycle drawdown. United commented that a reference to the 
reduced life limits be included in Chapter 05 of the Airworthiness 
Limitations Section (ALS) of the PW4000 Engine Manual.
    We do not agree. The Chapter 05 life limits cannot be exceeded. For 
those hubs beneath the Chapter 05 life limit, this AD requires removal 
according to the drawdown schedule in the AD, which is before the 
Chapter 05 limit is reached. This AD's requirements are independent 
from the Chapter 05 life limits in the ALS of the PW4000 Engine Manual. 
We did not change the AD.

Request Revisions to Service Information To Be Incorporated by 
Reference

    P&W, UPS, and United requested revisions to the service information 
that is incorporated by reference in the AD. P&W requested that the AD 
reference the new P&W Alert Service Bulletin (ASB) No. PW4ENG A72-821, 
dated July 6, 2012 and P&W ASB No. PW4G-100-A72-246, dated June 28, 
2012, which address the unsafe condition and contain the affected part 
numbers by serial number for the PW4000-94'' and PW4000-100'' engines. 
UPS also asked that the AD be revised to note that any subsequent 
revision of the service bulletin (SB) can be used for compliance.
    We agree in part. Our proposed AD (77 FR 16967, March 23, 2012), 
referenced the P/N-serial number (S/N) tables of affected parts in the 
old SBs. We agree that we should use the new P&W SBs. We changed 
paragraph (c) of this AD to incorporate the P/N-S/N tables from the new 
P&W ASBs, specifically from P&W ASB No. PW4ENG A72-821, dated July 6, 
2012 and P&W ASB No. PW4G-100-A72-246, dated June 28, 2012.
    We disagree that the AD should be revised to incorporate future 
revisions of an ASB because we do not know the contents of SBs not yet 
published. We did not change the AD based on UPS's comment.

Request To Modify Compliance Wording

    P&W requested that the phrase ``or at the next piece-part exposure 
after the effective date of this AD, whichever occurs first'' be 
removed from the compliance paragraphs (f)(1)(ii) and (f)(2)(ii). P&W 
indicated that, based on the proposed AD, operators may not be able to 
run HPT stage 1 front hubs, identified in paragraphs (c)(1)(i) and 
(c)(1)(ii), that are exposed at piece-part between 17,000 and 18,000 
cycles-since-new (CSN) and HPT stage 1 front hubs, identified in 
paragraphs (c)(2) and (c)(3), that are exposed between 12,700 and 
13,700 CSN, to the full 1,000 cycle drawdown.
    We partially agree. We agree that the AD if adopted as proposed 
could have forced removal of HPT stage 1 front hubs prior to reaching 
18,000 CSN and 13,700 CSN, respectively. We disagree that we should 
remove the at piece-part exposure wording from paragraphs (f)(1)(ii) 
and (f)(2)(ii) of the AD, because HPT stage 1 front hubs that are 
exposed at piece-part after 18,000 CSN and 13,700 CSN should not go 
back into service, even if they have not accumulated an additional 
1,000 cycles in service. We therefore, revised paragraphs (f)(1)(ii) 
and (f)(2)(ii) of the proposed AD (77 FR 16967, March 23, 2012), to 
clarify that these HPT stage 1 front hubs should be removed at the next 
piece-part exposure above 18,000 CSN and 13,700 CSN, respectively, 
rather than at the next piece-part exposure after the effective date of 
the AD. This change is consistent with the installation prohibition for 
HPT stage 1 front hubs in paragraph (g) of this AD.

Request for Allowance for Mixed-Model Management

    United asked that the AD include an allowance for mixed-model 
management.
    We do not agree. The AD does not restrict use of mixed-model 
management. If an operator uses mixed-model management, then 18,000 CSN 
and 13,700 CSN should be used in the calculation for the respective 
engine models included in paragraph (c) of this AD. We did not change 
the AD.

Request To Add Credit for Prior Compliance

    FedEx Express (FedEx) asked that the AD include credit for 
compliance to prior SBs.

[[Page 51461]]

    We do not agree. Operators can take credit for previous actions 
based on paragraph (e) of this AD. We did not change the AD.

Request To Clarify Requirements for P/N 51L901

    FedEx asked that the AD requirements for stage 1 front hub, P/N 
51L901, be clarified. FedEx claimed that the relevant service 
information section of the AD and its applicability are contradictory.
    We do not agree. We reviewed the P/N references and find no 
contradictions between the two sections. We did not change the AD.

Revision to Cost of Compliance

    In reviewing our cost of compliance estimate made in the NPRM (77 
FR 16967, March 23, 2012), we found that our estimate was wrong. 
Specifically, we found that we based our estimate on the number of 
engines installed on airplanes worldwide rather than just on the U.S. 
fleet. Therefore, we changed our estimate to reflect U.S. operators 
only. This change reduced the number of engines affected from 954 to 
289 and the total cost estimate from $23,049,537 to $6,981,578.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the changes described previously. We also determined that 
these changes will not increase the economic burden on any operator nor 
increase the scope of the AD.

Costs of Compliance

    We estimate that this AD would affect 289 engines installed on 
airplanes of U.S. registry. About 183 engines use a 20,000 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 106 
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 AD to U.S. operators is 
$6,981,578.

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

    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, 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):

2012-16-01 Pratt & Whitney Division: Amendment 39-17148; Docket No. 
FAA-2012-0079; Directorate Identifier 2012-NE-06-AD.

(a) Effective Date

    This AD is effective September 28, 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 a high-pressure turbine 
(HPT) stage 1 front hub part number (P/N) listed in Table 1 to 
paragraph (c) of this AD installed.
    (2) PW4156A, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4158, 
PW4460, and PW4462 turbofan engines, including models with any dash 
number suffix, with an HPT stage 1 front hub P/N listed in Table 1 
to paragraph (c) of this AD installed.

                        Table 1 to Paragraph (c)
------------------------------------------------------------------------
 
------------------------------------------------------------------------
P/N 51L601........................  All serial numbers (S/Ns).
P/N 52L401........................  With a S/N not listed in Table 5 of
                                     the Accomplishment Instructions of
                                     Pratt & Whitney Alert Service
                                     Bulletin (ASB) No. PW4ENG A72-821,
                                     dated July 6, 2012.
P/N 51L201, P/N 51L201-001, P/N     All S/Ns.
 51L201-021.
P/N 51L901, P/N 52L301............  With an S/N not listed in Table 7 of
                                     the Accomplishment Instructions of
                                     Pratt & Whitney ASB No. PW4ENG A72-
                                     821, dated July 6, 2012.
------------------------------------------------------------------------

    (3) PW4164, PW4164C, PW4164C/B, PW4168, and PW4168A turbofan 
engines with an HPT stage 1 front hub, P/N 51L901, installed with an 
S/N not listed in Table 3 of the Accomplishment Instructions of 
Pratt & Whitney ASB No. PW4G-100-A72-246, dated June 28, 2012.

(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

[[Page 51462]]

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) 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 above 
18,000 CSN, whichever occurs first.
    (2) For HPT stage 1 front hubs listed in paragraphs (c)(2) 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 above 13,700 CSN, whichever 
occurs first.

(g) Installation Prohibition

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

    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: james.e.gray@faa.gov.

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the following service 
information under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use the following service information to do the 
actions required by this AD, unless the AD specifies otherwise:
    (i) Pratt & Whitney Alert Service Bulletin (ASB) No. PW4ENG A72-
821, dated July 6, 2012.
    (ii) Pratt & Whitney ASB No. PW4G-100-A72-246, dated June 28, 
2012.
    (3) 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.
    (4) You may review 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.
    (5) You may also review the service information that is 
incorporated by reference 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 July 26, 2012.
Peter A. White,
Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-20842 Filed 8-23-12; 8:45 am]
BILLING CODE 4910-13-P