[4910-13-P] 

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. 

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-cyclefatigue 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 [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

The Director of the Federal Register approved the incorporation by reference of 

certain publications listed in the AD as of [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

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 
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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; e-mail: james.e.gray@faa.gov. 

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. 
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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. 
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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 
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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 piecepart 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. 
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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. 

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 
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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. 
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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 

1. The authority citation for part 39 continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701. 

§ 39.13 [Amended] 

2. The FAA amends § 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 [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

(b) Affected ADs 

None. 
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(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 51L201-021 

All S/Ns. 

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. 
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(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) of this AD, do the 

following: 

(i) If the HPT stage 1 front hub has accumulated 17,000 or fewer cycles-sincenew (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 
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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; e-mail: 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. 
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(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.