Document ID: FAA-2007-29110-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Pratt and Whitney PW4090 and PW4090-3 Turbofan Engines
Posted Date: 2007-10-10T04:00Z

[Federal Register: October 10, 2007 (Volume 72, Number 195)]
[Proposed Rules]               
[Page 57502-57503]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr10oc07-15]                         

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Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

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[[Page 57502]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-29110; Directorate Identifier 2007-NE-35-AD]
RIN 2120-AA64

 
Airworthiness Directives; Pratt & Whitney PW4090 and PW4090-3 
Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for Pratt & Whitney (PW) PW4090 and PW4090-3 turbofan engines with 
front turbine hub, part number (P/N) 53L601, installed. This proposed 
AD would reduce the published life limit of those front turbine hubs 
from 12,000 cycles-since-new (CSN) to 9,370 CSN. This proposed AD would 
also remove from service those front turbine hubs using a drawdown 
schedule. This proposed AD results from PW updating the low-cycle-
fatigue (LCF) life analysis for front turbine hubs, P/N 53L601. We are 
proposing this AD to prevent an uncontained failure of the front 
turbine hub, resulting in an in-flight engine shutdown and possible 
damage to the airplane.

DATES: We must receive any comments on this proposed AD by December 10, 
2007.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     Federal eRulemaking Portal: Go to http://www.regulations.gov
 and follow the instructions for sending your 

comments electronically.
     Mail: Docket Management Facility: U.S. Department of 
Transportation, 1200 New Jersey Avenue, SE., West Building Ground 
Floor, Room W12-140, Washington, DC 20590-0001.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
     Fax: (202) 493-2251.

FOR FURTHER INFORMATION CONTACT: Mark Riley, Aerospace Engineer, Engine 
Certification Office, FAA, Engine & Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803; e-mail: 
mark.riley@faa.gov, telephone (781) 238-7758; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send us any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2007-29110; 
Directorate Identifier 2007-NE-35-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light 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 
with FAA personnel concerning this proposed AD. Using the search 
function of the Web site, anyone can find and read the comments in any 
of our dockets, including, if provided, the name of the individual who 
sent the comment (or signed the comment on behalf of an association, 
business, labor union, etc.). You may review the DOT's complete Privacy 
Act Statement in the Federal Register published on April 11, 2000 (65 
FR 19477-78).

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov
; or in person at the Docket Operations office 

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 Operations office (telephone (800) 647-5527) is 
the same as the Mail address provided in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

Discussion

    PW Engineering updated their life analysis for the front turbine 
hub, P/N 53L601, to incorporate new temperature data in the hub aft 
cavity area. The revised cavity temperatures cause higher than 
anticipated stress levels in the anti-rotation slots of the front 
turbine hub. This results in a reduced published LCF life limit from 
12,000 CSN to 9,370 CSN. This condition, if not corrected, could result 
in uncontained engine failure resulting in an in-flight engine shutdown 
and possible damage to the airplane.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other products 
of this same type design. We are proposing this AD, which would:
     Reduce the published life limit of front turbine hub, P/N 
53L601, from 12,000 CSN to 9,370 CSN; and
     Remove from service those front turbine hubs using a 
drawdown schedule.

Costs of Compliance

    We estimate that this proposed AD would affect 94 engines installed 
on airplanes of U.S. registry. We also estimate that it would take 
about 101 work-hours per engine to perform the proposed actions, and 
that the average labor rate is $80 per work-hour. The prorated cost due 
to a life reduction from 12,000 CSN to 9,370 CSN for the front turbine 
hub is about $66,460 per engine. Based on these figures, we estimate 
the cost of the proposed AD on U.S. operators to be $6,247,240.

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

[[Page 57503]]

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 have 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 that the proposed 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); and
    3. Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD. You may get a copy of this summary at the 
address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Under the authority delegated to me by the Administrator, the 
Federal Aviation Administration 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:

Pratt & Whitney: Docket No. FAA-2007-29110; Directorate Identifier 
2007-NE-35-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by December 10, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Pratt & Whitney (PW) PW4090 and PW4090-3 
turbofan engines with front turbine hub part number (P/N) 53L601, 
installed. These engines are installed on, but not limited to, 
Boeing 777-200 series and 777-300 series airplanes.

Unsafe Condition

    (d) This AD results from PW updating the low-cycle-fatigue (LCF) 
life analysis for front turbine hubs, P/N 53L601. We are proposing 
this AD to prevent an uncontained failure of the front turbine hub, 
resulting in an in-flight engine shutdown and possible damage to the 
airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.
    (f) Remove front turbine hubs, P/N 53L601, from service and 
install a serviceable front turbine hub, as follows:
    (1) For front turbine hubs that have accumulated fewer than 
3,370 cycles-since-new (CSN) on the effective date of this AD, 
remove from service before the hub accumulates 9,370 CSN.
    (2) For front turbine hubs that have accumulated 3,370 or more 
CSN, but fewer than 9,370 CSN on the effective date of this AD, do 
the following:
    (i) For engines that have an engine shop visit (ESV) before the 
front turbine hub accumulates 9,370 CSN, remove the front turbine 
hub from service before the hub accumulates 9,370 CSN.
    (ii) For engines that do not have an ESV before the front 
turbine hub accumulates 9,370 CSN, remove the front turbine hub from 
service at the next ESV, or before the hub accumulates an additional 
6,000 cycles-since-last high pressure turbine overhaul, whichever 
occurs first, but not to exceed 12,000 CSN.
    (3) For front turbine hubs that have accumulated 9,370 or more 
CSN on the effective date of this AD, remove the front turbine hub 
from service at the next ESV, or before the hub accumulates 12,000 
CSN, whichever occurs first.
    (g) This AD establishes a new reduced published life limit for 
the PW4090 turbine front hub, P/N 53L601, of 9,370 CSN, which is 
published in Chapter 05, Time Limits Section 05-10-01, of the PW4000 
Series Engine Shop Manual, P/N 51A751. The following conditions also 
apply:
    (1) Except as provided in paragraphs (f)(2)(ii) and (f)(3) of 
this AD, no alternative retirement lives may be approved for the 
PW4090 front turbine hub, P/N 53L601.
    (2) After the effective date of this AD, PW4090 front turbine 
hub, P/N 53L601, may not be installed or reinstalled on an engine if 
the hub has accumulated more than 9,370 CSN.
    (h) For the purposes of this AD, an ``engine shop visit'' is:
    (1) The induction of an engine into the shop for maintenance 
involving the separation of any major mating engine flange, except 
that for the separation of engine flanges solely for the purposes of 
transportation without subsequent engine maintenance does not 
constitute an engine shop visit; or
    (2) The removal of a disk or spool.

Alternative Methods of Compliance

    (i) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (j) Information on an approved front turbine hub rework 
procedure for increased life is available from the manufacturer. See 
Pratt & Whitney Service Bulletin PW4G-112-72-290, dated July 2, 
2007. The reworked front turbine hub, P/N 53L601-001, is not 
affected by this AD.
    (k) Contact Mark Riley, Aerospace Engineer, Engine Certification 
Office, FAA, Engine & Propeller Directorate, 12 New England 
Executive Park, Burlington, MA 01803; e-mail: mark.riley@faa.gov, 
telephone (781) 238-7758; fax (781) 238-7199, for more information 
about this AD.

    Issued in Burlington, Massachusetts, on October 2, 2007.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
 [FR Doc. E7-19927 Filed 10-9-07; 8:45 am]

BILLING CODE 4910-13-P