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

[Federal Register Volume 74, Number 30 (Tuesday, February 17, 2009)]
[Rules and Regulations]
[Pages 7304-7306]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-3041]


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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; 
Amendment 39-15808; AD 2009-04-02]
RIN 2120-AA64


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

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

ACTION: Final rule.

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SUMMARY: The FAA is adopting 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 AD reduces the 
published life limit of those front turbine hubs, from 12,000 cycles-
since-new (CSN) to 9,370 CSN. This AD also removes from service those 
front turbine hubs using a drawdown schedule. This AD results from PW 
updating the low-cycle-fatigue (LCF) life analysis for front turbine 
hubs, P/N 53L601. We are issuing 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: This AD becomes effective March 24, 2009.

ADDRESSES: The Docket Operations office is located at Docket Management 
Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, 
SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-
0001.

FOR FURTHER INFORMATION CONTACT: Mark Riley, Aerospace Engineer, Engine 
Certification Office, FAA, Engine & Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803;

[[Page 7305]]

e-mail: [email protected]; telephone (781) 238-7758; fax (781) 238-
7199.

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 
with a proposed AD. The proposed AD applies to PW4090 and PW4090-3 
turbofan engines with front turbine hub, P/N 53L601, installed. We 
published the proposed AD in the Federal Register on October 10, 2007 
(72 FR 57502). That action proposed to reduce the published life limit 
of those front turbine hubs, from 12,000 CSN to 9,370 CSN. That action 
also proposed to remove from service those front turbine hubs using a 
drawdown schedule.

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 AD, the regulatory evaluation, 
any comments received, and other information. The street address for 
the Docket Operations office (telephone (800) 647-5527) is provided in 
the ADDRESSES section. Comments will be available in the AD docket 
shortly after receipt.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Front Turbine Support P/N 53L601 Not Procurable

    United Airlines and the Air Transport Association state that the 
front turbine hub, P/N 53L601, has a P/N that is only an internal Pratt 
& Whitney P/N, and the part is not procurable. The procurable part is 
the next higher assembly, P/N 53L121. They suggest that both the detail 
and the assembly part numbers be listed in the applicability section to 
cover both identification methods.
    We do not agree. The PW4000 engine manual does not specify a life 
limit for the front turbine hub assembly, P/N 53L121. However, in order 
to provide additional clarification, we will add a reference to the 
front turbine hub assembly, P/N 53L121, similar to what is shown in the 
PW4000 engine manual.

Request To Clarify the Compliance

    Japan Air Lines requests that we clarify that ``last-high-pressure-
turbine overhaul'' in paragraph (f)(2)(ii) of the proposed AD, would 
also include the last-fluorescent-penetrant inspection of the front 
turbine hub, P/N 53L601, which would be a more accurate reference point 
for them to count compliance cycles. The commenter believes this is 
what we intended to state.
    We agree. We changed paragraph (f)(2)(ii) to state that operators 
are to remove the front turbine hub from service at the next engine 
shop visit (ESV), or before the hub accumulates an additional 6,000 
cycles-since-last-fluorescent-penetrant inspection of the front turbine 
hub, whichever occurs first, but not to exceed 12,000 CSN.

Request To Remove 3,370 CSN References From Paragraphs (f)(1) and 
(f)(2)

    One commenter, Pratt & Whitney, requests that we remove the 
references to front turbine hubs with fewer than 3,370 CSN, and hubs 
with 3,370 CSN or more, from compliance paragraphs (f)(1) and (f)(2), 
as they are not needed. The commenter states that there is no need to 
drive removal of parts before they have reached the new published life 
limit of 9,370 CSN.
    We partially agree. We agree there is no need to remove front 
turbine hubs from service before they reached the new published life 
limit of 9,370 CSN. However, the purpose of the 3,370 CSN threshold is 
to identify those parts that can be removed per the specified drawdown 
schedule. We did not change the AD.

Request To Revise Definition of Engine Shop Visit

    Pratt & Whitney, the ATA, and United Airlines request that we 
revise the definition of ``engine shop visit.'' Pratt & Whitney 
recommends compliance during shop visit at front turbine hub exposure, 
and states that their analysis supports this. The ATA and United 
Airlines recommend compliance during shop visit when either the ``E'' 
or ``N'' flange of the engine is separated. They state that compliance 
at all shop visits will cause unnecessary engine teardowns for ``quick 
change'' engines (fan case module refurbishments) and will result in a 
significant cost impact.
    We partially agree. We reviewed Pratt & Whitney's risk analysis and 
agree that we can manage the risk within acceptable levels if we change 
the definition of shop visit to ``The induction of an engine into the 
shop for maintenance involving the separation of any major mating 
engine flange aft of the ``B'' flange, except that the separation of 
engine flanges solely for the purposes of transportation without 
subsequent engine maintenance does not constitute an engine shop 
visit''. We changed the shop visit definition in paragraph (h) of the 
AD.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD with the changes described previously. 
We have determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    We estimate that this AD will affect 94 engines installed on 
airplanes of U.S. registry. We also estimate that it will take about 
101 work-hours per engine to perform the 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 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 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 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); and
    (3) Will not have a significant economic impact, positive or 
negative,

[[Page 7306]]

on a substantial number of small entities under the criteria of the 
Regulatory Flexibility Act.
    We prepared a summary of the costs to comply with this AD and 
placed it in the AD Docket. 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.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the Federal Aviation Administration 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:

2009-04-02 Pratt & Whitney: Amendment 39-15808. Docket No. FAA-2007-
29110; Directorate Identifier 2007-NE-35-AD.

Effective Date

    (a) This airworthiness directive (AD) becomes effective March 
24, 2009.

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, 
(part of assembly P/N 53L121), 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 hub, P/N 53L601. We are issuing 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 hub, P/N 53L601 (part of assembly P/N 
53L121), 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) after the 
effective date of this AD before the front turbine hub accumulates 
9,370 CSN, remove the front turbine hub from service before the 
front turbine hub accumulates 9,370 CSN.
    (ii) For engines that do not have an ESV after the effective 
date of this AD 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-
fluorescent-penetrant inspection of the front turbine hub, 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. 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, do not install or 
reinstall any PW4090 front turbine hub, P/N 53L601, on any engine if 
the hub has accumulated 9,370 CSN or more than 9,370 CSN. Any PW4090 
front turbine hub, P/N 53L601, that is installed or re-installed in 
any engine after the effective date of this AD must be removed from 
service before the hub accumulates 9,370 CSN.

Definition

    (h) For the purposes of this AD, an ``engine shop visit'' is the 
induction of an engine into the shop for maintenance involving the 
separation of any major mating engine flange aft of the ``B'' 
flange, except that the separation of engine flanges solely for the 
purposes of transportation without subsequent engine maintenance 
does not constitute an engine shop visit.

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, (part of 
assembly 53L121-001) is not affected by this AD. Contact Pratt & 
Whitney, 400 Main St., East Hartford, CT 06108; telephone (860) 565-
7700; fax (860) 565-1605, for the service information identified in 
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: [email protected]; 
telephone (781) 238-7758; fax (781) 238-7199, for more information 
about this AD.

    Issued in Burlington, Massachusetts, on February 2, 2009.
Peter A. White,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
 [FR Doc. E9-3041 Filed 2-13-09; 8:45 am]
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