[Federal Register Volume 65, Number 241 (Thursday, December 14, 2000)]
[Rules and Regulations]
[Pages 78083-78085]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-31537]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-43-AD; Amendment 39-12040; AD 2000-25-06]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan 
Engines.

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule, request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Pratt & Whitney (PW) PW4000 turbofan engines 
with the current design low pressure turbine (LPT) 4th stage air seal 
installed. This action requires, based on engine model, replacement of 
the current design seal with a new design seal, or with a modified 
seal. This amendment is prompted by reports of cracks in LPT 4th stage 
air seals. The actions specified by this AD are intended to reduce 
stresses that could lead to LPT 4th stage air seal cracking, resulting 
in seal fracture, uncontained engine failure, and damage to the 
airplane.

DATES: Effective date December 29, 2000. Comments for inclusion in the 
Rules Docket must be received on or before December 29, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 2000-NE-43-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``[email protected]''. Comments sent via the Internet must contain the 
docket number in the subject line. The service information referenced 
under the caption SUPPLEMENTARY INFORMATION may be obtained from Pratt 
& Whitney, 400 Main St., East Hartford, CT 06108; telephone: (860) 565-
6600, fax: (860) 565-4503. This information may be examined at the FAA, 
New England Region, Office of the Regional Counsel, 12 New England 
Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Tara Goodman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone: (781) 
238-7130; fax: (781) 238-7199.

[[Page 78084]]


SUPPLEMENTARY INFORMATION: The FAA recently received reports of five 
LPT 4th stage air seals found cracked. An investigation revealed that 
the cracking is being caused by excessive axial loads on the air seal. 
The thermal environment and mechanical loads are causing the current 
design LPT 4th stage air seals to grow radially and axially.
    This is causing insufficient distance between the LPT stage 3 disk 
and LPT stage 4 disk, that results in an excessive axial load leading 
to air seal cracks. This action requires, based on engine model, 
replacement of the current design seal with a new design seal, or with 
a modified seal. This amendment is prompted by reports of cracks in LPT 
4th stage air seals. The actions specified by this AD are intended to 
reduce stresses that could lead to LPT 4th stage air seal cracking, 
resulting in seal fracture, uncontained engine failure, and damage to 
the airplane. Pratt & Whitney has issued two relevant Alert Service 
Bulletins, (ASB) No. PW4G-100-A72-155, Revision 1, dated October 27, 
2000, and ASB No. PW4ENG A72-707, Revision 1, dated October 27, 2000. 
The ASB's introduce a new design LPT 4th stage air seal P/N 51N038, and 
provide instructions for modifying the current design air seal P/N 
50N478 to increase service life.

Required Actions

    Since the unsafe condition described is likely to exist or develop 
on other engines of the same type design that are certificated for 
operation in the United States, this AD is being issued to replace, 
based on engine model, the current design seal P/N 50N478 with a new 
design seal P/N 51N038, or modification of the current design seal. 
This AD is also being issued to reduce stresses that could lead to LPT 
4th stage air seal cracking, resulting in seal fracture, uncontained 
engine failure, and damage to the airplane.

Immediate Adoption

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications should identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NE-43-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order (EO) No. 13132.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under EO No. 12866. It has been determined further that this action 
involves an emergency regulation under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979). If it is determined that 
this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, may 
be obtained from the Rules Docket at the location provided under the 
caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new 
airworthiness directive:
    2000-25-06  Pratt & Whitney: Amendment 39-12040. Docket 2000-NE-
43-AD.

    Applicability: This airworthiness directive is applicable to 
Pratt & Whitney (PW) PW4052, PW4056, PW4060, PW4060A, PW4062, 
PW4152, PW4156, PW4156A, PW4158, PW4164, PW4168, PW4168A, PW4460, 
and PW4462 turbofan engines, with low pressure turbine (LPT) 4th 
stage air seal, part number (P/N) 50N478 or P/N 50N478-001 
installed. These engines are installed on but not limited to Boeing 
747, 767, McDonnell Douglas MD-11, Airbus Industrie A300, A310, and 
A330 series airplanes.

    Note 1: This airworthiness directive (AD) applies to each engine 
identified in the preceding applicability provision, regardless of 
whether it has been modified, altered, or repaired in the area 
subject to the requirements of this AD. For engines that have been 
modified, altered, or repaired so that the performance of the 
requirements of this AD is affected, the owner/operator must request 
approval for an alternative method of compliance in accordance with 
paragraph (d) of this AD. The request should include an assessment 
of the effect of the modification, alteration, or repair on the 
unsafe condition addressed by this AD; and, if the unsafe condition 
has not been eliminated, the request should include specific 
proposed actions to address it.

Compliance

    Compliance with this AD is required as indicated, unless already 
done.
    To reduce stresses that could lead to fatigue cracking of the 
LPT 4th stage air seal, resulting in seal fracture, uncontained 
engine failure, and damage to the airplane, do the following:
    (a) If the limits in Table 1 of this AD for 4th stage air seal 
P/N 50N478 or P/N 50N478-001 have been exceeded, replace with a 
serviceable part prior to further flight.
    (b) Replace 4th stage air seal, P/N 50N478 or 50N478-001, with a 
serviceable part, based on engine model, prior to exceeding the 
cycles-since-new (CSN) or cycles-in-

[[Page 78085]]

service (CIS) time limits in Table 1 of this AD.

                                    Table 1.--4th Stage Air Seal Time Limits
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                                     4th stage air seal P/  Cycles-since-new (CSN) on
            Engine model                       N            effective date of this AD            Limit
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(1) PW4052, PW4060, PW4060A,         50N478...............  Fewer than or equal to     8,000 CSN.
 PW4156, and PW4158.                                         8,000 CSN.
(2) PW4056, PW4152, PW4156A, and     50N478...............  Fewer than or equal to     8,000 CSN.
 PW4460, that have incorporated                              8,000 CSN.
 service bulletin (SB) PW4ENG 72-
 657, Revision 1, dated July 19,
 2000.
(3) PW4056, PW4152, PW4156A, and     50N478...............  Fewer than or equal to     4,500 CSN.
 PW4460, that have not incorporated                          4,500 CSN.
 SB PW4ENG 72-657, Revision 1,
 dated July 19, 2000.
(4) PW4062 and PW4462..............  50N478...............  Fewer than or equal to     7,000 CSN.
                                                             7,000 CSN.
(5) PW4164, PW4168, and PW4168A....  (i)50N478 or 50N478-   Fewer than or equal to     4,500 CSN.
                                      001.                   3,000 CSN.
                                     (ii)50N478 or 50N478-  More than 3,000 CSN but    1,500 CIS after the
                                      001.                   fewer than or equal to     effective date of this
                                                             4,500 CSN.                 AD.
                                     (iii) 50N478 or        More than 4,500 CSN but    6,000 CSN.
                                      50N478-001.            fewer than 6,000 SCN.
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    For the purposes of this AD, a serviceable part is defined in 
Table 2 as follows:

                       Table 2.--Serviceable Parts
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             For engine models                    Serviceable  P/N
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(1) PW4052, PW4056, PW4060, PW4060A,        51N038 or 50N478-001
 PW4062, PW4152, PW4156, PW4156A, PW4158,
 PW4460, and PW4462.
(2) PW4164, PW4168, and PW4168A...........  51N038
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Alternative Methods of Compliance

    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Engine Certification Office. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the aircraft to a location where 
the inspection and rework requirements of this AD can be 
accomplished.

Effective Date of This AD

    (f) This amendment becomes effective December 29, 2000.

    Issued in Burlington, Massachusetts, on December 5, 2000.
Diane S. Romanosky,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-31537 Filed 12-13-00; 8:45 am]
BILLING CODE 4910-13-P