Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

[Federal Register Volume 66, Number 51 (Thursday, March 15, 2001)]
[Rules and Regulations]
[Pages 15024-15026]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-6300]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-43-AD; Amendment 39-12144; AD 2001-05-07]
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 supersedes airworthiness directive (AD) 2000-
25-06, dated December 5, 2000, that is applicable to certain Pratt & 
Whitney (PW) PW4000 turbofan engines with the current design low 
pressure turbine (LPT) 4th stage air seal installed. That AD currently 
requires, based on engine model, replacement of the current design seal 
with a new design seal, or with a modified seal. This amendment adds 
the listing of certain engine serial numbers, to correct an error in 
the applicability section of AD 2000-25-06, for engines affected by PW 
Service Bulletin (SB) PW4 ENG 72-657, Revision 1, dated July, 19, 2000. 
This correction is prompted by comments received on AD 2000-25-06. 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 March 30, 2001. Comments for inclusion in the 
rules docket must be received on or before May 14, 2001.

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 in this AD 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.

SUPPLEMENTARY INFORMATION: On December 5, 2000, the FAA issued AD 2000-
25-06, Amendment 39-12040, (65 FR 78083) dated December 14, 2000 that 
is applicable to certain Pratt & Whitney (PW) PW4000 turbofan engines. 
That AD requires replacement of the current design LPT 4th stage air 
seal with a new design seal, or with a modified seal. That action was 
prompted by reports of cracks in LPT 4th stage air seals. That 
condition, if not corrected, could lead to LPT 4th stage air seal 
cracking, resulting in seal fracture, uncontained engine failure, and 
damage to the airplane.
    Since the issuance of that AD, comments were received on AD 2000-
25-06, stating that an error exists in Table 1 which incorrectly 
includes a limited population of engines affected by PW SB 72-657, 
Revision 1, dated July 19, 2000. The FAA agrees that an error was 
inadvertently made, and that the need to correct Table 1 warrants a new 
superseding final rule, request for comments, to address those comments 
and other comments received.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other PW4000 turbofan engines of the same type 
design, this AD supersedes AD 2000-25-06 to require the correction of 
engine populations affected.

Comments Received

    Interested persons have been afforded an opportunity to comment on 
the Final Rule, Request for Comments, AD 2000-25-06. Due consideration 
has been given to the comments received, and as a result, this 
superseding final rule, request for comments AD is deemed necessary.

Table 1 Error

    Six commenters state that an error exists in Table 1, that includes 
a limited population of engines affected by PW SB 72-657, Revision 1, 
dated July 19, 2000.
    The FAA agrees. The error was made inadvertently. This amendment 
corrects that error by listing certain engine serial numbers in a table 
to clarify applicability for engines affected by PW Service Bulletin 
(SB) PW4 ENG 72-657, Revision 1, dated July, 19, 2000.

Concern for Future AD Revision or AMOC

    One commenter states a concern that with regard to Table 2, future 
air seal designs will warrant an AD revision or an alternative method 
of compliance (AMOC). The commenter requests that this amendment: (1) 
Allow for future air seal part numbers (P/N's), (2) revise Table 1 
accordingly, and (3) eliminate Table 2.
    The FAA does not agree. This AD is applicable to engines with LPT 
4th stage air seals P/N 50N478 or 50N478-001 installed and requires a 
one-time replacement of the air seal, according to Table 2. There is no 
on-going requirement to use only the parts listed in Table 2 in the 
future. Table 2 specifies what is a serviceable part. For PW4000 100-
inch models, the relevant service information published by Pratt & 
Whitney is Service Bulletin (SB) PW4G-

[[Page 15025]]

100-A72-155, Revision 1, dated October 27, 2000. That SB allows 
installation of LPT 4th stage air seals P/N 50N478-001, whereas the AD 
does not. Because SB's are not incorporated by reference in this AD, 
the AD defines a serviceable part. The manufacturer has no plans for 
future air seal designs, which would require new P/N's.

Editorial Comment

    One commenter states that, for clarity, the numbering format of 
Table 1 should be done to the standard for AD's.
    The FAA agrees. This amendment incorporates editorial improvements 
to Table 1.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes as described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

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 
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. Factual 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 13132.

Immediate Adoption of this AD

    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 Executive Order 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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-12040 (65 FR 
78083) dated December 14, 2000, and by adding a new airworthiness 
directive (AD), Amendment 39-12144, to read as follows:

2001-05-07  Pratt & Whitney: Amendment 39-12144. Docket No. 2000-NE-
43-AD. Supersedes AD 2000-25-06, Amendment 39-12040.

    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 (e) 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 LPT 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-service (CIS) time limits in 
Table 1 of this AD as follows:

[[Page 15026]]



                                    Table 1.--4th Stage Air Seal Time Limits
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                                                                               CSN on effective
               Engine model                      4th Stage air seal P/N         date of this AD       Limit
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(1) PW4052, PW4060, PW4060A, PW4156, and   50N478............................  Fewer than or     8,000 CSN.
 PW4158.                                                                        equal to 8,000
                                                                                CSN.
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(2) PW4056, PW4152, PW4156A, and PW4460    50N478............................  Fewer than or     8,000 CSN.
 engines identified in Table 3, that have                                       equal to 8,000
 incorporated service bulletin (SB)                                             CSN.
 PW4ENG 72-657, Revision 1, dated July
 19, 2000.
----------------------------------------------------------------------------------------------------------------
(3) PW4056, PW4152, PW4156A, and PW4460    50N478............................  Fewer than or     4,500 CSN.
 engines identified in Table 3, that have                                       equal to 4,500
 not incorporated SB PW4ENG 72-657,                                             CSN.
 Revision 1, dated July 19, 2000.
----------------------------------------------------------------------------------------------------------------
(4) PW4056, PW4152, PW4156A, and PW4460    50N478............................  Fewer than or     8,000 CSN.
 engines not identified in Table 3.                                             equal to 8,000
                                                                                CSN.
----------------------------------------------------------------------------------------------------------------
(5) PW4062 and PW4462....................  50N478............................  Fewer than or     7,000 CSN.
                                                                                equal to 7,000
                                                                                CSN.
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(6) PW4164, PW4168, and PW4168A..........  50N478 or 50N478-001..............  (i)Fewer than or  4,500 CSN.
                                                                                equal to 3,000
                                                                                CSN.
                                                                               (ii) More than    1,500 CIS after
                                                                                3,000 CSN but     the effective
                                                                                fewer than or     date of this
                                                                                equal to 4,500    AD.
                                                                                CSN.
                                                                               (iii) More than   6,000 CSN.
                                                                                4,500 CSN but
                                                                                fewer than
                                                                                6,000 CSN.
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    (c) 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, PW4062, PW4152, PW4156,      51N038 or 50N478-001.
 PW4156A, PW4158, PW4460, and PW4462.
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(2) PW4164, PW4168, and PW4168A.................................  51N038.
----------------------------------------------------------------------------------------------------------------

    (d) Use Table 3 and Table 1, items (2) and (3) to determine 4th 
stage air seal time limits as follows:

          Table 3.--Engine SN's Affected by PW SB PWENG 72-657
------------------------------------------------------------------------
         Engine model                          Engine SN
------------------------------------------------------------------------
PW4056.......................  P727619, P727623, P727624, P727625
                                P727626, P727627, P727628, P727629,
                                P727630, P727631, P727632, P727633
                                P727634, P727635, P727636, P727637,
                                P727638, P727639.
------------------------------------------------------------------------
PW4152.......................  P724940, P724941.
------------------------------------------------------------------------
PW4156A......................  P724574, P724575.
------------------------------------------------------------------------
PW4460.......................  P733796, P733797, P733798.
------------------------------------------------------------------------

Alternative Methods of Compliance

    (e) 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 (ECO). 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

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

Special Flight Permits

    (f) Special flight permits may be issued in accordance with 
Secs. 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

    (g) This amendment becomes effective March 30, 2001.

    Issued in Burlington, Massachusetts, on March 2, 2001.
David A. Downey,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 01-6300 Filed 3-14-01; 8:45 am]
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