Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series Turbofan Engines

[Federal Register Volume 67, Number 68 (Tuesday, April 9, 2002)]
[Rules and Regulations]
[Pages 16994-16997]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-8171]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NE-16-AD; Amendment 39-12698; AD 2002-07-04]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), that 
is applicable to Pratt & Whitney (PW) JT9D-7R4 series turbofan engines. 
This amendment requires a one-time inspection of low pressure turbine 
(LPT) 5th stage disks for evidence of blend repairs and mechanical 
damage, and replacement of the affected disks based on the extent of 
those repairs and damage. This amendment is prompted by a report of a 
PW JT9D-7R4G2 turbofan engine that experienced an uncontained failure 
of the LPT 5th stage disk. The actions specified by this AD are 
intended to prevent uncontained failure of the LPT 5th stage disk, due 
to incomplete blend repairs, resulting in in-flight shutdown and damage 
to the airplane.

DATES: Effective date May 14, 2002. The incorporation by reference of 
certain publications listed in the regulations is approved by the 
Director of the Federal Register as of May 14, 2002.

ADDRESSES: The service information referenced in this AD may be 
obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; 
telephone (860) 565-8770; fax (860) 565-4503. This information may be 
examined, by appointment, at the Federal Aviation Administration (FAA), 
New England Region, Office of the Regional Counsel, 12 New England 
Executive Park, Burlington, MA; or at the Office of the Federal 
Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

[[Page 16995]]


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

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an AD that is 
applicable to PW JT9D-7R4 series turbofan engines was published in the 
Federal Register on August 30, 2001 (66 FR 45789). That action proposed 
to require a one-time inspection of low pressure turbine (LPT) 5th 
stage disks for evidence of blend repairs and mechanical damage, and 
replacement of the affected disks based on the extent of those repairs 
and damage, in accordance with PW service bulletin (SB) JT9D-7R4-72-
574, Revision 1, dated June 26, 2001.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Clarification of Areas To Be Inspected

    One commenter states that the areas of inspection are not defined 
for the requirement to remove disks with five or more blended or 
unblended areas of damage by any cause. By not defining the areas of 
inspection, blends or areas of damage anywhere on the disk could be 
counted. The commenter states that blends to remove part markings such 
as TT and TC marks or other blends on fir trees, for example, should 
not be counted toward the five or more rejection limit.
    Another commenter requests clarification of whether a disk may be 
returned to service after five or more blended or unblended damage 
areas are found on the disk but all of the damage is identified as non-
tiebolt damage. The clarification is requested because the blended 
areas or areas of damage called out in the NPRM are not specific. The 
commenter also asks if the determination of acceptance of a disk could 
be done on a case-by-case basis.
    The FAA agrees that the proposal does not specify where on the disk 
to look for blended areas or areas of damage. Therefore the FAA has 
changed paragraph (a)(2) of this final rule to specify that the areas 
to be inspected are the forward and aft web and bore areas. The FAA 
disagrees, however, that disks with five or more areas of damage in the 
forward and aft web areas may be returned to service, even if the 
damage is known to be unrelated to a tiebolt failure during operation. 
Operators may request case-by-case review using the procedure to 
request an Alternative Methods of Compliance, paragraph (c).

Use the Same Wording as the Service Bulletin

    One commenter requests that the FAA use the same wording in the 
compliance instructions for the AD as that which is contained in PW 
Service Bulletin (SB) JT9D-7R4-72-574. Paragraph (a)(1) of the proposal 
states: ``remove from service those LPT 5th stage disks that were 
installed in engines that experienced a tiebolt fracture AND are found 
with blended or unblended damage in the web and bore areas, and replace 
with a serviceable disk.'' In place of the AND above, the SB uses the 
word OR. Using the word AND, implies that the final rule would require 
both tiebolt fracture history and damage to meet replacement criteria.
    The FAA disagrees that any change to Paragrap (a)(1) is necessary, 
but agrees that the final rule could be worded clearer. Paragraph 
(a)(1) of the proposal covered those disks for which the operator knew 
that the damage was due to tiebolt failure. Paragraph (a)(2) of the 
proposal covers those disks for which the tiebolt fracture history is 
unknown. The FAA has changed final rule paragraph (a)(1) to clarify 
that it applies to disks for which there is a known history of tiebolt 
failure in operation.

Exclude Damage Caused by Tierod Removal

    One commenter states that many disks have tierod removal damage on 
the rear side of the disk, due to tierod fracture during disassembly. 
The commenter requests that damage found on the rear side of the disk, 
that is in line with the tierod holes should not be taken into account 
because it is due to tierod removal. The commenter requests that 
alternate inspection requirements be provided that identify the type of 
damage rather than the number of damaged areas.
    The FAA partially agrees. The FAA agrees that the wording should 
include the specification that the tierod damage occurs during 
operation. Therefore, the FAA has changed the wording in final rule 
paragraph (a)(1) to specify that the damage must be due to tiebolt 
fracture during operation. This change is justified because high-energy 
damage to the disk caused by a tiebolt fracture occurs during operation 
rather than during LPT disassembly. However, the FAA does not agree 
that the type of damage, as a result of tiebolt failure during 
operation, should be specified differently than specified in PW SB 
JT9D-7R4-72-574. A tiebolt fracture during operation is capable of 
damaging the aft side of the disk in the web and bore areas. The FAA 
expects operators to use good maintenance practices to prevent damage 
to disks during LPT disassembly. If damage occurs during disassembly, 
the Engine Manual must be used to determine serviceability.

Concern for Engine Manual Revision

    One commenter expresses concern that neither the proposal nor PW SB 
JT9D-7R4-72-574 indicate that the Engine Manual-provided blend repair 
(Section 72-52-11, Repair-01 for JT9D-7R4G2 Engines) will be revised to 
effectively address the tiebolt failure mode and cause. The compliance 
in the proposal does not prevent future blending of the disk web and 
bore when the disk is routed for repair after the one-time mandated 
visual inspection has been completed. The commenter requests that the 
Engine Manual blend repair be referenced in the final rule.
    The FAA agrees that the AD and the Engine Manual should address 
future situations where the one-time mandated visual inspections are 
completed. The manufacturer will include a requirement in the Engine 
Manual to remove from service any LPT 5th stage disk that experienced 
damage to the fore and aft web and bore areas from a fractured tiebolt 
during operation. The intent of the AD is to specify a one-time 
inspection of LPT 5th stage disks. In addition, the AD will more 
clearly state in paragraph (b) of the compliance section that any LPT 
5th stage disk that experiences damage to the fore and aft web and bore 
areas from a fractured tiebolt during operation must be removed from 
service. The repair and serviceability requirements for LPT 5th stage 
disks are not part of the AD.

Revision to Manufacturer's Service Information

    The manufacturer comments that since the publication of the 
proposal, Revision 2 of the SB has been published, which provides a 
revised Figure 2 and a consistent description of the one-time 
inspection rejection criteria.
    The FAA agrees and has added this SB Revision to the incorporation 
by reference.
    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 described 
previously. The FAA has determined that these changes will neither 
increase the economic burden

[[Page 16996]]

on any operator nor increase the scope of the AD.

Economic Analysis

    There are approximately 647 Pratt & Whitney (PW) JT9D-7R4 series 
turbofan engines of the affected design in the worldwide fleet. The FAA 
estimates that 151 engines installed on airplanes of U.S. registry 
would be affected by this AD. The FAA also estimates that it would take 
approximately one work hour per engine to accomplish the proposed 
actions, and that the average labor rate is $60 per work hour. A 
replacement disk would cost approximately $145,260 per engine. Based on 
these figures, the total cost effect of the AD on U.S. operators is 
estimated to be $21,943,320.

Regulatory Analysis

    This final rule does not have federalism implications, as defined 
in Executive Order 13132, because it 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. Accordingly, 
the FAA has not consulted with state authorities prior to publication 
of this final rule.
    For the reasons discussed above, I certify that this action (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) if promulgated, 
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. A final evaluation has been prepared for 
this action and it is contained in the Rules Docket. A copy of it may 
be obtained by contacting the Rules Docket at the location provided 
under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, 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 adding a new airworthiness directive 
to read as follows:

2002-07-04  Pratt & Whitney: Amendment 39-12698. Docket No. 2001-NE-
16-AD.

Applicability

    This airworthiness directive (AD) is applicable to Pratt & 
Whitney (PW) JT9D-7R4D, -7R4D1, -7R4E, -7R4E1, -7R4E4, -7R4G2, and 
7R4H1 series turbofan engines with LPT 5th stage disks, part numbers 
(P/N's) 787905, 787905-001, and 798305 installed. These engines are 
installed on, but not limited to Airbus Industrie A300 and A310 
series, and Boeing 747 and 767 series airplanes.

    Note 1: This 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 (c) 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 at the next 
separation of the LPT module from the engine, unless already done.
    To prevent uncontained failure of the low pressure turbine (LPT) 
5th stage disk due to incomplete blend repairs, resulting in in-
flight shutdown and damage to the airplane, do the following:
    (a) Perform a one-time visual inspection for evidence of blend 
repairs of LPT 5th stage disks, P/N's 787905, 787905-001, and 798305 
in accordance with the Accomplishment Instructions section of PW 
service bulletin (SB) JT9D-7R4-72-574, Revision 1, dated June 26, 
2001, or SB JT9D-7R4-72-574, Revision 2, dated January 21, 2002.
    (1) Remove from service those LPT 5th stage disks that have any 
amount of blended or unblended damage in the forward and aft web and 
bore areas, that was caused by a tiebolt fracture during operation, 
and replace with a serviceable part.
    (2) Remove from service LPT 5th stage disks that have five or 
more areas of blended or unblended damage by any cause in the 
forward and aft web and bore areas and replace with a serviceable 
part.
    (b) After the effective date of this AD, do not install any LPT 
module that contains an LPT 5th stage disk, P/N 787905, 787905-001, 
or 798305 unless that disk has been inspected as specified in 
paragraph (a) of this AD. After the effective date of this AD, do 
not install any LPT 5th stage disk that experiences damage to the 
fore and aft web and bore areas from a fractured tiebolt during 
operation.

Alternative Methods of Compliance

    (c) 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 must submit their request 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.

Documents That Have Been Incorporated by Reference

    (d) The inspection must be done in accordance with the following 
Pratt & Whitney Service Bulletins (SB's):

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            Document No.                       Pages               Revision                   Date
----------------------------------------------------------------------------------------------------------------
SB JT9D-7R4-72-574.................  All......................               1  June 26, 2001.
Total pages: 16
SB JT9D-7R4-72-574.................  1-3......................               2  January 21, 2002.
                                     4-9......................               1  June 26, 2001.
                                     10-12....................               2  January 21, 2002.
                                     13.......................               1  June 26, 2001.
                                     14.......................               2  January 21, 2002.
                                     15-16....................               1  June 26, 2001.
Total pages: 16
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[[Page 16997]]

    This incorporation by reference was approved by the Director of 
the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. Copies may be obtained from Pratt & Whitney, 400 Main St., 
East Hartford, CT 06108; telephone (860) 565-8770; fax (860) 565-
4503. Copies may be inspected, by appointment, at the FAA, New 
England Region, Office of the Regional Counsel, 12 New England 
Executive Park, Burlington, MA; or at the Office of the Federal 
Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

Effective Date

    (e) This amendment becomes effective on May 14, 2002.

    Issued in Burlington, Massachusetts, on March 29, 2002.
Robert G. Mann,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 02-8171 Filed 4-8-02; 8:45 am]
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