AD 99-14-08

This amendment supersedes an existing airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT9D series turbofan engines, that currently requires initial and repetitive inspections of the sixth stage low pressure turbine (LPT) inner airseal, and modification of the sixth stage LPT inner airseal to reduce the potential for two failure modes. This amendment requires additional repetitive borescope inspections for sixth stage LPT inner airseals found with cracks less than one inch in length. This amendment is prompted by the publication of a revision to a PW service bulletin that introduces the new borescope inspections. The actions specified by this AD are intended to prevent an uncontained failure of the sixth stage LPT inner airseal, which can result in damage to the aircraft.
The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of September 13, 1999.

Final rule.

99-14-08 Pratt & Whitney: Amendment 39-11219. Docket No. 92-ANE-23. Supersedes AD 94-10-09, Amendment 39-8916.
Applicability: Pratt & Whitney (PW) Model JT9D-59A, -70A, -7Q, and -7Q3 turbofan engines, installed on but not limited to Boeing 747 series, McDonnell Douglas DC-10 series, and Airbus A300 series aircraft.
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: Required as indicated, unless accomplished previously.
To prevent an uncontained failure of the sixth stage low pressure turbine (LPT) inner airseal, accomplish the following:
(a) Prior to further flight, rework the sixth stage LPT inner airseal knife edge diameters in accordance with the Accomplishment Instructions of PW Service Bulletin (SB) 5847, Revision 2, dated October 31, 1990.
(b) Prior to further flight, rework the sixth stage LPT inner airseal rear retaining wing in accordance with the Accomplishment Instructions of PW SB 5745, Revision 2, dated October 24, 1990.
Note 2: Rework of the sixth stage LPT inner airseal rear retaining wing in accordance with paragraph (b) of this AD does not exempt sixth stage LPT inner airseals from initial and repetitive inspections in accordance with paragraphs (c)(1), (c)(2), (c)(3), and (c)(4) of this AD.
(c) Eddy current inspect(ECI) or borescope inspect sixth stage LPT inner airseal rear retaining wings for cracks, as follows:
(1) For sixth stage LPT inner airseals identified by part number (P/N) in PW SB No. 5978, Revision 4, dated May 6, 1998, or Revision 3, dated May 20, 1992, with greater than 500 cycles since new (CSN) on the effective date of this AD, accomplish an initial ECI or borescope inspection prior to accumulating more than 250 cycles in service (CIS) after the effective date of this AD, or 500 CIS since the last in-shop fluorescent penetrant inspection (FPI), whichever occurs later, in accordance with the Accomplishment Instructions of PW SB No. 5978, Revision 4, dated May 6, 1998, or Revision 3, dated May 20, 1992.
(2) For sixth stage LPT inner airseals identified by P/N in PW SB No. 5978, Revision 4, dated May 6, 1998, or Revision 3, dated May 20, 1992, with less than or equal to 500 CSN on the effective date of this AD, accomplish an initial ECI or borescope inspection prior to accumulating 750 CSN, or 500 CIS since the last in-shop FPI, whichever occurs later, in accordance with the Accomplishment Instructions of PW SB No. 5978, Revision 4, dated May 6, 1998, or Revision 3, dated May 20, 1992.
(3) For sixth stage LPT inner airseals that meet the continue in service criteria described in PW SB No. 5978, Revision 4, dated May 6, 1998, thereafter, ECI or borescope inspect the sixth stage LPT inner airseal retaining wing for cracks at intervals specified in accordance with the Accomplishment Instructions of PW SB No. 5978, Revision 4, dated May 6, 1998.
(4) Remove cracked sixth stage LPT inner airseals that do not meet the continue in service criteria described in PW SB No. 5978, Revision 4, dated May 6, 1998, and replace with a new, or serviceable sixth stage LPT inner airseal that has been reworked in accordance with paragraph (c) of this AD.
(5) Thereafter, inspect initially, reinspect, and remove from service, if necessary, the replacement sixth stage LPT inner airseals in accordance with paragraphs (c)(1), (c)(2), (c)(3), and (c)(4) of this AD.
(d) Installation of a new, improved 6th stage LPT inner airseal, in accordance with PW SB No. 6054, Revision 1, dated April 24, 1992, constitutes terminating action to the inspections and rework required by this AD.
(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. 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 3: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.
(f) 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 requirements of this AD can be accomplished.
(g) The actions required by this AD shall be done in accordance with the following PW SBs:

Document No.
Pages
Revision
Date
5847
1-4
2
October 31, 1990

5
Original
April 11, 1989

6
2
October 31, 1990

7
Original
April 11, 1989

8
2
October 31, 1990

9
Original
April 11, 1989

10
2
October 31, 1990
Total pages: 10

5978
1
4
May 6, 1998

2
Original
December 19, 1990

3,4
4
May 6, 1998

5
1
October 10, 1991

6
4
May 6, 1998

7-11
1
October 10, 1991

12
4
May 6, 1998

13-18
1
October 10, 1991

19
4
May 6, 1998

20-33
1
October 10, 1991

34
2
April 28, 1992
Total pages: 34

5978
1
3
May 20, 1992

2
Original
December 19, 1990

3,4
2
April 28, 1992

5-11
1
October 10, 1991

12
3
May20, 1992

3-18
1
October 10, 1991

19
3
May 20, 1992

20-33
1
October 10, 1991

34
2
April 28, 1992
Total pages: 34

5745
1-9
2
October 24, 1990
Total pages: 9

6054
1-4
1
April 24, 1992

5-7
Original
November 6, 1991

8
1
April 24, 1992

9-16
Original
November 6, 1991
Total pages: 16

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 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.
(h) This amendment becomes effective on September 13, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR Part 39) by superseding AD 94-10-09, Amendment 39-8916 (59 FR 36047, July 15, 1994), applicable to Pratt & Whitney (PW) JT9D series turbofan engines, was published in the Federal Register on September 9, 1998 (63 FR 48138). That action proposed to add, at intervals not to exceed 50 cycles in service (CIS) since last inspection, additional repetitive borescope inspections for sixth stage LPT inner airseals found with cracks less than one inch in length, in accordance with PW Service Bulletin (SB) No. 5978, Revision 4, dated May 6, 1998.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Two commenters state they are not affected by the proposed rule.
One commenter states that it is not affected by the proposed changes to the current AD.
The FAA has switched the placement of paragraphs (b) and (c) of the proposed rule in order to emphasize that rework of the 6th stage LPT inner airseal rear retaining wing must be performed prior to further flight, but that even after rework, the required ECI or borescope inspections must be performed until installation of an improved 6th stage inner airseal. Therefore, proposed paragraph (b) appears as paragraph (c) in the final rule, and proposed paragraph (c) as paragraph (b). 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 this change. The FAA has determined that this change neither increases the economic burden on any operator nor increases the scope of the AD.
There are approximately 566 engines of the affected design in the worldwide fleet. The FAA estimates that 157 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately2.1 work hours per engine to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $19,782.
The regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
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 DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 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, 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. 39.13 [Amended]
2. Section 39.13 is amended by removing Amendment 39-8916 (59 FR 36047, July 15, 1994) and by adding a new airworthiness directive, Amendment 39-11219, to read as follows: