AD 94-25-07

This amendment supersedes an existing telegraphic airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT8D series turbofan engines, that currently requires repetitive ultrasonic inspections of a combustion chamber outer case (CCOC) weld, but also allows visual inspection or fluorescent magnetic penetrant inspection (FMPI) of certain CCOC's under specified conditions. This amendment allows ultrasonic inspections only. This amendment is prompted by the greater availability of ultrasonic inspection equipment, which provides a more definitive means of discovering cracks than either visual inspections or FMPI. The actions specified by this AD are intended to prevent rupture of the CCOC, which could result in fire, engine cowl release, or aircraft damage.

Final rule.

94-25-07 Pratt & Whitney: Amendment 39-9091. Docket 93-ANE-81. Supersedes telegraphic airworthiness directive (AD) T89-05-52.
Applicability: Pratt & Whitney (PW) Models JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan engines, with combustion chamber outer case (CCOC), Part Number (P/N) 796761 or 806675. These engines are installed on but not limited to Boeing 727 and 737 series, and McDonnell Douglas DC-9 series aircraft.
Compliance: Required as indicated, unless accomplished previously.
To prevent rupture of the CCOC, which could result in fire, engine cowl release, or aircraft damage, accomplish the following:
(a) Except for CCOC's cited in paragraph (c) of this airworthiness directive (AD), ultrasonically inspect CCOC's installed in engines that have not previously been ultrasonically inspected in accordance with telegraphic AD T89-05-52 for cracks within 10 days or 75 cycles in service (CIS) after the effective date ofthis AD, whichever occurs later, in accordance with paragraph 2.A.(3) and Appendix B of PW Alert Service Bulletin (ASB) No. 5842, Revision 3, dated October 10, 1990.
(b) For CCOC's not installed in engines and not cited in paragraph (c) of this AD, and that have not previously been ultrasonically inspected in accordance with telegraphic AD T89-05-52, ultrasonically inspect for cracks prior to returning the CCOC's to service in accordance with paragraph 2.A.(5) and Appendix C of PW ASB No. 5842, Revision 3, dated October 10, 1990.
(c) For CCOC's, P/N 806675, listed by serial number in Table 1 and paragraph 2.A.(10) of PW ASB No. 5842, Revision 3, dated October 10, 1990, accomplish the following:
(1) At the next removal of the CCOC from the engine after the effective date of this AD, ultrasonically inspect CCOC's for cracks in accordance with paragraph 2.A.(5) and Appendix C of PW ASB No. 5842, Revision 3, dated October 10, 1990.
(2) Remove from service or reinspect CCOC'sin accordance with paragraphs (d) and (e), respectively, of this AD.
(3) Mark CCOC's with new part numbers in accordance with paragraphs 2.A.(5)(c) and 2.A.(11) of PW ASB No. 5842, Revision 3, dated October 10, 1990, that;
(i) have accumulated at least 2,500 CIS since new; and
(ii) exhibit a maximum ultrasonic signal amplitude of less than 40% during the inspection conducted subsequent to 2,500 CIS since new.
(d) Remove from service and replace with a serviceable part CCOC's with maximum ultrasonic signal amplitude determined as follows:
(1) CCOC's with greater than or equal to 360%, prior to further flight, with no ferry flight permitted in accordance with paragraph (i) of this AD below.
(2) CCOC's with less than 360%, but greater than or equal to 240%, prior to further flight, with ferry flight permitted, in accordance with paragraph (i) of this AD below.
(e) Thereafter, ultrasonically inspect CCOC's, P/N's 796761 and 806675, for cracks at intervals determined by maximum ultrasonic signal amplitude, in accordance with paragraph 2.A.(3) and Appendix B of PW ASB No. 5842, Revision 3, dated October 10, 1990, for installed CCOC's; or paragraph 2.A.(5) and Appendix C of PW ASB No. 5842, Revision 3, dated October 10, 1990, for uninstalled CCOC's; as applicable, as follows:
(1) For those CCOC's that meet the criteria described in paragraph (d) of this AD, remove from service and replace with a serviceable part.
(2) For those CCOC's with less than 240%, but greater than or equal to 100%, at intervals of 1,000 CIS since last inspection.
(3) For those CCOC's with less than 100%, but greater than or equal to 40%, at intervals of 2,500 CIS since last inspection.
(4) For those CCOC's with less than 40%, inspect at the next removal of the CCOC from the engine since last inspection.
(f) Mark CCOC's with new P/N's, in accordance with paragraphs 2.A.(5)(c) and 2.A.(11) of PW ASB No. 5842, Revision 3, dated October 10, 1990, that meetthe following criteria:
(1) At least two consecutive ultrasonic inspections have been performed on the CCOC; and
(2) the second inspection was performed in accordance with paragraph (b) of this AD; and
(3) have accumulated at least 2,500 CIS since the first ultrasonic inspection; and
(4) that exhibit a maximum ultrasonic signal amplitude of less than 40% in both inspections.
(g) Remarking of CCOC's with a new P/N in accordance with paragraph (f) of this AD constitutes terminating action to the inspection requirements of this AD.
(h) 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. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office. NOTE: Information concerning the existence of approved alternative method ofcompliance with this AD, if any, may be obtained from the Engine Certification Office.
(i) 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.
(j) The actions required by this AD shall be done in accordance with the following alert service bulletin:

Document No.
Pages
Revision
Date
PW ASB No. 5842
1-17
3
October 10, 1990
Appendix A
1-2
Original
May 26, 1989
Appendix B
1-23
3
October 10, 1990
Appendix C
1-7
Original
May 26, 1989

Total pages: 49.

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. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief 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.
(k) This amendment becomes effective on March 30, 1995.

On March 1, 1989, the Federal Aviation Administration (FAA) issued telegraphic airworthiness directive (AD) T89-05-52, applicable to Pratt & Whitney (PW) JT8D series turbofan engines, which requires repetitive ultrasonic inspections for cracks in the combustion chamber outer case (CCOC). In addition, that telegraphic AD allowed operators who did not have ultrasonic inspection capability to perform visual inspections and fluorescent magnetic penetrant inspections (FMPI) of CCOC's. That action was prompted by reports of two CCOC's, both part number (P/N) 796761, which were found in service with severe cracking and distress at the weld which joins the forward case detail to the rear flange detail. These cracks initiated from an area of incomplete weld created during the manufacturing process and were not detected during the final inspection process. Another CCOC, P/N 806675, is manufactured using a similar process and has the same potential for incomplete welds, but to date have not been found cracked. That condition, if not corrected, could result in rupture of the CCOC, which could result in fire, engine cowl release, or aircraft damage.
Since the issuance of that telegraphic AD, the FAA has received reports that most operators now have the capability to perform ultrasonic inspections, which provides a more definitive means of discovering cracks than either visual inspections or FMPI. In telegraphic AD T89-05-52, reinspection of all CCOC's is required, including reinspection of those CCOC's that exhibited minimal ultrasonic indications during initial inspection. The FAA has determined analytically that CCOC's that exhibit maximum signal amplitudes of less than 40 percent are not life limited at the defined weld area. Therefore, CCOC's that meet this signal criteria for two consecutive ultrasonic inspections may be marked with a new P/N, provided the second ultrasonic inspection is accomplished at least 2,500 cycles in service (CIS) after the first inspection and the second inspection is performed in accordance with Appendix C of PW Alert Service Bulletin (ASB) No. 5842, Revision 3, dated October 10, 1990.
Finally, the FAA has determined that certain CCOC's, P/N 806675, were ultrasonically inspected by PW during the manufacturing process, and therefore do not need to be inspected again until they are accessible in the shop.
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding telegraphic AD T89-05-52 was published in the Federal Register on January 27, 1994 (59 FR 3797). That action proposed to require repetitive ultrasonic inspections of CCOC's for cracks. The proposed AD would also allow CCOC's that meet certain signal criteria for two consecutive ultrasonic inspections to be marked with a new P/N. Once remarked, those CCOC's would not need to meet the repetitive ultrasonic inspection requirements of this AD. Finally, the proposed AD would require ultrasonic inspections on certain CCOC's, P/N 806675, identified by serial number, that were ultrasonically inspected by PW during the manufacturing process, when they are accessible in the shop.
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 that operators should be exempt from the initial 10 days or 75 cycles in service (CIS) after the effective date of this AD, whichever occurs later, ultrasonic inspection if they have already accomplished the inspection in accordance with telegraphic AD T89-05-52. The FAA concurs and paragraphs (a) and (b) of the compliance section of this final rule have been revised in accordance with this comment.
Three commenters state that they agree with eliminating visual inspections and only allowing ultrasonic inspections. The FAA concurs.
One commenter states that the proposed rule will have negligible effect on operations and maintenance. The FAA concurs.
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 on any operator nor increase the scope of the AD.
The FAA estimates that 1,000 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per engine to accomplish the required actions, and that the average labor rate is $55 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $110,000.
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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. 39.13 - [AMENDED]
2. Section 39.13 is amended by adding a new airworthiness directive, Amendment 39-9091, to read as follows: