AD 98-19-03

This amendment adopts a new airworthiness directive (AD), applicable to certain Pratt & Whitney PW4000 series turbofan engines, that requires fluorescent penetrant and eddy current inspections of 2nd stage high pressure turbine (HPT) rotating airseals for cracks, removal from service of cracked parts, incorporation of improved 2nd stage HPT rotating airseals, and modification of 2nd stage ring segments and vane clusters to increase cooling flow and reduce stress as terminating action to the inspection requirements. This amendment is prompted by reports of 2nd stage HPT rotating airseal cracking. The actions specified by this AD are intended to prevent 2nd stage HPT rotating airseal cracking, which could result in an uncontained engine failure and 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 November 9, 1998.

Final rule.

98-19-03 Pratt & Whitney: Amendment 39-10746. Docket 98-ANE-02-AD.
Applicability: Pratt & Whitney Models PW4052, PW4056, PW4060, PW4060A, PW4062, PW4152, PW4156A, PW4158, PW4460, PW4462, PW4164, and PW4168 turbofan engines, with 2nd stage high pressure turbine (HPT) rotating airseals, Part Numbers (P/N) 50L156 or 50L195, installed. These engines are installed on but not limited to Boeing 747 and 767 series, McDonnell Douglas MD-11 series, and Airbus Industrie A300, A310, and A330 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 (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: Required as indicated, unless accomplished previously.
To prevent 2nd stage HPT rotating airseal cracking, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following:
(a) At the next hot section shop visit after the effective date of this AD, and at each subsequent hot section shop visit, fluorescent penetrant inspect and eddy current inspect 2nd stage HPT rotating airseals for cracks, remove from service cracked airseals, and replace with serviceable parts, in accordance with Pratt & Whitney Alert Service Bulletins (ASBs) No. PW4ENG A72-628, Revision 1, dated February 17, 1998, for models PW4052, PW4056, PW4060, PW4060A, PW4062, PW4152, PW4156A, PW4158,PW4460 and PW4462, and Pratt & Whitney ASB No. PW4G-100-A72-80, Revision 1, dated February 17, 1998, for models PW4164 and PW4168.
(b) For the purpose of this AD, a hot section shop visit is defined as any time the HPT module is disassembled.
(c) Within 6 years after the effective date of this AD, modify 2nd stage ring segments and vane clusters, and install improved 2nd stage HPT rotating airseals in accordance with Pratt & Whitney Service Bulletins (SBs) No. PW4ENG 72-636, dated May 16, 1997, and No. PW4ENG 72-637, dated May 16, 1997, for models PW4052, PW4056, PW4060, PW4060A, PW4062, PW4152, PW4156A, PW4158, PW4460 and PW4462, and Pratt & Whitney ASB No. PW4G-100-72-93, dated May 22, 1997, and No. PW4G-100-72-94, dated May 22, 1997 for the PW4164 and PW4168. Performance of these modifications and installation of the improved 2nd stage HPT rotating airseal constitutes terminating action to the inspection requirements of this AD.
(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 request 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.
(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 requirements of this AD can be accomplished.
(f) The actions required by this AD shall be done in accordance with the following Pratt & Whitney service documents:

Document No
Pages
Revision
Date
ASB No. PW4ENG A72-628
1,2
1
February 17, 1998

3
Original
November 21, 1996

4-9
1
February 17, 1998

10
Original
November 21, 1996

11-22
1
February 17, 1998
0NDIP-894
1-25
Original
November 12, 1996
NDIP-896
1-10
Original
November 7, 1996
Total Pages: 57.

ASB No. PW4G-100-A72-80
1-16
1
February 17, 1998
NDIP-894
1-25
Original
November 12, 1996
NDIP-896
1-10
Original
November 7, 1996
Total Pages: 51.

SB No. PW4ENG 72-636
1-30
Original
May 16, 1997
Total Pages: 30.

SB No. PW4G-100-72-93
1-16
Original
May 22, 1997
Total Pages: 16.

SB No. PW4ENG 72-637
1-15
Original
May 16, 1997
Total Pages: 15.

SB No. PW4G-100-72-94
1-10
Original
May 22, 1997
Total Pages: 10.

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) 565-6600, 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.
(g) This amendment becomes effective on November 9, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to Pratt & Whitney (PW) Models PW4052, PW4056, PW4060, PW4060A, PW4062, PW4152, PW4156A, PW4158, PW4460, PW4462, PW4164, and PW4168 turbofan engines was published in the Federal Register on March 24, 1998 (63 FR 14055). That action proposed to require fluorescent penetrant and eddy current inspections of 2nd stage high pressure turbine (HPT) rotating airseals for cracks, removal from service of cracked parts, incorporation of improved 2nd stage HPT rotating airseals, and modification of 2nd stage ring segments and vane clusters to increase cooling flow and reduce stress as terminating action to the inspection requirements.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
One commenter states that theyhave had no uncontained engine failures following HPT rotating airseal fracture events but makes no comment to the text of the proposed rule.
One commenter notes two typographical errors in the applicability, with the "P" deleted for models PW4060 and PW4462. This final rule corrects those errors in the applicability.
The same commenter also notes that the proposed rule seems to use a different compliance requirement than that pointed out in the applicable Service Bulletin (SB). The proposed rule defines a hot section visit as "any time the HPT Module is disassembled", which is less restrictive than the requirement stated in the SB. The FAA concurs. The FAA has determined that the compliance interval stated in the proposed rule poses less of a burden on the operators, is consistent with the risk assessment assumptions, and maintains the safety level desired.
The same commenter states that the proposed rule does not address fluorescent penetrant inspection (FPI) requirements for new parts with the old P/Ns, and believes the intention is for no FPI inspection requirement. The FAA concurs as there is no intention in the AD to require fluorescent penetrant inspections of new parts.
The same commenter states that there is no applicability reference for the SBs in the proposed rule, and that while it can be implicitly assumed that the SBs required for the 94" engine are only those beginning with PW4ENG (and for the 100" engine those beginning with PW4G), there is currently nothing explicitly stating this. The FAA concurs. The SB versus Engine Model applicability has been clarified in the final rule.
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.
There are approximately 1,720 engines of the affected design in the worldwide fleet. The FAA estimates that 350 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take no additional time to accomplish the required actions. Required parts will cost approximately $57,200 per engine. In addition, these parts will have consumed some portion of their life limits at the time of their removal, so this full cost burden will not be realized. Based on these figures, assuming an average part removal time of 7,000 cycles, the total cost impact of the AD on U.S. operators is estimated to be $10,677,333. Pratt & Whitney has advised the FAA that it has an Industry Support Program that will reimburse operators for unconsumed life in parts that are retired early for cracking. This should eliminate the majority of the financial burden to the operators.
The regulations adopted herein will not have substantial direct effects on the States, on the relationshipbetween 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
AirTransportation, 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 adding the following new airworthiness directive