AD 99-10-11

This amendment supersedes an existing airworthiness directive (AD), applicable to Pratt & Whitney JT8D-200 series turbofan engines, that currently requires periodic inspection of fan blades for locked rotors and foreign object damage (FOD), unlocking of shrouds if necessary, lubrication of fan blade shrouds, and dimensional restoration of the fan blade leading edge. In addition, that AD requires installation of improved design fan blades as terminating action for the inspections. This AD will reduce the lubrication interval, and require removal of rotors that experience repeat lockups within 225 cycles in service. This supersedure is prompted by reports of twenty-five fan blade failures to date. The actions specified by the AD are intended to prevent fan blade failure, which can result in damage to the aircraft.

Final rule.

99-10-11 Pratt & Whitney: Amendment 39-11164. Docket 96-ANE-02. Supersedes AD 96-23-15, Amendment 39-9821.
Applicability: Pratt & Whitney (PW) Models JT8D-209, -217, -217A, -217C, and -219 turbofan engines that have not incorporated PW Service Bulletin (SB) No. 6193, dated October 31, 1994, or with fan blades, Part Numbers (P/N's) 798821, 798821-001, 808121, 808121-001, 809221, 811821, 851121, 851121-001, 5000021-02,5000021-022, and 5000021-032 installed. These engines are installed on but not limited to McDonnell Douglas MD-80 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 fan blade failure, which can result in damage to the aircraft, accomplish the following:
(a) Inspect fan blades and shrouds, unlock fan blade shrouds, lubricate fan blade shrouds, restore leading edge dimensions, remove from service those fan rotors which experience repeat lockup events within 225 cycles, and modify or install improved design fan blades in accordance with the schedule and procedures described in Parts 1, 2, and 3 of the Accomplishment Instructions of PW Alert Service Bulletin (ASB) No. A6241, Revision 2, dated June 29, 1998.
(b) Modification of fan blades to the improved design configuration or installation of improved design fan blades in accordance with Part 3 of the Accomplishment Instructions of PW ASB No. A6241, Revision 2, dated June 29, 1998, constitutes terminating action to the inspections and maintenance actions described in paragraph (a) of this AD.
(c) For the purpose of this AD, the accomplishment effective date to be used for determination of compliance intervals, as required by Section 2 of PW ASB No. A6241, Revision 2, dated June 29, 1998, is defined as the effective date of this AD.
(d) For the purpose of this AD, "repair" as specified in Part 3, Paragraph A. (1)(b) of the Accomplishment Instructions of PW ASB No. A6241, Revision 2, dated June 29, 1998 is defined as the modification of fan blades to incorporate the revised shroud angle, cutback the leading edge, and restore leading edge dimensions in accordance with Part 3, Paragraph C of the Accomplishment Instructions of PW ASB No. A6241, Revision 2, dated June 29, 1998.(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. 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 2: Information concerning the existence of approved alternative method of compliance with this AD, 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 accomplished in accordance with the following Pratt & Whitney ASB:

Document No.
Pages
Revision
Date
A6241
1-14
Rev. 2
June 29, 1998
Total pages: 14This 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, Publication Department, Supervisor Technical Publications Distribution, M/S 132-30, 400 Main St., East Hartford, CT 06108; telephone (860) 565-7700, 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 June 14, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding airworthiness directive (AD) 96-23-15, Amendment 39-9821 (61 FR 63706, December 2, 1996), applicable to certain Pratt & Whitney (PW) JT8D-200 series turbofan engines, was published in the Federal Register on December 2, 1998 (63 FR 66500). That action proposed to require periodic inspection of fan blades for locked rotors and foreign object damage (FOD), unlocking of shrouds if necessary, lubrication of fan blade shrouds, removal from service of fan rotors which experience repeat lockup events within 225 cycles in service, and dimensional restoration of the fan blade leading edge. In addition, that AD requires installation of improved design fan blades as terminating action for the inspections.
Since the issuance of that AD, the FAA has received reports of 7 additional fan blade failures on engines that had been inspected in accordance with the current AD, bringing the total of reported failures to 25. The fan blades are failing as a result of high cycle fatigue. Contributing factors are foreign object damage (FOD), leading edge erosion, manufacturing discrepancies, and locked fan shrouds. These fan blade failures indicate that the currently mandated fleet management plan is insufficient.
The FAA has reviewed and approved the technical contents of PW Alert Service Bulletin (ASB) No. A6241, Revision 2, dated June 29, 1998, that reduces the lubrication interval, and requires removal of rotors that experience repeat lockups within 225 cycles in service (CIS).
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Three commenters concur with the rule as proposed. Two of these are already in compliance with the rule as proposed.
One commenter suggests that alternate method of compliance (AMOC) approvals for ADs 95-12-19 and 96-23-15 should be applicable to this AD, without requiring additional approval. The proposal only references AMOC approvals to 95-12-19. The FAA does not agree. This AD represents the third AD in a line of ADs addressing the fan blade shroud locking problem on PW JT8D-200 engines. Normally when an AD supersedes a previously issued AD, all AMOC approvals to the superseded AD cease on the effective date of the superseding AD, and operators must either comply with the requirements of the new AD or reapply for a new AMOC approval. On further review of the issue of whether previous AMOC approvals should be allowed to continue in force, the FAA has determined that AMOC approvals for neither of the previous ADs should be allowed to continue in force after the effective date of this AD. The inspection requirements for ASB 6241, Rev. 2, dated June 29, 1998, incorporated in this AD, differ significantly from those of the current AD in that blades that experience repeat lockups within 225 cycles must be removed. Therefore, the FAA has determined to remove proposed paragraph (e) from the final rule. All AMOC approvals issued for either AD 95-12-19 or AD 96-23-15 will cease on the effective date of this AD.
One commenter believes that it is unnecessary to track repeat lockups and remove from service rotors that experience repeat lockups within 225 cycles, because the foreign object damage (FOD) checks and lubrication of the shrouds address the root cause of the problem. The FAA does not concur. Analysis of fan blade fracture events revealed a strong correlation between repeat lockup histories and subsequent fractures. The requirement to track lockup events and remove rotors which experience repeat lockups within 225 cycles is a key part of the fleet management proposal, and is required to provide the full safety benefit of this proposal. A statement clarifying the requirement to remove rotors from service per Part 3 of ASB6241 rev. 2 was added to paragraph (a) ofthis AD. Previously this was stated directly only in the Summary and Supplementary Information sections of the AD. Since comments indicate that operators implied that to be the case, this addition to paragraph (a) does not expand the scope of the AD or add any additional burden to operators.
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 as proposed.
There are approximately 2,650 engines of the affected design in the worldwide fleet. The FAA estimates that 960 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take no additional work hours to perform these inspections except at a shorter lubrication interval. Rework costs for the fan blades are $275 per blade, of which approximately $140 per blade is attributable to this AD action. With the manufacturer's rebate of $50 per blade, the total cost to industry of reworking these blades is $2,750 per engine. The manufacturer estimates that it will take 19 work hours per engine to remove and reinstall the blades. Using labor costs of $60 per work hour, the labor costs to remove and reinstall the blades are $1,140 per engine. Hence, the increased costs generated by this proposed AD on U.S. operators is estimated to be $3,890 per engine, or $3,734,400 to retrofit the remaining 960 engines.
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 USC 106(g), 40113,44701. 39.13 - [AMENDED]
2. Section 39.13 is amended by removing Amendment 39-9821 (61 FR 63706, December 2, 1996) and by adding a new airworthiness directive, Amendment 39-11164, to read as follows: