AD 95-04-11

This amendment supersedes an existing airworthiness directive (AD), applicable to Textron Lycoming ALF502R series turbofan engines, that currently requires the establishment of a reduced stress rupture retirement life limit for certain third stage turbine disks. This amendment establishes a new increased stress rupture retirement life limit for certain third stage turbine disks used in conjunction with third stage turbine nozzles that have improved cooling effectiveness, expands the applicability by adding the ALF502L series engines, and establishes other new reduced stress rupture retirement life limits. This amendment is prompted by the introduction of an improved design third stage turbine nozzle, and a new reduced stress rupture retirement life limit for certain third stage turbine disks on the ALF502L series engines. The actions specified by this AD are intended to prevent a total loss of engine power, inflight engine shutdown, and possible damage to the aircraft.

Final rule.

95-04-11 Textron Lycoming: Amendment 39-9163. Docket 92-ANE-34. Supersedes AD 90-25-02, Amendment 39-6811.
Applicability: Textron Lycoming ALF502R and ALF502L series turbofan engines installed on but not limited to British Aerospace BAe-146 and Canadair Challenger CL600 aircraft.
Compliance: Required as indicated, unless accomplished previously.
To prevent a total loss of engine power, inflight shutdown, and possible damage to the aircraft, accomplish the following:
(a) Remove from service and replace with a serviceable part third stage turbine disks, Part Numbers (P/N) 2-143-030-05, 2-143-030-08, and 2-143-030-14, as follows:
(1) For disks that have been installed only with third stage turbine nozzles P/Ns 2-141-130-52 or 2-141-120-53, remove from service as follows:
(i) For disks that have accumulated 13,220 or more hours time in service (TIS) since new on the effective date of this AD, within the next 80 hours TIS after the effective date of this AD for the ALF502L engines, or within the next 80 hours TIS after December 11, 1990, (the effective date of AD 90-25-02), for the ALF502R engines, but not to exceed the existing cyclic life limit,
(ii) For disks that have accumulated less than 13,220 hours TIS since new on the effective date of this AD, prior to accumulating more than 13,300 hours TIS since new, but not to exceed the existing cyclic life limit.
(iii) Thereafter, remove disks prior to accumulating more than 13,300 hours TIS since new, but not to exceed the existing cyclic life limit.
(2) For disks that have been installed only with third stage turbine nozzles, P/Ns 2-141-120-57 or 2-141-120-R56, remove from service as follows:
(i) For disks that have accumulated 27,420 or more hours TIS since new on the effective date of this AD, within the next 80 hours TIS after the effective date of this AD, but not to exceed the existing cyclic life limit.
(ii) For disks that have accumulated less than 27,420 hours TIS since new on the effective date of this AD, prior to accumulating more than 27,500 hours TIS since new, but not to exceed the existing cyclic life limit.
(iii) Thereafter, remove disks prior to accumulating more than 27,500 hours TIS since new, but not to exceed the existing cyclic life limit.
(3) For disks that have been installed with both third stage turbine nozzles, P/Ns 2-141-120-52 or 2-141-120-53, and third stage turbine nozzles, P/Ns 2-141-120-57 or 2-141-120- R56, remove from service as follows:
(i) Determine the prorated hourly life limit in accordance with the procedure defined in the Accomplishment Instructions, Section 2.B.(2) of Textron Lycoming Service Bulletin (SB) ALF502 72-0002 (for ALF502R series engines) Revision 22, dated December 23, 1992, or Textron Lycoming SB ALF502 72-0004 (for ALF502L series engines) Revision 11, dated June 17, 1987. From this prorated hourly life limit, subtract 80 hours TIS to determine the compliance threshold for each engine model.
(ii) For disks that have equalled or exceeded the compliance threshold on the effective date of this AD, within the next 80 hours TIS, but not to exceed the existing cyclic life limit.
(iii) For disks that have accumulated less than the compliance threshold on the effective date of this AD, prior to accumulating more than the calculated prorated hourly life limit.
(iv) Thereafter, remove disks at or prior to accumulating the prorated hourly life limit, but not to exceed the existing cyclic life limit.
(b) 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 methods of compliance with thisAD, if any, may be obtained from the Engine Certification Office.
(c) The actions required by this AD shall be done in accordance with the following Textron Lycoming SB's:

Document No.
Pages
Revision
Date
ALF502 72-0002
3
18
December 21, 1989

4-7
22
December 23, 1992

8
21
September 25, 1992

9-10
22
December 23, 1992

11
21
September 25, 1992

12-26
22
December 23, 1992

27
21
September 25, 1992
Total pages: 27.

ALF502 72-0004
1-16
11
June 17, 1987
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 Textron Lycoming, 550 Main Street, Stratford, CT 06497; (203) 385-1470. 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.
(d) This amendment becomes effective on April 3, 1995.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 90-25-02, Amendment 39-6811 (55 FR 48592, November 21, 1990), which is applicable to Textron Lycoming ALF502R series turbofan engines, was published in the Federal Register on March 15, 1993 (58 FR 13711). That action proposed to expand the applicability by adding the ALF502L series. That action would also provide for increased stress rupture retirement life limits for certain third stage turbine disks when used in conjunction with third stage turbine nozzles that have improved cooling effectiveness.
On October 28, 1994, AlliedSignal Inc. purchased the turbine engine product line of Textron Lycoming, but as of this date the anticipated name change on the type certificate for the ALF502L series engines has not occurred.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the one comment received.
The commenter concurs with the rule as proposed.
Since publication of the NPRM, Textron Lycoming has issued Revision 22 to Service Bulletin ALF502 72-0002, dated December 23, 1992, that introduces new part numbered rotor parts and adds pro-rating formulas to include the new parts. The technical content in regard to affected components is unchanged. This final rule has been revised to reference this later revision.
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 900 Textron Lycoming ALF502R and ALF502L series turbofan series engines of the affected design in the worldwide fleet. The FAA estimates that 300 engines installed on aircraft of U.S. registry will be affected by this AD, and that 100 are ALF502L series engines that are subject to the reduction in service life requirement. It is also estimated that to implement the reduction in service life requirement it will take approximately 14 work hours per engine to accomplish the required actions, and that the average labor rate is $55 per work hour. The reduction in service life requirement will cost approximately $30,000 per engine. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $3,077,000.
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: PART39 - 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 removing Amendment 39-6811 (55 FR 48592, November 21, 1990) and by adding a new airworthiness directive, Amendment 39-9163, to read as follows: