AD 97-19-18

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 88-24-07, Amendment 39-6062 (53 FR 46439, November 17, 1988), which is applicable to AlliedSignal Inc. (formerly AiResearch and Garrett) TSCP700-4B and -5 series auxiliary power units (APUs), was published in the Federal Register on March 18, 1997 (62 FR 12774). That action proposed to eliminate the option of restretching the tie rods, and require removing from service affected disks in accordance with a schedule derived from calculations in AlliedSignal Inc. Service Bulletin (SB) No. TSCP700-49-7266, dated June 16, 1996, replacing affected disks with serviceable parts, and establishing a life limit of 8,000 cycles since new (CSN) for affected disks.

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 (the manufacturer) states thatthe AD should not imply that the tie rod restretch is ineffective, as the manufacturer believes that the tie rod restretch is beneficial in minimizing disk liberation. The FAA concurs that tie rod restretching is beneficial; however, the FAA has determined through analysis that the life limit of affected disks must be reduced to 8,000 CSN regardless of tie rod restretch in order to ensure safe operation.

Three commenters concur with the rule as proposed.

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 100 APUs installed on aircraft of U.S. registry will be affected by this AD, no additional work hours per APU to accomplish the proposed actions if the actions are accomplished during APU overhaul, 8 work hours to accomplish the required actions if the actions are not accomplished during APU overhaul, and that the average labor rate is $60 per work hour. Based on these figures, and that the work would not be performed during overhaul, the total cost impact of the AD on U.S. operators is estimated to be $48,000.

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. 106(g), 40113, 44701.

§ 39.13 (Amended) 2. Section 39.13 is amended by removing Amendment 39-6062 (53 FR 46439, November 17, 1988) and by adding a new airworthiness directive, Amendment 39-10138, to read as follows: