AD 96-05-01

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 95-06-04, amendment 39-9174 (60 FR 15034, March 22, 1995), which is applicable to McDonnell Douglas Model DC-9-80 series airplanes, was published in the Federal Register on September 26, 1995 (60 FR 49525). That action proposed to continue to require the current inspections and replacement of certain suspect horizontal stabilizer primary trim motors. That action also proposed to expand the applicability of the current AD to include additional affected airplanes.

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 support the proposal.

One commenter requests that the proposal be revised to allow operators to conduct a records search, rather than a visual inspection, to determine if the subject motor is installed on the airplane. This commenter, an operator of affected airplanes, states that it tracks the subject motors by the manufacturer's serial number, which enables it to identify quickly the location of any of the subject motors at any given time. Therefore, the commenter considers that, in lieu of requiring it (and possibly other operators) to apply for an alternative method of compliance with the AD, the final rule should provide for this alternative action.

The FAA concurs with the commenter's request. The final rule has been revised to provide for the option of conducting a records search to determine if the motor installed on the airplane is identified with one of the suspect serial numbers.

Two commenters request that the proposed AD be revised to preclude operators from having to reinspect for units that were previously modified and re-identified (i.e., in accordance with Sundstrand Service Bulletin 9590-27-012). One of these commenters points out that these units require an overhaul every 3,500 hours; at that time they are removed from the airplane and, after overhaul, may be installed on a different airplane or placed in spare status (pending installation on another airplane). One commenter points out that the proposed AD does not take into account the situation where a unit originally installed on an airplane subject to AD 95-06-04 may be removed from that airplane and later installed on another airplane that is subject to the proposed AD. If this situation occurs, the commenter is concerned that operators will be required to duplicate inspections and other actions unnecessarily.

The FAA concurs that some clarification is necessary. As for motors modified (and re- identified) in accordance with Sundstrand Service Bulletin 9590-27-012, the final rule allows for their installation on airplanes that are subject to either AD 95-06-04 or this new AD. If a modified unit is installed on any of these airplanes no further action, including any duplicating"re- identification," is required by the AD. In order to make this eminently clear, the FAA has revised paragraphs (a) and (b) of the final rule to specify that, if the trim motor installed on the airplane has been modified previously in accordance with the applicable Sundstrand service bulletin, no further action is required.

As for the possibility of suspect units being installed as spares, the FAA is not certain that this possibility would occur, since the FAA has been advised that apparently all motors affected by AD 95-06-04 have been modified. However, the FAA has added paragraph (c) to the final rule to preclude the future installation, on any airplane, of a motor having one of the suspect serial numbers.

As for duplicating inspections, as discussed above, the FAA has revised the final rule to allow operators to conduct a records search, in lieu of a visual inspection, to determine if the suspect motor is installed. A records search would expedite the determinationas to whether or not a suspect unit is installed; it would also be far less expensive to accomplish than a visual inspection of the airplane.

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 previously described. 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 142 Model DC-9-80 series airplanes of the affected design in the worldwide fleet. The FAA estimates that a total of 73 airplanes of U.S. registry will be affected by this proposed AD.

The inspection of the horizontal stabilizer primary trim motor is expected to take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this requirement is estimated to be $60 per airplane.The inspection specified in this rule previously was required by AD 95-06-04, which was applicable to approximately 13 U.S.-registered airplanes. Based on the figures discussed above, the cost impact of the current inspection requirements of that AD on U.S. operators of those 13 airplanes is estimated to be $780. In consideration of the compliance time and effective date of AD 95-06-04, the FAA assumes that the operators of the 13 airplanes subject to that AD have already initiated the required actions. This new AD action will add no new costs associated with those airplanes.

This new AD is applicable to approximately 60 additional airplanes. Based on the figures discussed above, the new (inspection) costs to U.S. operators that will be imposed by this new AD are estimated to be $3,600. This figure is based on assumptions that no operator of these additional airplanes has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Should an operator elect to replace a suspect motor, that action will require 5 work hours to accomplish, at an average labor rate of $60 per work hour. Required parts will be provided by Sundstrand Electric Power Systems (the manufacturer of the horizontal stabilizer primary trim motors) at no charge to operators. Based on these figures, the cost impact on U.S. operators for the replacement of a suspect motor is estimated to be $300 per airplane.

Should an operator elect to modify a suspect motor, that action will require 4 work hours to disassemble, modify, reassemble, and test the motor (excluding removal and reinstallation of the motor from the airplane). The average labor rate is $60 per work hour. Required parts will be provided by Sundstrand at no charge to operators. Based on these figures, the cost impact on U.S. operators for the modification of a suspect motor is estimated to be $240 per airplane.

Theregulations 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 RulesDocket 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 39-9174 (60 FR 15034, March 22, 1995), and by adding a new airworthiness directive (AD), amendment 39-9525, to read as follows: