AD 96-23-07

Effective December 19, 1996.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 19, 1996.

The service information referenced in this AD may be obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Department C1-L51 (2-60). This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Brent Bandley, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone (310) 627-5237; fax (310) 627-5210.

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 certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes series airplanes was published as a notice of proposed rulemaking (NPRM) in the Federal Register on August 27, 1996 (61 FR 44002). That action proposed to require visual/dye penetrant and ultrasonic inspections to detect cracks in the vertical leg of the rear spar lower cap of the wings, and various follow-on actions.

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 supports the proposed AD.

During the development of the proposal for this AD action, the FAA sought input on the technical and economic aspects from the manufacturer, as well as from affected major U.S. operators through the Air Transport Association (ATA) of America. In the process of responding to these initial data-gathering inquiries, the ATA submitted input to the FAA that had come from its member operators. Some of this input was in the form of what appeared to be comments on what the operators presumed would be the proposed AD; these comments went beyond the technical data-gathering aspects of FAA's inquiries. Since it is not the FAA's policy to request that type of input prior to the issuance of a proposed rule, the FAA did not take those comments into consideration when it issued the NPRM for this AD action.

When the NPRM was published in the Federal Register on August 27, 1996, it contained specific language indicating that the FAA was requesting comments from the public on all aspects of the proposed AD. However, neither the ATA nor its member operators resubmitted their earlier (non-technical) comments in response to this request in the NPRM. In such a situation, commenters are advised to resubmit their comments to indicate to the FAA that their previous comments are still relevant to the rule as it actually was proposed. Regardless of the fact that these comments were not submitted to the FAA as part of the formal rulemaking process, the FAA has decided to respond to them in this final rule, since the comments raise issues that may have continuing interest among other members of the affected public.

The following discussion presents the FAA's disposition of each of those comments:

One U.S. operator requests that the threshold for conducting the initial inspection of airplanes that have accumulated more than 15,000 total landings be specified as ``6,000 cycles or 3 years,'' whichever is later. For these airplanes, the proposal specified a threshold of 1,800 landings after the effective date of the AD. The operator states that a later threshold will allow it to schedule the inspections of its affected fleet during regular maintenance intervals. Doing so will minimize the economic burden that this operator would face in terms of consequent downtime and flight schedule interruptions.

The FAA does not concur. The operator provided no technical justification for revising this threshold as requested. Failure of a spar cap is a significant safety issue, and the FAA has determined that the inspection thresholds, as proposed, are warranted, based on the effectiveness of the inspection procedure to detect cracks, and the rate of crack growth in the spar cap at the subject area.

Additionally, the FAA points out that the relevant service information has been available to operators since 1989 (the year that the original version of McDonnell Douglas MD-80 Service Bulletin 57-184 was issued). Operators have had since that time to become aware of the inspection and modification now required by this AD and to add those actions to their individual maintenance plans. In fact, the FAA has been advised that several operators have already done just that.

Further, the FAA does not consider it appropriate to include provisions in an AD that are applicable to a single operator's unique situation. However, paragraph (e) of the final rule does provide affected operators the opportunity to apply for an adjustment of the compliance time if sufficient data are presented to justify such an adjustment.

Request for ``Credit'' if Actions Performed According to Earlier Service Bulletin

Another operator requests that ``credit'' be given to operators who have performed the inspection and/or modification in accordance with the original version of McDonnell Douglas MD-80 Service Bulletin 57-184, dated March 16, 1989. This operator previously accomplished the now-required actions before Revision 1 of that service bulletin was issued on December 22, 1994.

The FAA concurs. Although the proposal cited only Revision 1 of the service bulletin as the appropriate source for service instructions, the FAA finds that the instructions specified in the original version of the service bulletin are equivalent. Therefore, use of either service document is acceptable for compliance with the requirements of this AD. The final rule has been revised to specify this.

One operator questions the FAA's actions in mandating the requirements of McDonnell Douglas MD-80 Service Bulletin 57-184. This operator points out that the service bulletin was the subject of review by the Service Action Requirements (SAR) committee meeting in August 1995. [NOTE: The SAR committee was formed as part of the actions that were originally initiated by the Airworthiness Assurance Working Group (AAWG), Model DC-9/MD-80 Task Group. This committee, comprised of representatives from operators, the manufacturer, and the FAA, conducts reviews of inspection and modification service bulletins that are applicable to aging Model DC-9/MD-80 series airplanes; subsequent to each review, the committee recommends to the FAA which of these service bulletins should be made mandatory in order to reduce the potential for major structural failure of the airplanes.] By a vote of 10 to 1, the committee rejected the need to mandate the bulletin. This operator is not aware of any change in airline experience that would warrant reversing the committee decision and making the service bulletin mandatory via an AD action.

The FAA responds to this comment by stating that, regardless of the outcome of the SAR committee meeting, the FAA is responsible for issuing AD actions at any time in order to correct unsafe conditions that have been identified in airplanes. The FAA considers the potential loss of a rear spar cap to be a significant safety issue warranting AD action. As for additional recent and relevant service experience to further justify this action, the FAA points out that, subsequent to the issuance of the NPRM, one affected operator found an additional crack in the same area that this AD requires to be inspected. In light of this, the FAA maintains that this AD is not only appropriate, but warranted.

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 change previously described. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

There are approximately 489 Model McDonnell Douglas Model DC-9-80 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 306 airplanes of U.S. registry will be affected by this AD, that it will take approximately 26 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $477,360, or $1,560 per airplane.

The cost impact figure discussed above is based on assumptions that no operator 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.

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.

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

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:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.