Airworthiness Directives; McDonnell Douglas Model MD-11 and MD- 11F Series Airplanes

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 99-NM-173-AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-173-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

As part of its practice of re-examining all aspects of the service experience of a particular aircraft whenever an accident occurs, the FAA has become aware of an incident where arcing occurred during flight at a terminal strip located overhead in the main cabin of a McDonnell Douglas Model MD-11F series airplane. The arcing resulted in sparks landing on a cargo cover, which consequently caught fire. Investigation revealed that the design and installation did not provide adequate clearance between the terminal strips and mounting brackets, which allowed a power feeder cable terminal lug to ground against a terminal strip support bracket. Investigations conducted of other similar installations have revealed the potential for the same type of incident to occur at other specific aircraft locations. This condition, if not corrected, could result in smoke and fire in the main cabin or avionics compartment. The subject area on certain McDonnell Douglas Model MD-11 series airplanes is identical to that on the affected Model MD-11F series airplanes. Therefore, both of these models may be subject to the same unsafe condition. The incident described previously is not considered to be related to an accident that occurred off the coast of Nova Scotia involving a McDonnell Douglas Model MD-11 series airplane. The cause of that accident is still under investigation.

Other Related Rulemaking

The FAA, in conjunction with Boeing and operators of Model MD-11 series airplanes, is continuing to review all aspects of the service history of those airplanes to identify potential unsafe conditions and to take appropriate corrective actions. This proposed airworthiness directive (AD) is one of a series of actions identified during that process. The process is continuing and the FAA may consider additional rulemaking actions as further results of the review become available.

Explanation of Relevant Service Information

The FAA has reviewed and approved McDonnell Douglas Alert Service Bulletin MD11-24A150, dated March 25, 1999, which describes procedures for replacement of the existing terminal strips and supports above the main cabin at station Y=5-32.000 with new terminal strips and supports. The FAA also has reviewed and approved McDonnell Douglas Alert Service Bulletin MD11-24A147, dated March 24, 1999, which describes procedures for installation of spacers between terminal strips and mounting brackets in the avionics compartment. Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the applicable service bulletin described previously.

Cost Impact

There are approximately 136 airplanes listed in McDonnell Douglas Alert Service Bulletin MD11-24A147, dated March 24, 1999, in the worldwide fleet. The FAA estimates that 40 airplanes of U.S. registry would be affected by this proposed action, that would take approximately 3 work hours per airplane to accomplish the proposed installation, and that the average labor rate is $60 per work hour. Required parts would cost approximately $445 per airplane. Based on these figures, the cost impact of the installation proposed by this AD on U.S. operators is estimated to be $25,000, or $625 per airplane. The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. However, the FAA has been advised that manufacturer warranty remedies are available for some labor with accomplishing the proposed actions. Therefore, the future economic cost impact of this rule on U.S. operators may be less than the cost impact figures indicated above. There are approximately 14 airplanes listed in McDonnell Douglas Alert Service Bulletin MD11-24A150, dated March 25, 1999, in the worldwide fleet. Currently, none of these airplanes are on the US Register. However, should an affected airplane be imported and placed on the US Register in the future, it would require approximately 1 work hour to accomplish the proposed modification, at an average labor rate of $60 per work hour. The cost of required parts would be $885 per airplane. Based

on these figures, the cost impact of this modification proposed by this AD would be $945 per airplane.

Regulatory Impact

The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this proposed regulation (1) Is not a ``significant regulatory action'' under Executive Order 12866; (2) Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) If promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

McDonnell Douglas: Docket 99-NM-173-AD.

Applicability: Model MD-11 and MD-11F series airplanes, as listed in McDonnell Douglas Alert Service Bulletin MD11-24A150, dated March 25, 1999, and McDonnell Douglas Alert Service Bulletin MD11-24A147, dated March 24, 1999; certificated in any category.

Note 1: This AD applies to each airplane 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 airplanes 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 (c) 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 electrical arcing caused by power feeder cable terminal lugs grounding against terminal strip support brackets, which could result in smoke and fire in the main cabin or avionics compartment, accomplish the following:

Replacement of Terminal Strips and Supports

(a) For airplanes listed in the effectivity of McDonnell Douglas Alert Service Bulletin MD11-24A150, dated March 25, 1999, on which the modification specified in McDonnell Douglas Service Bulletin MD11-24-085, dated August 1, 1995, has not been accomplished: Within 1 year after the effective date of this AD, replace the existing terminal strips and supports above the main cabin at station Y=5- 32.000 with new terminal strips and supports in accordance with McDonnell Douglas Alert Service Bulletin MD11-24A150, dated March 25, 1999.

Installation of Spacers

(b) For airplanes listed in the effectivity of McDonnell Douglas Alert Service Bulletin MD11-24A147, dated March 24, 1999: Within 6 months after the effective date of this AD, install spacers between terminal strips and mounting brackets in the avionics compartment in accordance with the service bulletin.

Alternative Methods of Compliance

(c) 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, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles ACO.

Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on October 20, 1999. D. L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 99-27947 Filed 10-26-99; 8:45 am] BILLING CODE 4910-13-U