Airworthiness Directives; McDonnell Douglas MD-90-30 Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-90-30 airplanes. For some airplanes, the proposal would require replacing one 3-phase limiter block assembly, 6 current limiters, and hardware for 9 electrical cables with new parts. For other airplanes, this proposal would require inspecting 6 current limiters and 3 spare current limiters and replacing any defective current limiters with new current limiters. These actions are necessary to prevent overheating of the terminal studs on the 3-phase limiter blocks and associated current limiters, which could cause a fire in the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by February 23, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-226-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-226-AD in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data and Service Management, Dept. C1-L5A (D800-0024). This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington or at the FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT:

George Mabuni, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5341; fax (562) 627-5210.

SUPPLEMENTARY INFORMATION:

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 action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-226-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. 2001-NM-226-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports of overheating of the terminal studs on the 3-phase limiter block and associated current limiters on MD-90 airplanes. Investigation has determined that incorrect manufacturing or assembly procedures were used during manufacture of the 3-phase limiter blocks or the current limiters. If the defective 3-phase limiter blocks or current limiters are not replaced, overheating of the terminal studs on the 3-phase limiter blocks and associated current limiters could occur. Overheating of the terminal studs causes the casing of the current limiters attached to the limiter block to melt and deform. Such overheating could cause a fire in the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved McDonnell Douglas Alert Service Bulletin MD90-24A031, Revision 01, dated February 28, 2001, which describes procedures for replacing (1) The 3-phase limiter block assembly, (2) the 6 current limiters and attaching parts located on the limiter block, and (3) hardware for 9 electrical cables attached to the limiter block.

The FAA has also reviewed and approved McDonnell Douglas Alert Service Bulletin MD90-24A043, Revision 01, dated March 12, 2001, which describes procedures for (1) inspecting the 6 current limiters and attaching hardware and the 3 spare current limiters located in the electrical power center and (2) replacing the current limiters which have manufacturing defects with new current limiters. This service bulletin specifies that the actions required by McDonnell Douglas Alert Service Bulletin MD90-24A031, Revision 01, dated February 28, 2001, are to be accomplished prior to or concurrent with those described in McDonnell Douglas Alert Service Bulletin MD90-24A043, Revision 01, dated March 12, 2001.

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 service bulletins described previously, except as indicated below.

Difference Between Proposed Rule and Referenced Service Bulletin

Operators should note that, although the Accomplishment Instructions of the referenced alert service bulletins describe procedures for recording certain data regarding replacement of the 3-phase limiter block assembly and forwarding the data to the FAA, this proposed AD would not require those actions. The FAA does not need this information from operators.

Cost Impact

There are approximately 29 airplanes in the worldwide fleet which are listed in McDonnell Douglas Alert Service Bulletin MD90-24A031, Revision 01, dated February 28, 2001. The FAA estimates that 18 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 3 work hours per airplane to accomplish the actions proposed in paragraph (b) of this AD, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the actions proposed in paragraph (b) of this AD on U.S. operators is estimated to be $5,655, or $195 per airplane.

There are approximately 4 airplanes in the worldwide fleet which are listed in McDonnell Douglas Alert Service Bulletin MD90-24A031, Revision 01, dated February 28, 2001, and are also listed as Group 1 airplanes in McDonnell Douglas Alert Service Bulletin MD90-24A043, Revision 01, dated March 12, 2001. None of those airplanes are on the U.S. registry.

There are approximately 5 airplanes in the worldwide fleet which are listed as Group 2 airplanes in McDonnell Douglas Alert Service Bulletin MD90-24A043, Revision 01, dated March 12, 2001. The FAA estimates that one airplane of U.S. registry would be affected by this proposed AD, that it would take approximately 3 work hours per airplane to accomplish the actions proposed in paragraph (c) of this AD, and that the average labor rate is $65 per work hour. The manufacturer may cover the cost of replacement parts associated with this proposed AD, subject to warranty conditions. Based on these figures, the cost impact of the actions proposed in paragraph (c) of this AD on U.S. operators is estimated to be $195.

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 proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein would not have a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132.

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.