02-22132. Airworthiness Directives; McDonnell Douglas Model 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. This proposal would require a one-time general visual inspection to find wire chafing damage and to determine adequate clearance between the disconnect panel structure and the wires above the aft left lavatory; and corrective actions, if necessary. This action is necessary to prevent damage to certain wires due to contact between the wires and the adjacent structure, which could result in electrical arcing and consequent smoke and fire in the cabin. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by October 15, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-389-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 [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-389-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:

Technical Information: George Mabuni, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone [phone]; fax [phone].

Other Information: Sandi Carli, Airworthiness Directive Technical Editor/Writer; telephone [phone], fax [phone]. Questions or comments may also be sent via the Internet using the following address: [e-mail]. Questions or comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

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-389-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-389-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report of uncommanded deployment of cabin oxygen masks on a McDonnell Douglas MD-88 airplane. The deployment occurred in flight and was limited to the aft lavatories, aft flight attendant seat, and passenger seat masks aft of the aft galley. No cockpit indication lights of the oxygen system/mask deployment illuminated to indicate the deployment. Subsequent inspection revealed burnt wires in the area of the disconnect panel above the aft left lavatory. The cause of the burnt wires was determined to be from chafing against the disconnect panel structure. The chafing condition was attributed to slack in the wires from the module blocks due to contact between a wire bundle and the disconnect panel. Such chafing damage could result in electrical arcing and consequent smoke and fire in the cabin.

The wire installations in the area of the disconnect panel above the aft left lavatory on Model MD-80 airplanes are similar to those installed on Model MD-90 airplanes. Therefore, these models may be subject to the same unsafe condition.

Explanation of Relevant Service Information

We have reviewed and approved Boeing Alert Service Bulletin MD90-24A074, Revision 01, including Appendix A, dated August 8, 2001. The service bulletin describes procedures for a one-time inspection to find wire chafing damage and to determine adequate clearance between the disconnect panel structure and the wires above the aft left lavatory; and corrective actions, if necessary. The corrective actions include securing the wires using tie-wraps to obtain 0.50-inch minimum clearance, if clearance is inadequate; repairing or replacing any damaged wires; and doing a continuity check and test of applicable systems for wires that are repaired or replaced. Accomplishment of the actions specified in the service bulletin 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 bulletin described previously, except as discussed below.

Differences Between Service Information and This Proposed Rule

The service bulletin refers only to an “inspection” to find wire chafing and acceptable clearance between the disconnect panel structure and the wires, but this proposed AD would require a “general visual inspection.” Note 2 has been included in this proposed AD to define this type of inspection.

Although the service bulletin requests that operators report inspection findings of chafing or no chafing to the manufacturer after inspecting the wires, this proposed AD does not contain such a reporting requirement.

Cost Impact

There are approximately 113 airplanes of the affected design in the worldwide fleet. The FAA estimates that 21 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 1 work hour per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspection proposed by this AD on U.S. operators is estimated to be $1,260, or $60 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 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.

§ 39.13

[Amended]

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

McDonnell Douglas: Docket 2001-NM-389-AD.

Applicability: Model MD-90-30 airplanes, as listed in Boeing Alert Service Bulletin MD90-24A074, Revision 01, including Appendix A, dated August 8, 2001; 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 damage to certain wires due to contact between the wires and the adjacent structure, which could result in electrical arcing and consequent smoke and fire in the cabin, accomplish the following:

One-Time Inspection/Corrective Actions

(a) Within 4 months after the effective date of this AD: Do a one-time general visual inspection to find wire chafing damage and to determine adequate clearance between the disconnect panel structure and the wires above the aft left lavatory, per the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-24A074, Revision 01, including Appendix A, dated August 8, 2001. If no damage is found and the clearance is adequate, no further action is required by this AD.

Note 2:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

(1) If no damage is found, but the clearance is inadequate: Before further flight, secure the wires using tie-wraps to obtain 0.50-inch minimum clearance per the service bulletin.

(2) If damage and/or inadequate clearance is found: Before further flight, repair or replace damaged wires with new wires and/or secure the wires using tie-wraps to obtain 0.50-inch minimum clearance, as applicable, per the service bulletin.

(b) Accomplishment of the one-time inspection and corrective actions before the effective date of this AD per Boeing Alert Service Bulletin MD90-24A074, dated May 14, 2001, is considered acceptable for compliance with paragraph (a) of this AD.

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. 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 3:

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 Permit

(d) Special flight permits may be issued in accordance with sections 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 August 20, 2002.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.