Airworthiness Directives; Boeing Model 737-600, 737-700, 737-800, 757-200, and 757-300 Series 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 Boeing Model 737-600, 737-700, 737-800, 757-200, and 757-300 series airplanes. This proposal would require replacing existing video distribution unit (VDU) connectors with new, improved connectors or new wire assemblies (jumpers), and performing related actions, as applicable. This action is necessary to prevent a short circuit in a VDU connector and consequent arcing and damage to wiring within the connector, which could result in damage to adjacent systems or structure and possible smoke or fire in the airplane cabin. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by January 24, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-374-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-374-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 Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Binh V. Tran, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2890; fax (425) 227-1181.

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-374-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-374-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that burned contacts have been found on certain video distribution unit (VDU) connectors installed on certain Boeing Model 737-700 and 737-800 series airplanes. In several cases, the mating connector on the VDU was damaged and, in one case, an insulation blanket near the connector was damaged. Investigation revealed that the burned contacts were caused by the presence of moisture and wire chafing in the backshell boot of the VDU connector. Moisture or chafed wiring may result in a short circuit that may cause internal arcing and damage to wiring within the connector. This condition, if not corrected, could result in damage to adjacent systems or structure, and possible smoke or fire in the airplane cabin.

The same type of VDU connectors is also installed on Boeing Model 737-600, 757-200, and 757-300 series airplanes. While the FAA has not received any reports of burned contacts on these airplane models, the VDU connectors may be subject to the same unsafe condition as those on Boeing Model 737-700 and -800 series airplanes.

Explanation of Relevant Service Information

We have reviewed and approved Boeing Service Bulletin 737-23A1169, Revision 2, dated June 21, 2001. Part 2 of this service bulletin describes procedures for replacing existing VDU connectors with new, improved connectors having better moisture resistance and longer wires, and adding a drip loop to the wiring at the new VDU connectors.

We also have reviewed and approved Boeing Alert Service Bulletin 757-23A0060, Revision 1, dated January 11, 2001; and Boeing Alert Service Bulletin 757-23A0061, Revision 1, dated January 11, 2001. Part 2 of these service bulletins describes procedures for replacing existing VDU connectors with new, improved connectors having better moisture resistance, or—if a drip loop does not exist—with new wire assemblies (jumpers).

Accomplishment of the actions specified in the service bulletins described previously 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 discussed below.

Differences Between Service Bulletins and Proposed AD

Part 1 of the Accomplishment Instructions of the referenced service bulletins describes various interim actions intended to detect or prevent conditions that may lead to a short circuit, until the VDU connectors are replaced with new, improved VDU connectors or wire assemblies, as applicable. However, this proposed AD would not require the interim actions in part 1 of the service bulletins, but only the replacement of the VDU connectors with new, improved connectors or new wire assemblies, as applicable, as described in part 2 of the service bulletins. Mandating the replacement is based on our determination that long-term continued operational safety will be better assured by modifications or design changes to remove the source of the problem, rather than by inspections or other interim actions. Inspections and interim actions may not provide the degree of safety assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with inspections, has led us to consider placing less emphasis on inspections and more emphasis on design improvements. The proposed replacement requirement is consistent with these conditions.

The service bulletins recommend that the part 2 replacement be done as soon as manpower, materials, and facilities are available. We find that such a compliance time would not ensure that the identified unsafe condition is addressed in a timely manner. In developing an appropriate compliance time for this proposed AD, we considered not only the manufacturer's recommendation, but also the degree of urgency associated with addressing the subject unsafe condition. In light of these factors, we find a compliance time of 18 months for completing the proposed actions would be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

Cost Impact

There are approximately 280 airplanes of the affected design in the worldwide fleet. The FAA estimates that 28 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 16 work hours per airplane to accomplish the proposed connector replacement, and that the average labor rate is $60 per work hour. Required parts would cost between $334 and $13,944 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be between $1,294 and $14,904 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. The manufacturer may cover the cost of replacement parts associated with this proposed AD, subject to warranty conditions. Manufacturer warranty remedies may also be available for labor costs associated with this proposed AD. As a result, the costs attributable to the proposed AD may be less than stated above.

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.