Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. This proposed AD would require replacing the bracket for wire bundle of the fuel quantity indicating system (FQIS), performing a general visual inspection of the FQIS wire bundle for damage, and doing corrective actions if necessary. This proposed AD is prompted by a report of an incorrectly installed FQIS wire bundle. We are proposing this AD to prevent chafing of the FQIS wire(s) in the center fuel tank, which, when combined with a lightning strike or a power wire short to the FQIS wire(s), could result in arcing in the center fuel tank and consequent fuel tank explosion.

DATES:

We must receive comments on this proposed AD by August 23, 2004.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
• By fax: (202) 493-2251.
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

You can get the service information identified in this proposed AD from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You may examine the contents of this AD docket on the Internet at http://dms.dot.gov , or at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Douglas Pegors, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6504; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 200-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-18562; Directorate Identifier 2003-NM-147-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the Docket

You may examine the AD docket in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

During an FAA audit at the manufacturer's facility, a support bracket for the wire bundle of the fuel quantity indicating system (FQIS) was found incorrectly installed in the center fuel tank on a Boeing Model 737-800 series airplane. An FQIS wire bundle attached to a wire support bracket installed in an inverted position could lead to an FQIS wire(s) chafing against the structure. This condition, if not corrected, when combined with a lightning strike or a power wire short to the FQIS wire(s), could result in arching in the center fuel tank and consequent fuel tank explosion.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-28-1190, Revision 1, dated March 27, 2003. The service bulletin describes procedures for replacing the bracket for the FQIS wire bundle with a new, improved bracket; performing a general visual inspection of the FQIS wire bundle for damage; and performing corrective actions, if necessary. The corrective actions include repairing the FQIS wire bundle or replacing the FQIS wire bundle with a new FQIS wire bundle. We have determined that accomplishing the actions specified in the service bulletin will adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require replacing the bracket for the FQIS wire bundle, performing a general visual inspection of the FQIS wire bundle for damage, and doing corrective actions if necessary. The proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

There are about 1,063 airplanes of the affected design in the worldwide fleet. This Ad would affect about 518 airplanes of U.S. registry.

Replacing the bracket would take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Required parts would cost about $186 per airplane. Based on these figures, we estimate the cost of the proposed replacement on U.S. operators to be $130,018, or $251 per airplane.

Inspecting the FQIS wire bundle would take approximately 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, we estimate the cost of the proposed inspection on U.S. operators to be $33,670, or $65 per airplane.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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.