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Proposed Rule

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

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Information about this document as published in the Federal Register.

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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, -700, -700C, -800, and -900 series airplanes. This proposal would require replacement of the existing fueling float switch and conduit assemblies in the main and center fuel tanks with new, improved assemblies. This action is necessary to prevent fluid contamination inside the fueling float switch or chafing of the wiring to the in-tank conduit, which could generate an ignition source and consequent fire and explosion in the fuel tank. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by October 4, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-44-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 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. 2002-NM-44-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.

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FOR FURTHER INFORMATION CONTACT:

Doug Pegors, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1446; fax (425) 227-1181.

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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 2002-NM-44-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. 2002-NM-44-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On February 23, 1999, the FAA issued AD 99-05-12, amendment 39-11060 (64 FR 10213, March 3, 1999), applicable to certain Boeing Model 737-100, -200, -300, -400, and -500 series airplanes. That AD requires removal of the float switch and wiring and inspection of the float switch wiring in the center fuel tank to detect discrepancies, and either reinstallation of existing float switch and wiring, or replacement of the float switch and wiring with a new float switch and wiring. That action also requires installation of Teflon sleeving over the wiring of the float switch. In lieu of the above mentioned requirements, that AD requires deactivation of the float switch, accomplishment of specific fueling procedures, and installation of Caution signs. Any damaged components that were found during the inspections required by that AD were removed and returned to the airplane manufacturer for investigation. Examination of the returned components revealed that the potential for water and fuel contamination of the internal components of the float switch could provide a path for electrical current from the switch to ground. Such a path could generate an ignition source and consequent fire and explosion in the fuel tank.

Actions Since Issuance of AD 99-05-12

Since the issuance of AD 99-05-12, the manufacturer has designed a new, improved fueling float switch and conduit assemblies. The new float switch is more resistant to fuel and moisture contamination. The new electrical cable conduit for the float switch eliminates sharp bends within Start Printed Page 53894the conduit and includes a liner system installed inside the conduit to provide added protection against chafing of the float switch wiring. These improvements are designed to eliminate a potential ignition source in the fuel tanks.

AD 99-05-12 did not include Model 737-600, -700, -700C, -800, and -900 series airplanes in the applicability in anticipation of the availability of redesigned components for those airplanes; therefore, those models are addressed in this proposed AD. The FAA is currently considering replacement of the fueling float switch and conduit assemblies for Model 737-100, -200, -300, -400, and -500 series airplanes, once the redesigned components are available for those models.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin 737-28A1142, dated February 7, 2002, which describes procedures for replacement of the existing fueling float switch and conduit assemblies in the main and center fuel tanks with new, improved assemblies. Each assembly includes a new, improved float switch, and a new conduit assembly with a liner system inside the conduit. 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.

Cost Impact

There are approximately 478 airplanes of the affected design in the worldwide fleet. The FAA estimates that 392 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 56 work hours per airplane to accomplish the proposed replacement in the 2 main fuel tanks, as specified in Work Package I, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the work hours for this proposed replacement on U.S. operators is estimated to be $1,317,120, or $3,360 per airplane.

It would take approximately 23 work hours per airplane to accomplish the proposed replacement in the center fuel tank, as specified in Work Package II, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the work hours for this proposed replacement on U.S. operators is estimated to be $540,960, or $1,380 per airplane.

The kit required to accomplish the proposed replacement in all three fuel tanks would cost approximately $5,116 per airplane.

The cost impact figures discussed above are 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.

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List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

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[Amended]

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

Boeing: Docket 2002-NM-44-AD.

Applicability: Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category, as listed in Boeing Alert Service Bulletin 737-28A1142, dated February 7, 2002.

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 (b) 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 fluid contamination inside the fueling float switch or chafing of the wiring to the in-tank conduit, which could generate an ignition source and consequent fire and explosion in the fuel tank, accomplish the following:

Replacement

(a) Replace the existing fueling float switch and conduit assemblies in the main and center fuel tanks with new, improved assemblies (includes a new float switch and a new conduit assembly with a liner system inside the conduit), at the applicable time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, per Work Packages I and II of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-28A1142, dated February 7, 2002.

Note 2:

Due to the lack of sleeving on the existing electrical wire installations of the center fuel tank, it is recommended that Work Package II be completed before Work Package I.

(1) For airplanes that have accumulated fewer than 5,000 total flight cycles as of the effective date of this AD: Within 2 years after the effective date of this AD.

(2) For airplanes that have accumulated 5,000 total flight cycles or more, but fewer than 10,000 total flight cycles as of the effective date of this AD: Within 1 year after the effective date of this AD.

(3) For airplanes that have accumulated 10,000 total flight cycles or more as of the effective date of this AD: Within 180 days after the effective date of this AD. Start Printed Page 53895

Alternative Methods of Compliance

(b) 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, Seattle 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, Seattle ACO.

Note 3:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permit

(c) 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.

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Issued in Renton, Washington, on August 13, 2002.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 02-21053 Filed 8-19-02; 8:45 am]

BILLING CODE 4910-13-P