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Proposed Rule

Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes

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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 all Boeing Model 737-300, -400, and -500 series airplanes. This proposal would require, among other actions, a one-time detailed visual inspection of the fuel quantity indicating system (FQIS) wiring and fuel tubing on the inboard side of the right wing rib wing buttock line (WBL) 227 and on the aft side of stringer No. 13 to determine if clearance exists between the FQIS wire harness and the refuel tube and tube coupling, and to detect any loose or broken refuel tube clamp or bracket or chafing of the FQIS wire harness; and corrective actions, if necessary. This action is necessary to detect and correct chafing and to prevent electrical contact between the FQIS wiring and the surrounding structure, which, in conjunction with another wiring failure outside the fuel tank, could result in fire or explosion of the fuel tank. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by November 2, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-313-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. 2000-NM-313-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:

Sherry Vevea, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1360; 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 notice 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-313-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. 2000-NM-313-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received two reports of chafing of the wire harness of the fuel quantity indicating system (FQIS) in the right main fuel tank inboard of right wing station wing buttock line (WBL) 227. Both of these reports indicated that wires were chafed down to the conductor. Investigation of one of those events revealed that the refuel tube clamp broke due to a preload on the clamp. The refuel tube shifted position, and the refuel tube coupling chafed against the FQIS wire harness. The tube coupling has a knurled surface and a lockwire that, if not located correctly, can chafe the FQIS wiring. A chafed or bare FQIS wire normally operates at five volts and does not constitute an in-tank ignition source without an additional failure condition such as wire bundle shorts outside the fuel tank.

Chafing and arcing between the FQIS wiring and the surrounding structure, in conjunction with another wiring failure outside the fuel tank, could result in fire or explosion of the fuel tank.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin 737-28A1168, dated September 26, 2000. The service bulletin describes procedures for a one-time detailed visual inspection of the FQIS wiring and fuel tubing on the inboard side of the right wing rib WBL 227 and on the aft side of stringer No. 13 to determine if a 3/8-inch clearance exists between the FQIS wire harness and the refuel tube and tube coupling, and to detect any loose or broken refuel tube clamp or bracket or chafing of the FQIS wire harness; and corrective actions, if necessary. The corrective actions, if necessary, involve the following:

  • Readjusting the refuel tube;
  • Relocating the bonding jumper away from the FQIS wiring;
  • Replacing the broken clamp with a new clamp;
  • Repairing the broken bracket or replacing the broken bracket with a new bracket;
  • Securing the loose clamp or bracket;
  • Replacing the wire harness with a new wire harness;
  • Repairing the wire harness;
  • Splicing the wires; and
  • Installing a teflon sleeve. Start Printed Page 58967

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. The proposed AD also would require that operators submit a plan to the FAA that identifies a schedule for compliance with the requirements of the proposed AD and report results of inspection findings to the manufacturer.

Difference Between This Proposed AD and the Service Bulletin

The FAA recognizes that this proposed AD would require entry into the fuel tank, which would require taking the airplane out of service for as much as two days. This lengthy shop visit, as well as the relatively short compliance time (six months) required to accomplish this proposed AD, make it necessary for operators to engage in compliance planning to ensure that, when the deadline for compliance arrives, all of the required actions have been completed on all affected airplanes. Therefore, paragraph (a) of this proposed AD would require that operators submit to the FAA a compliance plan within 15 days after the effective date. This will enable the FAA to verify that all operators will be able to meet the deadlines imposed by this proposed AD.

Interim Action

This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.

Cost Impact

There are approximately 1,974 airplanes of the affected design in the worldwide fleet. The FAA estimates that 796 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish the proposed inspection, at an average labor rate of $60 per work hour. Based on the figures, the cost impact of the inspection proposed by this AD on U.S. operators is estimated to be $47,760, or $60 per airplane.

It would take approximately 16 work hours to accomplish the proposed compliance plan, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the compliance plan proposed by this AD on U.S. operators is estimated to be $960.

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:

Start Authority

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 2000-NM-313-AD.

Applicability: All Model 737-300, -400, and -500 series airplanes, 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 (d) 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 detect and correct chafing and to prevent electrical contact between the fuel quantity indicating system (FQIS) wiring and the surrounding structure, which, in conjunction with another wiring failure outside the fuel tank, could result in fire or explosion of the fuel tank, accomplish the following:

Compliance Plan

(a) Within 15 days after the effective date of this AD, submit a plan to the FAA that identifies a schedule for compliance with paragraph (b) of this AD. This schedule must include, for each of the operator's affected airplanes, the dates and maintenance events (e.g., letter checks) when the required actions will be accomplished. For purposes of this paragraph, “FAA” means the Principal Maintenance Inspector (PMI) for operators that are assigned a PMI, or the cognizant Flight Standards District Office for other operators. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

Inspection and Corrective Actions

(b) Within 6 months after the effective date of this AD, perform a one-time detailed visual inspection of the FQIS wiring and fuel tubing on the inboard side of the right wing rib wing buttock line (WBL) 227 and on the aft side of stringer No. 13 to determine if a 3/8-inch clearance exists between the FQIS wire harness and the refuel tube and tube coupling, and to detect any loose or broken refuel tube clamp or bracket or chafing of the FQIS wire harness, in accordance with Boeing Alert Service Bulletin 737-28A1168, dated September 26, 2000.

Note 2:

For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, Start Printed Page 58968magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

(1) If the clearance between the FQIS wire harness and the refuel tube is less than 3/8-inch, prior to further flight, readjust the refuel tube, and relocate the bonding jumper away from the wiring, if necessary, in accordance with the service bulletin.

(2) If any loose or broken refuel tube clamp or bracket is found, prior to further flight, replace the broken clamp with a new clamp; repair the broken bracket or replace the broken bracket with a new bracket; and secure the loose clamp or bracket; as applicable; in accordance with the service bulletin.

(3) If any chafing of the FQIS wiring harness is found, prior to further flight, replace the wire harness with a new wire harness or accomplish the applicable action(s) specified in paragraph (b)(3)(i), (b)(3)(ii), or (b)(3)(iii) of this AD, in accordance with the service bulletin.

(i) For jacket damage only that is less than 1-inch in length with no sign of abrasion to the wire insulation: Install a teflon sleeve over the wiring. At the next scheduled “C” Check, but no later than 15 months after the effective of this AD, repair the wire harness or replace the wire harness with a new wire harness.

(ii) For jacket damage or a harness with an exposed shield or conductor and the insulation of the other wire is not damaged (there can be no broken shield strands if the shield wire is damaged or no broken wire strands if the unshielded wire is damaged): Install a teflon sleeve over the wiring terminal and along the wire to the damaged area.

(iii) For wire harness damage to the wire shield of the shielded wire or to the conductor of the unshielded wire: Splice the wires and install a teflon sleeve over the splice.

Reporting Requirement

(c) Submit a report of inspection findings to Service Bulletin Engineering, Boeing Commercial Airplane Group, P.O. Box 3707, Mail Stop 2H-37, Seattle, Washington 98124-2207; at the applicable time specified in paragraph (c)(1) or (c)(2) of this AD. The report must include all the information specified in paragraph K. of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-28A1168, dated September 26, 2000. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

(1) For airplanes on which the inspection required by paragraph (b) of this AD is accomplished after the effective date of this AD: Submit the report within 10 days after performing the inspection.

(2) For airplanes on which the inspection required by paragraph (b) of this AD has been accomplished prior to the effective date of this AD: Submit the report within 10 days after the effective date of this AD.

Alternative Methods of Compliance

(d) 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. Operators shall submit their requests through an appropriate FAA PMI, 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 Permits

(e) 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.

Start Signature

Issued in Renton, Washington, on September 26, 2000.

John J. Hickey,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 00-25327 Filed 10-2-00; 8:45 am]

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