01-7737. Airworthiness Directives; Boeing Model 707 and 720 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 707 and 720 series airplanes. This proposal would require replacement of wiring for the fuel boost pumps and override pumps with new wiring, installation of Teflon sleeving on the wiring, and associated actions. This proposal also would require repetitive inspections to detect damage of the wiring or evidence of a fuel leak. This action is necessary to detect and correct damaged wiring for the fuel boost pumps and override pumps, which could cause electrical arcing that could puncture the conduit containing the wire, and result in an explosion or fire adjacent to the fuel tank. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by May 14, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-318-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 [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. 2000-NM-318-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:

Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

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 2000-NM-318-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-318-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report that, while investigating a fuel leak around the bolts on the number 1 fuel boost pump on a Boeing Model 707 series airplane, an operator found wire damage where the fuel boost pump wiring exited the boost pump and entered the boost pump access area. (The damage is generated by movement of the wire against an adjacent surface, which is due to normal vibrations of the airplane.) Electrical wiring for the fuel boost pump is contained inside a metallic conduit installed in the fuel tank. Damaged wiring for the fuel boost pumps, if not corrected, could cause electrical arcing that could puncture the conduit containing the wiring, and result in an explosion or fire adjacent to the fuel tank. The installation of wiring for the fuel override pumps is similar; thus, wiring for the fuel override pumps could also be subject to the same unsafe condition.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin A3500, dated July 27, 2000, which describes procedures for replacement of wiring for the fuel boost pumps and override pumps, and associated actions. The associated actions described in the service bulletin include the following:

• Inspecting the area of the fuel boost pumps and override pumps to find evidence of a fuel leak, and locating the source of any fuel leak detected in that area;
• Removing the wiring of the fuel boost pumps and override pumps and inspecting it for damage, such as evidence of electrical arcing or exposed copper wire, or evidence of a fuel leak;
• Replacing the conduit where any electrical arcing or fuel leakage has occurred;
• Installing new wiring for each fuel boost pump and override pump; and
• Installing Teflon sleeving over the new wiring.

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.

The proposed AD would also require repetitive detailed visual inspections for damage (e.g., evidence of electrical arcing or exposed copper wire) of the fuel boost pump and override pump wiring or evidence of a fuel leak at least every 30,000 flight hours after replacement of the wiring. The FAA based the decision to propose these repetitive inspections on several factors, including the degree of urgency associated with this unsafe condition. In view of the considerations associated with wiring of the fuel boost pumps and override pumps, the FAA finds it necessary to propose repetitive inspections.

Explanation of Compliance Time

This proposed AD would require accomplishment of the initial inspection and replacement of wiring within 1 year or 4,000 flight hours after the effective date of the AD, whichever occurs first. In developing an appropriate compliance time for this proposed AD, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition and the average utilization of the affected fleet. In light of all of these factors, the FAA finds this compliance time 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 261 airplanes of the affected design in the worldwide fleet. The FAA estimates that 65 airplanes of U.S. registry would be affected by this proposed AD.

The proposed replacement and initial associated actions would take approximately 27 work hours per airplane, at the average labor rate of $60 per work hour. Based on these figures, the FAA estimates the cost impact of these proposed actions on U.S. operators to be $105,300, or $1,620 per airplane.

The inspection for damage of the wiring or evidence of a fuel leak would take approximately 3 work hours per airplane, at the average labor rate of $60 per work hour. Based on these figures, the FAA estimates the cost impact of this inspection on U.S. operators to be $11,700, or $180 per airplane, per inspection cycle.

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.

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:

Boeing: Docket 2000-NM-318-AD.

Applicability: Model 707 and 720 series airplanes, line numbers 1 through 941 inclusive, 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 detect and correct damaged wiring for the fuel boost pumps and override pumps, which could cause electrical arcing that could puncture the conduit containing the wire and result in an explosion or fire adjacent to the fuel tank, accomplish the following:

Replacement of Wiring, Installation of Sleeving, and Associated Actions

(a) Within 1 year or 4,000 flight hours after the effective date of this AD, whichever occurs first, replace the wiring for the fuel boost pumps and override pumps, install Teflon sleeving over the wiring, and do all associated actions, per the Accomplishment Instructions of Boeing Alert Service Bulletin A3500, dated July 27, 2000. The associated actions include performing a general visual inspection of the area around each fuel boost pump and override pump for evidence of a fuel leak; finding the source of any fuel leak and repairing the affected area; replacing the conduit, if required; and performing a detailed visual inspection of the wiring installed in the conduit for evidence of electrical arcing or a fuel leak, or exposed copper wire. If replacement of the conduit is deferred per the service bulletin, repeat the inspection for fuel leaks every 500 flight hours until the conduit is replaced, and replace the conduit within 6,000 flight hours or 18 months, whichever occurs first.

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 under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, 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.”

Note 3:

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, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Repetitive Inspections

(b) After replacement of the wiring per paragraph (a) of this AD, repeat the detailed visual inspection of the wiring for the fuel boost pumps and override pumps for damage, such as evidence of electrical arcing or exposed copper wire, or evidence of a fuel leak. Repeat the inspection at least every 30,000 flight hours, per the Accomplishment Instructions of Boeing Alert Service Bulletin A3500, dated July 27, 2000. If any discrepancy is detected during any inspection per this paragraph, before further flight, replace the wiring and conduit, and install new Teflon sleeving.

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, Seattle 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, Seattle ACO.

Note 4:

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

(d) Special flight permits may be issued in accordance with §§ 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 March 23, 2001.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.