01-17604. Airworthiness Directives; Boeing Model 747-100, 747-200B, 747-200C, 747-200F, 747SP, and 747SR 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 747-100, 747-200B, 747-200C, 747-200F, 747SP, and 747SR series airplanes. This proposal would require a one-time inspection for chafing of certain wire bundles behind the flight engineer's panel; repairs, if necessary; and a modification to reroute a certain electrical wire bundle to ensure sufficient clearance between that wire bundle and an adjacent flood light support bracket. This action is necessary to prevent chafing of certain electrical wire bundles, which could result in smoke in the cockpit, and uncommanded discharge of fire extinguishing bottles for the No. 4 engine and consequent reduction of the ability to fight a fire in the No. 4 engine. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by September 6, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-220-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 [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. 2001-NM-220-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:

Stephen Oshiro, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-220-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-220-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Background

In July 1996, a Boeing Model 747 series airplane was involved in an accident. As part of re-examining all aspects of the service experience of the airplane involved in the accident, the FAA participated in design review and testing to determine possible sources of ignition in center fuel tanks. As part of the review, we examined fuel system wiring with regard to the possible effects that wire degradation may have on arc propagation.

In 1997 in a parallel preceding, at the recommendation of the White House Commission on Aviation Safety and Security, the FAA expanded its Aging Transport Program to include non-structural systems and assembled a team for evaluating these systems. This team performed visual inspections of certain transport category airplanes for which 20 years or more had passed since date of manufacture. In addition, the team gathered information from interviews with FAA Principal Maintenance Inspectors and meetings with representatives of airplane manufacturers. This evaluation revealed that the length of time in service is not the only cause of wire degradation; inadequate maintenance, contamination, improper repair, and mechanical damage are all contributing factors. From the compilation of this comprehensive information, we developed the Aging Transport Non-Structural Systems Plan to increase airplane safety by increasing knowledge of how non-structural systems degrade and how causes of degradation can be reduced.

In 1998, an accident occurred off the coast of Nova Scotia involving a McDonnell Douglas Model MD-11 series airplane. Investigation indicates that a fire broke out in the cockpit and first class overhead area. Although the ignition source of the fire has not been determined, the FAA, in conjunction with Boeing and operators of Model MD-11, DC-8, DC-9, DC-10, and DC-9-80 series airplanes, is reviewing all aspects of the service history of those airplanes to identify potential unsafe conditions associated with wire degradation due to various contributing factors (e.g., inadequate maintenance, contamination, improper repair, and mechanical damage) and to take appropriate corrective actions. We have issued a series of airworthiness directives (AD) that address unsafe conditions identified during that process. This process is continuing and we may consider additional rulemaking actions as further results of the review become available. The cause of the Nova Scotia MD-11 accident has not yet been determined.

In 1999, the FAA Administrator established a formal advisory committee to facilitate the implementation of the Aging Transport Non-Structural Systems Plan. This committee, the Aging Transport Systems Rulemaking Advisory Committee (ATSRAC), is made up of representatives of airplane manufacturers, operators, user groups, aerospace and industry associations, and government agencies. As part of its mandate, ATSRAC will recommend rulemaking to increase transport category airplane safety in cases where solutions to safety problems connected to aging systems have been found and must be applied. Detailed analyses of certain transport category airplanes that have been removed from service, studies of service bulletins pertaining to certain wiring systems, and reviews of previously issued ADs requiring repetitive inspections of certain wiring systems, have resulted in valuable information on the cause and prevention of wire degradation due to various contributing factors (e.g., inadequate maintenance, contamination, improper repair, and mechanical damage).

In summary, as a result of the investigations described above, the FAA has determined that corrective action may be necessary to minimize the potential hazards associated with wire degradation and related causal factors (e.g., inadequate maintenance, contamination, improper repair, and mechanical damage).

Identification of Unsafe Condition

The FAA has received a report that, during landing of a certain Model 747 series airplane, smoke emanated from the forward edge of the flight engineer's panel in the cockpit. The flight crew responded to the situation by immediately switching off galley power and undertaking smoke evacuation procedures. Investigation following landing revealed that a small section of electrical wire bundle W530, which was routed behind the flight engineer's panel, had chafed against a flood light support bracket and burned. The consequent short circuit caused several circuit breakers to open and both fire extinguisher bottles for No. 4 engine to discharge. This condition, if not corrected, could result in smoke in the cockpit. Also, if the fire extinguisher bottles for the No. 4 engine are inadvertently discharged, it could result in reduced ability to fight a fire in that engine.

Other Related Rulemaking

This proposed AD is one of a series of actions identified as part of the ATSRAC program initiative to maintain continued operational safety of aging non-structural systems in transport category airplanes. The program is continuing and the FAA may consider additional rulemaking actions as further results of the review become available.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin 747-25A2407, Revision 1, dated September 23, 1999, which describes procedures for a modification to reroute electrical wire bundle W530 to ensure sufficient clearance between that wire bundle and an adjacent flood light support bracket. The modification relocates one existing wire bundle clamp farther away from the flood light support bracket and installs a caterpillar grommet on the flood light supports. 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 a one-time detailed visual inspection for chafing of certain wire bundles behind the flight engineer's panel, and repair, if necessary. The proposed AD also would require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

Differences Between Proposed AD and Service Bulletin

This proposed AD differs from the service bulletin in the following ways:

• The service bulletin does not contain procedures for the detailed visual inspection for chafing of certain wire bundles or for repair if any chafing is found, which would be required by the proposed AD. However, in view of the unsafe condition (chafing of electrical wire bundles, which could result in smoke in the cockpit), the FAA finds it necessary to propose to require such an inspection, and repairs, if necessary, to ensure that any chafed wire bundle is found and fixed in a timely manner. Therefore, this action proposes to require these actions before accomplishment of the modification described in the service bulletin. Also, Note 2 of this proposed rule defines what we mean by “detailed visual inspection.” We find that this proposed inspection requirement would not substantially increase the number of work hours necessary to accomplish this proposed AD over the time necessary for the modification described in the service bulletin. No additional access over that necessary for the modification is involved, the inspection area is small, and the number of wire bundles is few. Thus, the FAA has used the figure of 12 work hours provided in the service bulletin for the cost impact estimate in this proposed AD.
• The service bulletin recommends that the actions be accomplished “at the earliest opportunity when manpower and facilities are available.” The FAA finds 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 the degree of urgency associated with addressing the subject unsafe condition. In light of all relevant factors, we find a compliance time of 12 months after the effective date of the AD for completing the proposed actions is warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.
• The service bulletin specifies that installation of the caterpillar grommet on the flood light supports may be done according to a certain chapter of the Boeing 747 Overhaul Manual (OHM) or “your equivalent procedure.” However, this proposed AD would require that the installation of the caterpillar grommet be accomplished per the referenced chapter of the OHM. An “equivalent procedure” may be used only if approved as an alternative method of compliance under paragraph (c) of this proposed AD.

Cost Impact

There are approximately 217 airplanes of the affected design in the worldwide fleet. The FAA estimates that 108 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 12 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. The cost of required parts per airplane would be negligible. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $77,760, or $720 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.

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 2001-NM-220-AD.

Applicability: Model 747-100, 747-200B, 747-200C, 747-200F, 747SP, and 747SR series airplanes; as listed in Boeing Alert Service Bulletin 747-25A2407, Revision 1, dated September 23, 1999; 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 prevent chafing of certain electrical wire bundles located behind the flight engineer's panel, which could result in smoke in the cockpit, and uncommanded discharge of fire extinguishing bottles for the No. 4 engine and consequent reduction of the ability to fight a fire in the No. 4 engine, accomplish the following:

One-Time Inspection and Modification

(a) Within 12 months after the effective date of this AD, perform a one-time detailed visual inspection for chafing of wire bundles in the area of the forward upper corner of the P4 flight engineer's panel, outboard of the drip shield. Pay particular attention to wire bundles W528 and W530.

(1) If any chafing is found, before further flight, repair the chafed wire bundles according to Section 20-10-13 of the Boeing Standard Wiring Practices Manual, and do paragraph (a)(2) of this AD.

(2) If no chafing is found, or after chafing has been repaired, before further flight, modify the airplane by rerouting electrical wire bundle W530 to ensure sufficient clearance between that wire bundle and an adjacent flood light support bracket and installing a caterpillar grommet on the flood light supports, according to Boeing Alert Service Bulletin 747-25A2407, Revision 1, dated September 23, 1999.

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

Operator's Equivalent Procedure

(b) Where Boeing Alert Service Bulletin 747-25A2407, Revision 1, dated September 23, 1999, specifies that installation of a caterpillar grommet may be accomplished per “your equivalent procedure,” the procedures must be accomplished per the applicable chapter of the Boeing 747 Overhaul Manual specified in the service bulletin.

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 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

(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 July 9, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.