Airworthiness Directives; Boeing Model 767 Series Airplanes Powered by Pratt & Whitney Model PW4000 Series Engines

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 767 series airplanes. This proposal would require a one-time detailed visual inspection of certain wire bundles located in the aft section of the strut forward fairing panel of both engine struts to detect chafing damage, and repair or replacement of wiring, if necessary. This action is necessary to prevent the potential for dual wire faults from grounded, separated, or shorted wires; which could result in inadvertent takeoff thrust overboost, in-flight loss of thrust, or engine shutdown.

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-19-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-19-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:

Dennis Kammers, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2956; fax (425) 227-1181.

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-19-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-19-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating several incidents of severe chafing of certain wire bundles in both engine struts on Model 767 series airplanes powered by Pratt & Whitney PW4000 series engines. One incident resulted in damage to the shielding of multiple wires. The subject wire bundles contain wires associated with the following engine systems: electronic control, fire/overheat detection, starter air valve, airborne vibration monitoring, inlet probe heat, and fuel shutoff valve. The affected wires are routed through two clamps attached to a hydraulic pressure line, and the chafing may be caused by a high-frequency pump ripple transmitted from the engine-driven hydraulic pump. This chafing could potentially lead to dual wire faults from grounded, separated, or shorted wires; which could result in inadvertent takeoff thrust overboost, in-flight loss of thrust, or in-flight engine shutdown.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 767-73A0049, Revision 2, dated April 27, 2000, which describes procedures for a one-time detailed visual inspection of certain wire bundles located in the aft section of the strut forward fairing panel of both engine struts to detect chafing damage, and repair or replacement of damaged wire bundles. The service bulletin also contains instructions for submitting a report of the inspection results to the manufacturer.

The service bulletin references Boeing Standard Wiring Practices Manual for accomplishment of the repair of fire detection or overheat system wires.

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.

Differences Between Service Bulletin and Proposed Rule

Operators should note that, although the effectivity listing in the service bulletin specifies “all PW4000 powered 767 airplanes line numbers 0001 through 0778,” the applicability statement of this AD specifies “Model 767 series airplanes powered by Pratt & Whitney Model PW4000 series engines.” The FAA has determined that it is necessary to include line numbers 0779 and subsequent in the applicability of this AD because those additional airplanes are subject to the same unsafe condition as the airplanes specified in the service bulletin.

Operators also should note that Section 3.B.1.a.(3) of the Accomplishment Instructions of the service bulletin describes instructions for repairing fire detection or overheat system wires in accordance with Boeing Standard Wiring Practices Manual, Subject 20-10-13, Section 2. The FAA has determined that Section 2 of Subject 20-10-13 does not provide the special instructions for repair of fire detection or overheat system wires. These repairs should be accomplished in accordance with Subject 20-10-13, Section 4B, of Boeing Standard Wiring Practices Manual. This section describes the assembly of splices with fire detection or overheat system wires.

Interim Action

This is considered to be interim action. The inspection reports that are required by this AD will enable the manufacturer to obtain better insight into the nature, cause, and extent of the chafing, and eventually to develop final action to address the unsafe condition. Once final action has been identified, the FAA may consider further rulemaking.

Cost Impact

There are approximately 147 airplanes of the affected design in the worldwide fleet. The FAA estimates that 61 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 2 work hours per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspection proposed by this AD on U.S. operators is estimated to be $7,320, or $120 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.