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

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that would have required 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 new action revises the proposed rule by adding replacement of wires repaired by splicing and damaged wires that require splicing, and replacement of the support brackets of the existing wire bundles with new brackets and clamps, which would terminate the existing requirements. The actions specified by this new proposed AD are intended 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 July 2, 2001.

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 a.m. and 3 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 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-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

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on September 18, 2000 (65 FR 56264). That NPRM would have required 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. That NPRM was prompted by reports indicating several incidents of severe wire chafing of certain wire bundles in both engine struts. That condition, if not corrected, could result in the potential for dual wire faults from grounded, separated, or shorted wires; and consequent inadvertent takeoff thrust overboost, in-flight loss of thrust, or engine shutdown.

Actions Since Issuance of Notice of Proposed Rulemaking (NPRM)

Since issuance of the NPRM, the FAA has reviewed and approved Boeing Service Bulletin 767-73A0049, Revision 3, dated December 20, 2000, which contained certain changes from Revision 2 of the service bulletin (referenced as the appropriate source of service information for accomplishment of the actions specified in the proposed rule). Revision 3 adds airplanes that have been manufactured since the issuance of the NPRM; updates warranty information; corrects a wire part number, and clarifies repair/splice instructions for fire zone wiring. Revision 3 has been added as a revised source of service information for accomplishment of the specified actions, and the references to Revision 2 have been removed from the supplemental NPRM. Additionally, paragraph (a)(2) of the NPRM has been revised. The reference to the repair of the wires as specified in the wiring practices manual has been removed from paragraph (a)(2) because Revision 3 corrects the errors contained in Revision 2 describing repair/splice instructions for wires installed in the fire zone. Paragraph (a)(3) has been changed to a new (b)(1), which specifies the replacement of any wires that are damaged and require a splice repair.

The FAA also has reviewed and approved Boeing Service Bulletin 767-73A0049, Revision 4, dated April 5, 2001. Revision 4 is essentially the same as Revision 3 (above), but eliminates one airplane that was inadvertently included in the effectivity section of Revision 3. Revision 4 has been added to the supplemental NPRM as an additional source of service information for accomplishment of the specified actions.

Comments

Due consideration has been given to the comments received in response to the NPRM. Certain comments have resulted in changes to the NPRM.

Terminating Action

One commenter asks that Boeing Service Bulletin 767-73-0051, dated December 20, 2000, replace Boeing Service Bulletin 767-73A0049, which was referenced as the appropriate source of service information for accomplishment of the actions specified in the NPRM. The commenter states that the new service bulletin would provide final corrective action for the unsafe condition, and would eliminate the need for further rulemaking. Another commenter states that the action specified in the NPRM was interim action and asks that the manufacturer's final action be included in the supplemental NPRM.

The FAA partially concurs with the commenters. Since the issuance of the NPRM, the FAA has reviewed and approved Boeing Service Bulletin 767-73-0051. The service bulletin describes procedures for replacement of the support brackets of the existing wire bundle with a new bridge bracket, support bracket, and wire bundle clamps. Accomplishment of the replacement eliminates the need for the inspection and corrective action required by the NPRM, and as the final action, addresses the unsafe condition. Additionally, the applicability in the NPRM has been changed to the same effectivity listed in the service bulletin, because airplanes having line number 822 and after have been delivered with the new bracket installed. A new paragraph (b) has been added to include the replacement as terminating action, and a spares paragraph has been added to ensure that existing parts are not used for the replacement. However, the new service bulletin (above) will not replace the service bulletin referenced in the NPRM because the existing actions will continue to be required until accomplishment of the terminating action.

Conclusion

Since these changes expand the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Differences Between Service Bulletin and Proposed Rule

Boeing Service Bulletin 767-73-0049 recommends that damaged wires repaired by splicing, as specified in paragraph (a)(2) of the NPRM, be replaced at the next scheduled strut system maintenance check. This supplemental NPRM would require that any wires repaired by splicing, and any damaged wires that need to be spliced, be replaced concurrent with the incorporation of the terminating action specified in Boeing Service Bulletin 767-73-0051.

Although Boeing Service Bulletin 767-73-0051 recommends doing the replacement at the next convenient opportunity where facilities and manpower are available, the FAA has determined that this compliance time may not ensure that the identified unsafe condition is addressed in a timely manner. 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, the average utilization of the affected fleet, and the time necessary to perform the proposed AD. In light of all of these factors, the FAA finds a compliance time of within 6,000 flight hours or 18 months after the effective date of this AD, whichever occurs later, to be 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 185 airplanes of the affected design in the worldwide fleet. The FAA estimates that 79 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 2 work hours per airplane to accomplish the proposed inspection, at an average labor rate of $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 $9,480, or $120 per airplane.

It would take approximately 3 work hours per airplane to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $1,570 per airplane. Based on these figures, the cost impact of the replacement proposed by this AD on U.S. operators is estimated to be $138,250, or $1,750 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 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.