Airworthiness Directives; Boeing Model 777-200 and -300 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 777-200 and -300 series airplanes. This proposal would require modification of the bolt holes of the lower side of the body splice t-chord common to the paddle fitting of the lower wing panel. The modification includes performing a high frequency eddy current inspection of the fastener hole for cracks, repairing the hole if necessary, and replacing the fasteners with new inconel bolts. This action is necessary to prevent fatigue cracks in the lower t-chord at the bolt holes common to the paddle fittings that could result in fractures of one or more of the t-chord segments, which could lead to detachment of the lower wing panel and consequent loss of the wing. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by August 2, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2003-NM-214-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. 2003-NM-214-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 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplanes, 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:

Gary Oltman, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6443; fax (425) 917-6590

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 2003-NM-214-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. 2003-NM-214-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report indicating that, during full scale fatigue testing of a Boeing Model 777 series airplane, fatigue cracks were found in the lower side of the body splice t-chord common to the paddle fitting bolt holes. Fatigue cracks were found on both sides of the airplane between stringers 1 and 14. This condition, if not prevented, could result in fractures of one or more of the t-chord segments, which could lead to detachment of the lower wing panel and consequent loss of the wing.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 777-57A0040, Revision 1, dated July 10, 2003, which describes procedures for performing repetitive ultrasonic and high frequency eddy current (HFEC) inspections of the t-chord for cracks, and modification of the lower paddle fitting fasteners. The modification includes performing a high frequency eddy current inspection of the fastener hole for cracks, repairing the hole if necessary, and replacing the fasteners with new inconel bolts. The service bulletin also specifies contacting the manufacturer for certain repair conditions. Accomplishment of the modification ends the repetitive inspections.

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 rule would require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

Operators should note that the service bulletin specifies doing repetitive ultrasonic and HFEC inspections until the modification is accomplished. However, this proposal only specifies performing the modification of the bolt holes of the lower side of the body splice t-chord common to the paddle fitting of the lower wing panel (includes replacing the fasteners with new inconel bolts, performing an HFEC inspection of the fastener hole for cracks, and repairing the hole as applicable). We can better ensure long-term continued operational safety by modifications or design changes to remove the source of the problem, rather than by repetitive inspections. Long-term inspections may not provide the degree of safety necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous repetitive inspections, has led us to consider placing less emphasis on special procedures and more emphasis on design improvements. We also considered that the work hours needed to do the inspections in Part 1 of the service bulletin are comparable to the work hours needed to do the modification in Part 2 of the service bulletin. We were informed that most likely the inspections would be skipped and only the modification would be accomplished. In consideration of all of these factors, we determined that performing the modification best addresses the unsafe condition, while still maintaining an adequate level of safety.

Operators should also note that, although the service bulletin specifies that the manufacturer may be contacted for additional instructions for repair of certain cracks, this proposal would require the repair to be accomplished per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.

Cost Impact

There are approximately 262 airplanes of the affected design in the worldwide fleet. The FAA estimates that 73 airplanes of U.S. registry would be affected by this proposed rule, that it would take approximately 34 work hours per airplane to accomplish the proposed modification, and that the average labor rate is $65 per work hour. Required parts would cost between approximately $21,686 and $24,803 per airplane. Based on these figures, the cost impact of the proposed rule on U.S. operators is estimated to be between $1,744,408 and $1,971, 949, or between $23,896 and $27,013 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.