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 repetitive inspections of the upper and lower barrel nuts and bolts that retain the aft trunnion support fitting of each main landing gear for corrosion, cracks, and loose or missing nuts and bolts; torque checks of the upper and lower bolts to verify the torque is within a specified range; and corrective actions, if necessary. This action is necessary to detect and correct cracking and/or loss of the barrel nuts and bolts that retain the aft trunnion support fitting, which could result in the collapse of the main landing gear upon landing. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by February 2, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-335-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. 2002-NM-335-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 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:

Candice Gerretsen, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6428; 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 2002-NM-335-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. 2002-NM-335-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that one operator found cracks in the barrel nut that attaches the aft trunnion bearing cap of the main landing gear to the trunnion support fitting and that another operator discovered that the barrel nut and bolt were missing, on Boeing Model 707 series airplanes. The cause of the cracking is stress corrosion. This condition, if not detected and corrected, could result in cracking and/or loss of the barrel nuts and bolts that retain the aft trunnion support fitting, which could result in the collapse of the main landing gear upon landing.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing 707/720 Alert Service Bulletin A3509, dated June 13, 2002, which describes procedures for performing repetitive detailed inspections of the upper and lower barrel nuts and bolts that retain the aft trunnion support fitting of each main landing gear for corrosion, cracks, and loose or missing nuts and bolts; torque checks of the upper and lower bolts to verify the torque is within the specified range; and corrective actions, if necessary. The corrective actions consist of performing a detailed inspection of the aft trunnion bearing cap and aft trunnion support fitting for corrosion, and repair if necessary; performing a magnetic particle inspection of the aft trunnion bearing cap for cracks, and replacement if necessary; and reinstalling the main landing gear trunnion with new Inconel barrel nuts and bolts to retain the aft trunnion support fitting. 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.

Cost Impact

There are approximately 230 airplanes of the affected design in the worldwide fleet. The FAA estimates that 42 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish the proposed detailed inspection of the upper and lower barrel nuts and bolts and the torque check. The average labor rate is $65 per work hour. Based on these figures, the cost impact on U.S. operators is estimated to be $2,730, or $65 per airplane, per inspection and torque check.

It would take approximately 3 work hours per airplane to accomplish the proposed detailed inspection of the aft trunnion bearing cap. The average labor rate is $65 per work hour. Based on these figures, the cost impact on U.S. operators is estimated to be $8,190, or $195 per airplane.

It would take approximately 4 work hours per airplane to accomplish the proposed installation of the new Inconel barrel nut and bolt and the main landing gear trunnion. The average labor rate is $65 per work hour. Based on these figures, the cost impact on U.S. operators is estimated to be $10,920, or $260 per airplane.

Required parts would cost approximately $3,380 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 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.