Airworthiness Directives; Boeing Model 707 and 720 Series Airplanes

Summary:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 707 and 720 series airplanes. This proposal would require an inspection of the main landing gear (MLG) lock support fitting and the wing fillet flap support link for damage, and corrective action, if necessary; and replacement of the bolts and bushings at the joint between the MLG lock support fitting and the wing fillet flap support link. This action is necessary to prevent stress corrosion cracking of the bolts and wearing of the joint between the lock support fitting and the support link, which could lead to failure of the joint and could cause the collapse of the MLG. This action is intended to address the identified unsafe condition.

Table of Contents

Dates:

Comments must be received by March 29, 2004.

Addresses:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2003-NM-44-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-44-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:

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 2003-NM-44-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-44-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report that one operator found a corroded and worn bolt and bushings at the joint between the main landing gear (MLG) lock support fitting and the wing fillet flap support link on a Boeing Model 707-300 series airplane. Stress corrosion cracking of the bolts and wearing of the joint between the lock support fitting and the support link could lead to failure of the joint. This condition, if not corrected, could cause the collapse of the MLG.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing 707 Alert Service Bulletin A3511, dated February 23, 2003, which describes procedures for performing a high frequency eddy current inspection of the MLG lock support fitting and the wing fillet flap support link for damage, and corrective action, if necessary; and replacing bolts and bushings at the joint between the MLG lock support fitting and the wing fillet flap support link with new CRES bolts and Cadmium-plated Al-Ni-Br bushings. The corrective action includes reworking or replacing the MLG lock support fitting and/or the wing fillet flap support link; and contacting Boeing for repair or replacement if damage is beyond rework limits. 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, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

Operators should note that, although Boeing 707 Alert Service Bulletin A3511, dated January 23, 2003, specifies that the manufacturer may be contacted for rework limits, this proposal would require the repair or replacement of the MLG lock support fitting or the wing fillet flap support link 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.

Although Boeing 707 Alert Service Bulletin A3511, dated January 23, 2003, specifies to rework the forward and aft lug bore and faces of the MLG lock support fitting as given in Boeing Service Bulletin 707-2837, the service bulletin does not specify a specific revision level. This proposal would require rework to be accomplished in accordance with Revision 5 of Boeing Service Bulletin 707-2837, dated March 31, 1978.

Clarification of Wording in Service Bulletin

Due to the existence of two different configurations, the service bulletin uses the terms “trailing edge support link” and “wing fillet flap support link” to describe the attachment point to theMLG lock support fitting. For the purposes of this AD the term “support link” is used to simplify the AD.

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, that it would take approximately 14 work hours per airplane to accomplish the proposed replacement and inspection, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $38,220, or $910 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

2. Section 39.13 is amended by adding the following new airworthiness directive:

Boeing: Docket 2003-NM-44-AD.

Applicability: All Model 707 and 720 series airplanes, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent stress corrosion cracking of the bolts and wearing of the joint between the lock support fitting and the support link, which could lead to failure of the joint and could cause the collapse of the main landing gear (MLG), accomplish the following:

Service Bulletin References

(a) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3511, dated January 23, 2003.

Initial Inspection

(b) Within 12 months or 1,000 flight cycles after the effective date of this AD, whichever comes first, perform a high frequency eddy current (HFEC) inspection of the MLG lock support fitting and the support link for cracks and corrosion in accordance with the service bulletin.

Corrective Actions

(c) If any crack or corrosion is found, during the HFEC inspection required by paragraph (b) of this AD, before further flight, rework the lock support fitting or support link, in accordance with the service bulletin, except as specified in paragraphs (c)(1) and (c)(2) of this AD.

(1) If the service bulletin specifies to contact Boeing for rework limits: Before further flight, repair or replace the lock support fitting or support link per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), 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 Manager, Seattle ACO, to make such findings. For a repair/replacement method to be approved, the approval must specifically reference this AD.

(2) Where the service bulletin specifies to rework the forward and aft lug bore and faces common to the lock support fitting of the MLG as given in Boeing Service Bulletin 707-2837, this AD requires rework to be accomplished only in accordance with Revision 5 of Boeing Service Bulletin 707-2837, dated March 31, 1978.

Replacement of Bolts and Bushings

(d) Within 12 months or 1,000 flight cycles after the effective date of this AD, whichever comes first, replace the bolts and bushings at the joint between the lock support fitting for the MLG and the wing fillet flap with new CRES bolts and Cadmium-plated Al-Ni-Br bushings in accordance with the service bulletin.

Parts Installation

(e) As of the effective date of this AD, no person shall install a bolt, part number BACB30LU10D* or NAS590-*, at the joint between the MLG lock support fitting and the support link, on any airplane.

Alternative Methods of Compliance

(f) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, FAA, is authorized to approve alternative methods of compliance for this AD.

Issued in Renton, Washington, on February 5, 2004. Kevin M. Mullin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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