00-30320. Airworthiness Directives; Boeing Model 707 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 series airplanes. This proposal would require modification of certain areas of the upper skin of the wing. This action is necessary to prevent cracking of the upper skin of the wing, which could result in reduced structural integrity of the wing. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by January 12, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-279-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 [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-279-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:

James Rehrl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

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-279-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-279-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that cracking has been detected in the upper skin of the wing at wing stringers 10A and 11A on both the left- and right-hand wings of certain Boeing Model 707 series airplanes. The cracking has been attributed to skin fatigue. This condition, if not corrected, could result in reduced structural integrity of the wing.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 2378, Revision 1, dated June 30, 1967, which, among other actions, describes procedures for modification of the upper skin of the wing at wing stringers 10A and 11A. The modification involves removing fasteners at the inboard and outboard ends of the stringer, inspecting these fastener holes using an eddy current method to detect cracking, counterboring the inner surface of the stringer at each fastener hole, installing an anti-fretting strip between the wing and stringer, enlarging fastener holes to remove fatigued metal, and installing new, improved fasteners. 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 modification specified in the service bulletin described previously, except as discussed below.

Differences Between the Proposed Rule and Service Bulletin

Operators should note that the service bulletin recommends, and describes procedures for, an initial ultrasonic inspection of the wing upper skin prior to the accumulation of 18,000 flight hours or within 800 flight hours after receipt of the service bulletin, whichever occurs later. The service bulletin also recommends repetitive inspections at intervals not to exceed 1,600 flight hours, until accomplishment of a repair or modification. The service bulletin suggests accomplishment of the modification described previously “at the major overhaul closest to 20,000 flight hours.”

This proposed AD would not require the repetitive inspections specified in the service bulletin but would require the modification of the upper skin of the wing at wing stringers 10A and 11A prior to the accumulation of 20,000 flight hours or within 24 months after the effective date of this AD, whichever occurs later. Mandating the terminating action is based on the FAA's determination that long-term continued operational safety will be better assured 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 assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous continual inspections, has led the FAA to consider placing less emphasis on inspections and more emphasis on design improvements. The proposed modification requirement is consistent with these conditions. Also, because many of the airplanes that are affected by this AD will have already passed the compliance threshold of 20,000 flight hours, as suggested in the service bulletin, the FAA finds that it is appropriate to include a grace period of 24 months after the effective date of this AD, to allow time for the modification to be accomplished on all affected airplanes in a timely manner.

Operators also should note that, as explained previously, the procedures for the modification include an HFEC inspection of fastener holes “to ensure that there are no cracks.” However, the service bulletin does not include instructions for corrective actions if a crack is found during this inspection. Therefore, paragraph (b) of this AD states that, if any crack is found during the inspection that is included as part of the modification, the cracks must be repaired in accordance with the applicable chapter of the Boeing 707 Structural Repair Manual.

Cost Impact

There are approximately 5 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1 airplane of U.S. registry would be affected by this proposed AD, that it would take approximately 8 work hours to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on the single U.S. operator is estimated to be $480.

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

[Amended]

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

Boeing: Docket 2000-NM-279-AD.

Applicability: Model 707 series airplanes; as listed in Boeing Service Bulletin 2378, Revision 1, dated June 30, 1967; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent cracking of the upper skin of the wing, which could result in reduced structural integrity of the wing, accomplish the following:

Modification

(a) Prior to the accumulation of 20,000 total flight hours, or within 24 months after the effective date of this AD, whichever occurs later, modify the upper skin of the wing at wing stringers 10A and 11A on both the left-and right-hand wings of the airplane, in accordance with Boeing Service Bulletin 2378, Revision 1, dated June 30, 1967.

(b) During the high frequency eddy current inspection included as part of the modification required by paragraph (a) of this AD, if any crack is found, prior to further flight, repair in accordance with the applicable section of the Boeing 707 Structural Repair Manual.

Alternative Methods of Compliance

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on November 21, 2000.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.