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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-378-AD; Amendment 39-12027; AD 2000-24-20] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Final rule. 

# SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to all Boeing Model 707 and 720 series airplanes, that requires repetitive inspections of certain stringers and around certain fastener holes of the lower skin of the wings to detect fatigue cracking, and repair, if necessary. This action is necessary to detect and correct such cracking and consequent damage to adjacent structure, which could result in reduced structural integrity of the airplane. This action is intended to address the identified unsafe condition. 

# DATES:

Effective January 8, 2001. 

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of January 8, 2001. 

# ADDRESSES:

The service information referenced in this AD may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

# 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 (425) 227-2783; fax (425) 227-1181. 

# SUPPLEMENTARY INFORMATION:

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to all Boeing Model 707 and 720 series airplanes was published in the                     **Federal Register**                     on August 10, 2000 (65 FR 48941). That action proposed to require repetitive inspections of certain stringers and around certain fastener holes of the lower skin of the wings to detect fatigue cracking, and repair, if necessary.                 

## Comment Received 

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received. 

The commenter, Boeing, requests that all references to Model 720 series airplanes be deleted from the proposed rule. Specifically, Boeing suggests that: 
    - the Cost Impact paragraph be revised to specify that there are approximately “* * * 49 affected Model 707 series airplanes worldwide * * *;”
    - paragraph (a) of the proposed rule be removed; and
    - Note 2 of the proposed rule be revised to state that the actions required by AD 81-11-06 R1, amendment 39-4178, for Model 720 airplanes remain in effect. The commenter states that there are no Model 720 series airplanes in active service. In addition, the changes in Revision 4 of the referenced alert service bulletin affect only Model 707 series airplanes.

The FAA does not concur with the commenter's request to remove references to Model 720 series airplanes from this final rule. Even though no Model 720 series airplanes are currently in active service, including this model in the applicability of the final rule is necessary to ensure that the unsafe condition is addressed on any Model 720 series airplane that is returned to service in the future. In addition, the FAA notes that several changes in Revision 4 of the alert service bulletin do, in fact, address Model 720 series airplanes. No change to this final rule is necessary. 

## Conclusion 

After careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed. 

## Cost Impact 

There are approximately 49 Model 707 and 720 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 2 airplanes of U.S. registry will be affected by this AD, that it will take approximately 56 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $6,720, or $3,360 per airplane, per inspection cycle. 

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the 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 adopted herein will 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                           ( print page 75589)                        levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.                 

                    For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption                     **ADDRESSES.**

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Incorporation by reference
      - Safety

## Adoption of the Amendment 

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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: 

**2000-24-20 Boeing:**                             Amendment 39-12027. Docket 99-NM-378-AD.                         

*Applicability:*                             All Model 707 and 720 series airplanes, 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 (e) 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 detect fatigue cracking of certain stringers, and around certain fastener holes of the lower skin of the wings, which could result in damage to adjacent structure and consequent reduced structural integrity of the airplane, accomplish the following: 

## Initial and Repetitive Inspections 

(a) For Model 720 series airplanes: Within 500 flight cycles after the effective date of this AD, perform an initial high frequency eddy current (HFEC) inspection to detect cracking, in accordance with Figure 1 of Boeing Alert Service Bulletin A3395, Revision 4, dated October 28, 1999. 

(b) For Model 707 series airplanes having fewer than 15,000 total flight cycles as of the effective date of this AD: Prior to the accumulation of 15,000 total flight cycles, or within 150 flight cycles after the effective date of this AD, whichever occurs later, perform an initial HFEC inspection in accordance with Figure 2; steps 1, 2, and 3; of Boeing Alert Service Bulletin A3395, Revision 4, dated October 28, 1999. Repeat the inspection thereafter at intervals not to exceed 1,300 flight cycles. Accomplishment of the repetitive HFEC inspections terminates the low frequency eddy current inspections specified in AD 81-11-06 R1, amendment 39-4178. 

(c) For Model 707 series airplanes having 15,000 total flight cycles or more as of the effective date of this AD: Within 150 flight cycles after the effective date of this AD, perform an initial HFEC inspection in accordance with Figure 2; steps 4, 5, and 6; of Boeing Alert Service Bulletin A3395, Revision 4, dated October 28, 1999, and accomplish the requirements in paragraphs (c)(1) and (c)(2) of this AD. 

(1) Repeat the inspection thereafter at intervals not to exceed 150 flight cycles until accomplishment of the inspections required by paragraph (c)(2) of this AD. 

(2) Within 400 flight cycles after accomplishment of the initial inspection required by paragraph (c) of this AD, accomplish the HFEC inspections required by paragraph (b) of this AD. Accomplishment of these inspections terminates the repetitive inspections required by paragraph (c)(1) of this AD. 

# Note 2:

The actions required by AD 81-11-06 R1, amendment 39-4178 [with the exception of the LFEC inspections, as specified in paragraph (b) of this AD] remain in effect.

## Inspect and Repair 

(d) If any cracking is detected during any inspection required by this AD, prior to further flight, perform an internal inspection in accordance with the Work Instructions specified in Boeing Alert Service Bulletin A3395, Revision 4, dated October 28, 1999; and, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with 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 method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. 

## Alternative Methods of Compliance 

(e) 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 ACO. 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 3:

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

## Special Flight Permit 

(f) 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. 

## Incorporation by Reference 

(g) Except as required by paragraph (d) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin A3395, Revision 4, dated October 28, 1999. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

## Effective Date 

(h) This amendment becomes effective on January 8, 2001. 

Issued in Renton, Washington, on November 22, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-30397 Filed 12-1-00; 8:45 am] 

BILLING CODE 4910-13-P