RULES and REGULATIONS DEPARTMENT OF TRANSPORTATION

14 CFR Part 39 Docket No. 84 -NM- 10 -AD; Amdt. 39 -4913 Airworthiness Directives; Boeing Model 747 Series Airplanes

49 FR 36365 Airworthiness Directive 84 - 19 - 01 Monday, September 17, 1984 AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This amendment adds a new airworthiness directive (AD) applicable to certain Boeing Model 747 series airplanes which requires inspection for cracks and repair, as necessary, of the frame to tension tie joints at body station 760 (Group I and II airplanes) or body station 780 (Group III airplanes). This action is prompted by a report of a crack which occurred during fatigue testing. An undetected crack could result in loss of cabin pressurization and extensive structural damage. EFFECTIVE DATE: October 19, 1984. ADDRESSES: The applicable service documents may be obtained upon request from the Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124, or may be examined at the address shown below. FOR FURTHER INFORMATION CONTACT: Mr. Owen Schrader, Airframe Branch, ANM- 120S, FAA, Northwest Mountain Region, Seattle Aircraft Certification Office, 9010 East Marginal Way S outh, Seattle, Washington; telephone (206) 431 -2923. Mailing address: FAA, Northwest Mountain Region, 17900 Pacific Highway South, C - 68966, Seattle, Washington 98168. SUPPLEMENTARY INFORMATION: A proposal to amend Part 39 of the Federal Aviation Regulations to include an AD to require inspection for and repair of cracks in the structure was published in the Federal Register on April 30, 1984 (49 FR 18310). The comment period for the proposal closed on June 15, 1984. Interested persons have been afforded an opportunity to participate in the making of this AD. Due consideration has been given to the one comment which was received from the Air Transport Association of America (ATA). The ATA, on behalf of one operator, requested that the repetitive inspection interval be increased to 3700 landings to be in agreement with the Service Bulletin. The FAA concurs, as the 3000 landing figure wa s an editorial error, and paragraph A. of the AD has been revised accordingly. It is estimated that 72 airplanes of U.S. registry are affected by this AD, that it will take approximately 3 man-hours per airplane to accomplish the required inspection, and that the average labor cost wi ll be $40 per man-hour. Based onthese figures, the total cost impact of the AD is estimated to be $8640. For these reasons, this rule is not considered to

be a major rule under the criteria of Executive Order 12291 , or a significant rule under DOT Regulatory Policies and Procedures. Few, if any, small entities within the meaning of the Regulatory Flexibility Act are affected. After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the proposed rule with the change noted. List of Subjects in 14 CFR Part 39 Aviation safety, Aircraft. Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, § 39.13 of Part 39 of the Federal Aviation Regulations ( 14 CFR 39.13) is amended by adding the following new airworthiness directive: Boeing: Applies to Boeing Model 747 series airplanes, certificated in all categories, listed in Boeing Service Bulletin 747 - 53 -2088, Revision 2, or later FAA approved revisions. To detect cracks and prevent failure of the frame to tension tie joint structure, accom plish the following unless already accomplished: A. For airplanes that have been mo dified in accordance with Service Bulletin 747 - 53 -2088, within the next 500 landings after the effective date of this AD or prior to the accumulation or 8,000 landings, whichever is later, perform a close visual inspection of the tension tie at body station (BS) 760 on Group I and Group II airplanes, and at BS 780 on Group III airplanes, for cracks in the areas identified in Service Bulletin 747 - 53 -2088, Revision 2, or later FAA approved revisions. Repeat inspections at intervals not to exceed 3700 landings. If cracks are found, repair and mo dify in accordance with Service Bulletin 747 - 53 -2088, Revision 2, or later FAA approved revisions, prior to further pressurized flight. Inspections are to continue after repair. B. For airplanes that have been mo dified in accordance with Service Bulletin 747 - 53 -2088, within the next 1000 landings after the effective date of this AD or prior to the accumulation of 10,000 landings after mo dification, whichever is later, perform a close visual inspection of the tension tie at BS 760 on Group I and Group II airplanes, and at BS 780 on Group III airplanes, for cracks in the areas identified for inspection in Service Bulletin 747 - 53 -2088, Revision 2, or later FAA approved revisions. Repeat inspections at intervals not to exceed 8000 landings. If cracks are found, repair in accordance with Service Bulletin 747 - 53 -2088, Revision 2, or later FAA approved revisions, prior to further pressurized flight. Inspections are to continue after repair. C. Alternate means of com pliance with the AD which provide an equivalent level of safety may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. D. For pur

poses of complying with this AD, subject to acceptance by the assigned FAA Maintenance Inspector, the number of landings may be determined by dividing each airplane's time in service by the operator's fleet average time from takeoff to landing for the airp lane type. E. Aircraft may be ferried to a base for maintenance in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations. F. Upon request of

the operator, an FAA Maintenance Inspector, subject to prior approval of the Manager, SeattleAircraft Certification Office, FAA, Northwest Mountain Region, may adjust the inspection times specified in this AD

to permit com

pliance at an established inspection period of an operator, if the request contains substantiating data to justify the adjustment period. This amendment becomes effective October 19, 1984. (Secs. 313(a), 314(a), 601 through 610, and 1102 of the Federal Aviation Act of 1958 (49 U.S.C. 1354(a), 1421 through 1430, and 1502); 49 U.S.C. 106(g) (Revised, Pub. L. 97 -449, January 12, 1983); and 14 CFR 11.89 ) Note.

—For the reasons discussed earlier in the pream ble, the FAA has determined that this regulation is not considered to be major under Executive Order 12291 or significant under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and it is further certified under the criteria of the Regulatory Flexibility Act that this rule will not have a significant economic effect on a substantial num ber of small entities because few, if any, Boeing Model 747 airplanes are operated by small entities. A final evaluation has been prepared for this regulation and has been placed in the docket. A copy of it may be obtained by contacting the person identified under the caption “FOR FURTHER INFORMATION CONTACT.” Issued in Seattle, Washington, on September 4, 1984. Wayne J. Barlow, Acting Director, Northwest Mountain Region. [FR Doc. 84 -24459 Filed 9 - 14 - 84; 8:45 am] BILLING CODE 4910 - 13 -M