83-02-09 BOEING: Amendment 39-4549. Applies to Model 707, 727C, and 727-100C series airplanes certificated in all categories listed in Boeing Service Bulletins Number 2999, Revision 3, and Number 727-52-79, Revision 4, or later FAA approved revisions. \n\n\tCompliance required as indicated unless already accomplished. \n\n\tTo detect cracking of the main cargo door skin and frames and to prevent rapid decompression or loss of a portion of the door accomplish the following in accordance with Boeing Service Bulletins Number 2999, Revision 3, or Number 727-52-79, Revision 4, or later FAA approved revisions. \n\n\tA.\tWithin the next 500 landings after the effective date of this AD, or prior to accumulating 25,000 landings, whichever occurs later, inspect for cracks in the main cargo door skin between B.S. 505 and B.S. 595 from the lower edge of the door hinge downwards a minimum of six inches, and six inches above and three inches below the center line of stringer 10. Inspect visually or by using eddy current or X-ray procedures as specified in the applicable service bulletin. \n\n\tB.\tRepeat the inspections at intervals not to exceed one of the following until the airplane is modified in accordance with the applicable service bulletin listed in paragraph D: \n\n\t\t1.\t500 landings, if visually inspected, or \n\t\t2.\t750 landings, if eddy current inspected, or \n\t\t3.\t1,000 landings, if X-ray inspected. \n\n\tC.\tCracks are to be repaired prior to further pressurized flight in accordance with the following service bulletins: \n\n\t\t1.\tFor Boeing Model 707/720 series airplanes: Boeing Service Bulletin No. 2999, Revision 3, or later FAA approved revisions. \n\n\t\t2.\tFor Boeing Model 727C and 727-100C series airplanes: Boeing Service Bulletin No. 727-52-79, Revision 4, or later FAA approved revisions. \n\n\tD.\tModification in accordance with the Boeing Service Bulletin listed in paragraph C. or later FAA approved revisions constitutes terminating action for this AD. \n\n\tE.\tForthe purpose of this AD, and when approved by an FAA maintenance inspector, the number of landings may be computed by dividing each airplane's time in service by the operator's fleet average time from takeoff to landing for the aircraft type. \n\n\tF.\tAircraft may be ferried to a maintenance base for repair in accordance with FAR Sections 21.197 and 21.199. \n\n\tG.\tAlternate means of compliance which provide an equivalent level of safety may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tNOTE: Acceptable incorporation of the Boeing Model 707/720 Supplemental Structural Inspection Document (SSID) into the approved airplane maintenance program of a B707/720 operator constitutes an approved alternate means of AD compliance for B707/720 airplanes. \n\n\tThe manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1).All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124. These documents may also be examined at the FAA, Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment becomes effective March 31, 1983.