75-03-01 BOEING: Amendment 39-2074 as amended by Amendment 39-2421 and 39-3502 is further amended by Amendment 39-3737. Applies to all Boeing Model 707-300, -300B, - 300C, and -400 series airplanes listed in Boeing Service Bulletin No. 3157, Revision 4, or later FAA approved revisions upon the accumulation of the following number of landings since new: \n\nModels\n707-300, -400\t13,000 or more landings \n707-300B\t8,000 or more landings\n707-300C\t8,000 or more landings \n\n\tCompliance required as indicated. \n\tTo detect cracks in the upper wing skin splice plate at W.S. 360, accomplish the following: \n\tA.\tWithin the next 50 landings, unless accomplished within the last 350 landings, and at intervals thereafter not to exceed 400 landings, inspect the upper wing splice plate at station 360 in accordance with (1), (2), or (3) below. Special attention should be focused in the area of stringer 11 as it is in the high stressed area of the splice plate. If cracks are found, repair priorto further flight in accordance with paragraph B below. \n\t\t(1)\tX-Ray inspect per Boeing Service Bulletin No. 3157, Revision 3 and visually inspect the splice plate by removing the aerodynamic sealant between the wing skins from front to rear spar. This inspection method is acceptable for only two successive inspections after the effective date of this amendment. \n\t\t(2)\tLow frequency eddy current inspect as specified in Boeing Service Bulletin No. 3157, Revision 7, or inspections approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. \n\t\t(3)\tInspect in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. \n\tB.\tIf cracks are found, repair prior to further flight in accordance with Boeing Service Bulletin No. 2510, Revision 3, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. The repetitive inspections of paragraph A. must be accomplishedin areas not covered by repairs per Part VII of Boeing Service Bulletin No. 2510, Revision 3, or later FAA approved revisions. \n\tC.\tThe inspections required by this AD may be terminated when the following is accomplished: \n\t\t(1)\tSplice plate, skin and rib cap fastener holes are oversized to remove fatigue material per Part IV of Boeing Service Bulletin No. 2510, Revision 3, or later FAA approved revisions, and complete external doublers are installed in accordance with Part VIII of Boeing Service Bulletin No. 2510, Revision 3, or later FAA approved revisions, or \n\t\t(2)\tOther modifications are made in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. \n\tD.\tFor the purpose 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 hours' time in service by the operator's fleet average time from takeoff to landing for the airplane type. \n\tE.\tUpon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the change for that operator. \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). \n\tAll 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. The documents may be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington. \n\tThis supersedes Amendment 39-1829 (39 F.R. 15027), AD 74-09-07, as amended by Amendment 39-2002. \n\tAmendment39-2074 became effective January 27, 1975. \n\tAmendment 39-3421 became effective December 4, 1975. \n\tAmendment 39-3502 became effective July 3, 1979. \n\tThis Amendment 39-3737 becomes effective April 17, 1980.