75-24-01 BOEING: Amendment 39-2424. Applies to all Boeing 707-300, and -400 series airplanes with 13,000 or more landings; all 707-300B airplanes with 11,000 or more landings; and all 707-300C series airplanes with 8,000 or more landings, listed in Boeing Service Bulletin No. 3157 Revision 3, certificated in all categories. Compliance required as indicated. \n\tTo detect cracks in the upper wing skin splice plate at W. S. 360, within the next 50 landings: \n\t(1)\tConduct the low frequency eddy current inspection in accordance with Boeing Field Service Message M-7010-1256, dated October 9, 1975, unless already accomplished, or \n\t(2)\tRemove the aerodynamic sealant between the upper wing skins at W. S. 360 from the front spar to the rear spar and visually inspect for a crack in the splice plate, unless accomplished since October 3, 1975. If cracks are found, repair in accordance with Boeing Service Bulletin No. 2510, Revision 3, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA, Northwest Region. \n\tThis is a one-time inspection. AD 75-03-01 (Amendment 39-2074) will be amended to provide for inspections similar to those provided herein. Telegraphic AD on this subject on October 15, 1975, is hereby superseded. \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 also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment becomes effective upon publication in the Federal Register for all persons except those to whom it was made effective immediately by telegram dated October 17, 1975.