76-13-01 BOEING: Amendment 39-2648 as amended by Amendment 39-2666. Applies to Boeing Model 727 series airplanes, categorized as Group I and II in Boeing Service Bulletin No. 727-53-128, Revision 2, or later FAA approved revisions, and certificated in all categories. \n\tCompliance required as indicated. \n\tTo detect corrosion and/or cracking in the lower body skin (1) along BBL 0 from Body Stations 360 to 740 and along Stringers 28L and 28R from the forward end of the body fairing to Body Station 740 on Group I airplanes and (2) along Stringers 27L and 27R from the forward end of the body fairing to Body Station 740 on Group I and II airplanes, accomplish the following: \n\tA.\tWithin the next six (6) months from the effective date of this AD, unless accomplished within the last eighteen (18) months, and thereafter at intervals not to exceed twenty-four (24) months, inspect in accordance with the external/internal visual inspection procedures of Figures 1 and 3 of Boeing Service Bulletin No. 727-53-128, Revision 2, or later FAA approved revisions, or equivalent procedures approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region; or,\n \tB.\t1.\tWithin eighteen (18) months from the effective date of this AD, unless accomplished within the last eighteen (18) months, and thereafter at intervals not to exceed thirty- six (36) months, inspect in accordance with the external/interval visual inspection procedures of Figures 1 and 3 of Boeing Service Bulletin No. 727-53-128, Revision 2, or later FAA approved revisions, or equivalent procedures approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region; and, \n\t\t2.\tWithin the next six (6) months after the effective date of this AD, and thereafter at intervals not to exceed six (6) months until an external/interval inspection is performed pursuant to paragraph B.1 above, inspect in accordance with the external visual inspection procedures of Figure 1 of Boeing Service Bulletin No.727-53-128, Revision 2, or later FAA approved revisions, or an equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region; and, \n\t\t3.\tWithin twenty-four (24) months after each external/ internal inspection conducted per paragraph B.1 above, and thereafter at intervals not to exceed six (6) months until the next external/internal inspection per paragraph B.1 is performed, inspect in accordance with the external visual inspection procedures of Figure 1 of Boeing Service Bulletin No. 727-53-128, Revision 2, or later FAA approved revisions, or an equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. \n\tC.\tIf the inspections conducted per paragraphs A or B reveal corrosion and/or cracking, repair in accordance with Boeing Service Bulletin No. 727-53-128, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. \n\tD.\tAreas repaired in accordance with paragraph C, the Boeing 727 Structural Repair Manual, or Boeing Service Bulletin No. 727-53-73, or later FAA approved revisions, need not comply with the inspection requirements of this AD, provided faying surface sealant was applied to the faying surfaces. Areas in which corrosion and/or cracking is not found, must be reinspected per paragraph A or B until terminating action per paragraph F is accomplished. \n\tE.\tThe left and right had ram air inlet doors and splitter vane need only be removed every other external inspection of paragraph B.2 and B.3. \n\tF.\tModification in accordance with Part I - paragraph C or Part II - paragraph C, as applicable, of Boeing Service Bulletin No. 727-53-128, or later FAA approved revisions, or an installation approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, constitutes terminating action for the areas specified in the service bulletin. \n\tG.\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 in this AD, if the request contains substantiating data to justify the increase 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 also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington.\n \n\tAmendment 39-2648 became effective July 2, 1976. \n\tThis amendment 39-2666 becomes effective July 20, 1976.