68-15-01\tBOEING: Amendment 39-624. Applies to Model 727 Series airplanes listed in Parts I, II, and III of paragraph I, Planning Information . . . , 1. Airplanes Affected, of Boeing Service Bulletin No. 55-18(R-6) dated June 15, 1967, as set forth on pages 1 and 2 thereof, and hereafter referred to as Part I of 1. Airplanes Affected or Part II and Part III of 1. Airplanes Affected. \n\n\tCompliance required as indicated. \n\n\tTo detect cracks or to prevent further cracks in the lower chord of the horizontal stabilizer rear spar, accomplish the following: \n\n\t(a)\tUnless already accomplished within the last 750 hours' time in service, within the next 50 hours' time in service after the effective date of this AD or prior to 650 hours' time in service after April 10, 1966, whichever is later, and thereafter at intervals not to exceed 800 hours' time in service, inspect Model 727 Series airplanes with 350 or more hours' time in service on April 10, 1966, listed in Part I of 1. Airplanes Affected in accordance with paragraph (e) hereof. \n\n\t(b)\tUnless already accomplished within the last 750 hours' time in service, within the next 50 hours' time in service after the effective date of this AD or prior to the accumulation of 1,000 hours' time in service, whichever is later, and thereafter at intervals not to exceed 800 hours' time in service, inspect Model 727 Series airplanes with less than 350 hours' time in service on April 10, 1966, listed in Part I of 1. Airplanes Affected, in accordance with paragraph (e) hereof. \n\n\t(c)\tUnless already accomplished within the last 100 hours' time in service, within the next 700 hours' time in service after the effective date of this AD, and thereafter at intervals not to exceed 800 hours' time in service, inspect Model 727 Series airplanes with 2,300 or more hours' time in service on the effective date of this AD listed in Part II and Part III of 1. Airplanes Affected in accordance with paragraph (e) hereof. \n\n\t(d)\tUnlessalready accomplished within the last 100 hours' time in service, before the accumulation of 3,000 hours' time in service, and thereafter at intervals not to exceed 800 hours' time in service, inspect Model 727 Series airplanes with less than 2,300 hours' time in service on the effective date of this AD listed in Part II and Part III of 1. Airplanes Affected in accordance with paragraph (e) hereof. \n\n\t(e)\tVisually inspect for cracks in the lower chord of the horizontal stabilizer rear spar, Stabilizer Stations 110.00 through 225.54, in accordance with Paragraph II, Accomplishment Instructions, Part I - Inspection Data, of Boeing Service Bulletin No. 55-18(R-2); dated January 3, 1966, or later FAA approved revision. \n\n\t(f)\tIf cracks are found, repair before further flight (except that the airplane may be flown in accordance with FAR 21.197 to a base where the repair can be performed) in accordance with Paragraph II, Accomplishment Instructions, Part III - Repair Data, of Boeing Service Bulletin No. 55-18(R-2), dated January 3, 1966, or later FAA approved revision, or an equivalent approved by the Chief, Aircraft Engineering Division, FAA Western Region. After the repair is accomplished, the repetitive inspections required by this AD may be discontinued for areas repaired. \n\n\t(g)\tIf cracks are not found, the aircraft may be modified in accordance with Paragraph II, Accomplishment Instructions, Part II - Preventive Modification Data, of Boeing Service Bulletin No. 55-18(R-2) or later FAA approved revision. After the modification is accomplished, the repetitive inspections required by this AD may be discontinued for areas modified. \n\n\tNOTE: A repair in accordance with Service Bulletin 55-18 or 55-18(R-1) is considered a preventive modification. \n\n\t(h)\tUpon request of the operator, an FAA maintenance inspector, subject to prior approval of the Regional Director, FAA Western 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 increase for that operator. \n\n\tThis supersedes Amendment 39-208 (31 F. R. 4283), AD 66-07-02. \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. 522(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to the Boeing Company, Commercial Airplane Division, Post Office Box 707, Renton, Washington 98055. These documents may also be examined at Room 406, Building A, FAA Western Region Office, 5651 West Manchester Avenue, Los Angeles, California 90045 and FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. An historical file on this AD which includes the incorporated material in full is maintained by the FAA at its Headquarters in Washington, D.C. and at FAA Western Region. \n\n\tThis amendment becomes effective July 20, 1968.