75-09-04 R1 BOEING: Amendment 39-2174 as amended by Amendment 39-4926. Applies to Boeing Model 727 series airplanes, certificated in all categories, listed in Boeing Service Bulletin 727-55-62, or later FAA approved revisions (line numbers 1 through 641, inclusive). Compliance required as indicated. \n\n\tTo detect cracks in the horizontal stabilizer rear spar center section fitting, accomplish the following: \n\n\tA.\tWithin the next 750 flight hours after the effective date of this AD, unless accomplished within the last 2250 flight hours, inspect the horizontal stabilizer rear spar center section fitting in accordance with Paragraph III of Boeing Service Bulletin 727-55-62, or later FAA approved revisions or in a manner approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\t\t1.\tIf no cracks are found in the fitting, repeat the inspections at intervals not to exceed 3000 flight hours, until replaced per Paragraph B. \n\n\t\t2.\tIf a crackis found at the upper or lower flanges of the fitting and is within the allowable limits specified in Figure 2 of Boeing Service Bulletin 727-55-62, or later FAA approved revisions, prior to further flight, stop drill the crack per the service bulletin. Inspect the stop drilled areas for crack growth at 1500 flight hour intervals, until repaired or replaced in accordance with Boeing Service Bulletin 727-55-62, or later FAA approved revisions, or in a manner approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\t\t3.\tIf a crack is found in any of the hinge lugs and is within the allowable limits specified in Boeing Service Bulletin 727-55-62, or later FAA approved revisions, before further flight, repair the fitting in accordance with Figure 3 of the service bulletin, or in a manner approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. Inspect the repaired fitting thereafter at intervals not to exceed 1500 flight hours. \n\n\t\t4.\tIf a crack at any location is beyond the allowable limits specified in Boeing Service Bulletin 727-55-62, or later FAA approved revisions, before further flight, repair in a manner approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, or replace the fitting with a new improved fitting per Paragraph B. \n\n\tB.\tAs terminating action for this AD, replace the horizontal stabilizer rear spar center section fitting with a new improved 7075-T73 aluminum allow fitting. \n\n\tC.\tAirplanes having cracked horizontal stabilizer rear spar center section fittings which require replacement under this AD may be flown in accordance with FAR 21.197 to a base where the replacement can be accomplished. \n\n\tD.\tUpon request of an operator, an FAA Maintenance Inspector, subject to the prior approval of the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, may adjust the inspection intervals in this AD, if the request contains substantiating data to justify the increase for that operator. \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). \n\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 Mountain Region, 17900 Pacific Highway South, Seattle, Washington. \n\n\tAmendment 39-2174 became effective April 29, 1975. \n\n\tThis Amendment 39-4926 becomes effective January 22, 1985.