80-08-09 R1 MCDONNELL DOUGLAS: Amendment 39-3743 as amended by Amendment 39-4209. Applies to Model DC-9-10, -20, -30, -40, -50 series airplanes (including military C9A, C9B, and VC9C airplanes) certificated in all categories. \n\n\tCompliance required as indicated, unless already accomplished. To prevent possible loss of structural integrity of the horizontal stabilizer rear spar, accomplish the following: \n\n\t(a)\tOn the accumulation of 20,000, or more, hours' total time in service, but less than 30,000 hours' total time in service, within 1,200 hours' additional time in service from the effective date of this AD, inspect the left and right horizontal caps by visual and eddy current methods per paragraph 2 of McDonnell Douglas Alert Service Bulletin A55-31, Revision 1, dated March 18, 1980. \n\n\t(b)\tOn the accumulation of 30,000, or more, hours' total time in service, within 800 hours' additional time in service from the effective date of this AD, inspect the left and right horizontal stabilizer upper and lower rear spar caps by visual and eddy current methods per paragraph 2 of McDonnell Douglas Alert Service Bulletin A55-31, Revision 1, dated March 18, 1980. \n\n\t(c)\tIf minor cracks are found which are within the limits of Figure 1 of Service Bulletin A55-31, remove minor cracks by trimming out as shown in Figure 1 of paragraph 2 of McDonnell Douglas Alert Service Bulletin A55-31, Revision 1, dated March 18, 1980. \n\n\t(d)\tHorizontal stabilizer spars which have been subjected to crack trim-out per paragraph (c) of this AD, must be reinspected by visual and eddy current methods within 800 hours' additional time in service after accomplishment of paragraph (c), and thereafter at intervals not to exceed 800 hours' time in service until or prior to the accumulation of 3,200 hours' time in service since accomplishment of paragraph (c) of this AD, at which time the spar cap must be removed and replaced with a like serviceable part. \n\n\t(e)\tIf cracks are found which are beyond the trim-out limits of Figure 1 of Service Bulletin A55-31, remove and replace with like serviceable part, and reinspect by visual and eddy current methods per paragraph 2 of McDonnell Douglas Alert Service Bulletin A55-31, Revision 1, dated March 18, 1980, prior to the accumulation of 20,000 hours' additional time in service on the replacement part. \n\n\t(f)\tIf no cracks are found as a result of any of the inspections required by this AD, reinspect the left and right horizontal stabilizer upper and lower rear spar caps by visual and eddy current methods per paragraph 2 of McDonnell Douglas Alert Service Bulletin A55-31, Revision 1, dated March 18, 1980, at intervals not to exceed 6,400 hours' time in service since the last inspection. \n\n\t(g)\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections required by this AD. \n\n\t(h)\tAlternative inspections, modifications or other actions which provide an equivalent level of safety may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region. \n\n\t(i)\tThe replacement of horizontal stabilizer upper and lower rear spar caps in accordance with Part 2 Accomplishment Instructions of McDonnell Douglas DC-9 Service Bulletin 55-31 dated February 27, 1981, or later revisions approved by the Chief, Los Angeles Area Aircraft Certification Office, Northwest Region, constitutes terminating action for the repetitive inspections required by paragraphs (a) through (f) of this AD. \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 McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director, Publications and Training, C1-750 (54-60). \n\n\tThese documents also may be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington 98108 or Los Angeles Area Aircraft Certification Office, 4344 Donald Douglas Drive, Long Beach, California 90808. \n\n\tAmendment 39-3743 became effective May 12, 1980. \n\n\tThis Amendment 39-4209 becomes effective September 15, 1981.