79-19-02 MCDONNELL DOUGLAS: Amendment 39-3555. Applies to certain Model DC-9 series airplanes, certificated in all categories, including Military Type C-9A, C-9B and VC-9C, serial numbers corresponding to fuselage numbers 1 through 839 as identified in McDonnell Douglas Service Bulletin 55-28, Revision 4, dated May 18, 1979. \n\n\tCompliance required within the next 3400 hours' time-in-service unless already accomplished within the past 200 hours' time-in-service, and thereafter at intervals not to exceed 3600 hours' time-in-service, on all airplanes with over 5000 hours' time-in-service as of, and after, February 13, 1978. Accomplishment of superseded AD 78-01-12 may be credited as accomplishment of this AD until the effective date of this AD. \n\n\t(a)\tPerform an X-ray inspection of the elevator spars, P/N 9918450-1 or -501 in accordance with instructions contained in paragraph 2 of McDonnell Douglas DC-9 Service Bulletin 55-28, Revision 4, dated May 18, 1979. \n\n\t(b)\tCracked parts found during any of the inspections of paragraph (a) which do not exceed the crack limits and McDonnell Douglas DC-9 Service Bulletin 55-28, Revision 4, dated May 18, 1979 may be continued in service. However, in addition to the 3600 hour repetitive general inspection requirements of paragraph (a), the area 12 inches inboard and outboard of all cracks must be X-ray or dye penetrant inspected at intervals not to exceed the following: \n\n\t\t(1)\tLength of longest crack up to 2 inches - 800 hours' time-in-service. \n\n\t\t(2)\tLength of longest crack between 2 and 4 inches - 400 hours' time-in-service. \n\n\t(c)\tIf cracks are found during any reinspections of paragraphs (a) or (b) which exceed the crack limits of McDonnell Douglas DC-9 Service Bulletin 55-28, Revision 4, dated May 18, 1979, the cracked spar must be repaired or replaced before further flight. If the cracked spar is repaired per McDonnell Douglas Service Sketch 27378, the inspection procedures in paragraph (a) of this AD must be accomplished within 1800 hours' time-in-service after the repair and at intervals of 1800 hours' time-in-service thereafter. \n\n\t(d)\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(e)\tIf the original 7075-T651 spars (P/N 9918450-1 or -501) are replaced with 7075-T7351 spars (P/N 9918450-503), the inspection requirements of this AD will not apply to that airplane. \n\n\t(f)\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(g)\tUpon request of operator, an FAA maintenance inspector, subject to prior approval of the Chief, Aircraft Engineering Division, FAA Western Region may adjust the initial and 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 AD 78-01-12, Amendment 39-3119. \n\n\tThis amendment becomes effective September 13, 1979.