73-09-02 MCDONNELL DOUGLAS: Amendment 39-1628 as amended by Amendments 39-1926, 39-2004 and 39-2850 is further amended by Amendment 39-3401. Applies to Model DC-9-10 Series Airplanes certificated in all categories. \n\n\tCompliance required as indicated: \n\n\tTo detect fatigue cracks in the fuselage frames (P/N 9915590, 9958198, 9958200 and 9958202) at fuselage stations 503, 525, or 544 accomplish the following: \n\n\tA.\t1.\tFor airplanes with 10,000 hours or more time in service on the effective date of this A.D., unless already accomplished within the last 500 hours time in service prior to the effective date of this A.D., within the next 1000 hours time in service and thereafter at intervals not to exceed 2000 hours time in service from the last inspection, inspect the left and right hand lower sections of the fuselage frames P/N 9915590, 9958198, 9958200, and 9958202, in accordance with the instructions and procedures of paragraph B, below. \n\n\t\t2.\tFor airplanes with less than 10,000 hours time in service on the effective date of this A.D., comply with paragraph (B) before the accumulation of 11,000 hours time in service. \n\n\tB.\t1.\tVisually inspect for evidence of cracking, using dye penetrant methods and/or a magnifying glass with a minimum of 4-power, or an equivalent method approved by the Chief, Aircraft Engineering Division, FAA Western Region, the areas between and surrounding the two upper bolts (including the inboard flange of the lower section of the frame) which attach the rear face of the lower section of the fuselage frames (9915590, 9958198, 9958200 and 9958202) to the transverse floor beam member at fuselage stations 503, 525, and 544, both left and right hand sides. \n\n\t\t2.\tIf cracks are found: \n\n\t\t\ta.\tReplace with a new part(s) of the same design; or, \n\n\t\t\tb.\tRepair per an equivalent method approved by the Chief, Aircraft Engineering Division, FAA Western Region; or \n\n\t\t\tc.\tRepair per the instructions specified in Douglas Service Bulletin 53-117, dated December 21, 1973, or later FAA-approved revisions. \n\n\t\t3.\tIf a new part(s) of the same design are installed per B.2.a., or repairs accomplished per B.2.b., above, the repetitive inspections per this A.D. may be discontinued for that part(s) only, until the new part has accumulated an additional 10,000 hours time in service, at which time reinstate the program of repetitive inspections and/or corrective action per this A.D. \n\n\t\t4.\tIf a repair incorporating Service Bulletin 53-117, dated December 21, 1973, or later FAA-approved revisions, per B.2.c., above, or an equivalent repair approved by the Chief, Aircraft Engineering Division, FAA Western Region, is accomplished, the inspections required by this A.D. may be terminated, and normal, routine maintenance practices reinstated. \n\n\tAmendment 39-1628 became effective May 30, 1973. \n\n\tAmendment 39-1926 became effective August 26, 1974. \n\n\tAmendment 39-2004 became effective November 13, 1974. \n\n\tAmendment 39-2850 became effective March 20, 1977. \n\n\tThis amendment 39-3401 becomes effective January 31, 1979.