78-07-05 MCDONNELL DOUGLAS: Amendment 39-3176 as amended by amendment 39-3467. Applies to Model DC-9 and C-9 series airplanes, certificated in all categories, which correspond to the factory serial numbers as listed below. \n\n\n45695 thru 45749\n47389 thru 47397 \n45770 thru 45799\n47399 thru 47482 \n45825 thru 45847\n47484 thru 47514 \n45863 thru 45876\n47516 thru 47557 \n47000 thru 47386\n47559 thru 47764 \n\n 47769 \n\n 47771 \n\t\t\t\n\tCompliance required as indicated, unless already accomplished: \n\n\tTo prevent possible failure of the over-wheelwell fuselage frame(s) lower fittings manufactured with 7075-T6 aluminum alloy material, accomplish the following: \n\n\ta.\tFor airplanes with 12,000 or more hours time in service on the effective date of this AD, which have not had new frames installed, within the next 3400 hours time in service or 12 calendar months, whichever occurs earlier, and thereafter at intervals not to exceed 8000 hours time in service or 37 calendar months, whichever occurs earlier, comply with the program of inspections established in Paragraph (c), below. \n\n\tb.\tFor airplanes with less than 12,000 hours time in service as of the effective date of this AD, comply with Paragraph (c), below, prior to the accumulation of 15,400 hours time in service or 50 calendar months, whichever occurs earlier, and thereafter at intervals not to exceed 8000 hours time in service or 37 calendar months, whichever occurs earlier. \n\n\tc.\tVisually inspect for evidence of cracking, using optical inspection aids with a minimum of 2X magnification, the fore and aft webs, flanges and radii, in the areas of the frame lower fitting, as shown in Sketch No. 2765 of McDonnell Douglas Service Bulletin 53-131 dated February 24, 1978 or later FAA approved revision, (hereinafter referred to as SB 53-131). \n\n\td.\tIf no cracks are found: \n\n\t\t(1)\tClean and spray the pocket and adjacent areas of the frame fitting with corrosion inhibiting compound, per DAC SRM, Chapter 51-10-3, and perform repetitive inspections and corrosion inhibiting treatment at intervals not to exceed 8,000 hours time in service or 37 calendar months, whichever occurs earlier; or \n\n\t\t(2)\tRepair per Option 1 of SB 53-131 and conduct repetitive inspection at intervals not to exceed 16,000 hours time in service or 54 calendar months whichever occurs earlier; or \n\n\t\t(3)\tReplace with new part(s) per Paragraphs f.2 or f.3 and comply with the applicable program of repetitive inspections and/or corrective actions per this AD. \n\n\te.\tIf cracks are found which are within the limits of Figure 1 of SB 53-131, aircraft may be continued in service provided that \n\n\t\t(1)\tRepetitive inspections are conducted at intervals not to exceed 3,400 hours time in service if an adjacent frame does not have cracks in pocket area or has been repaired per Option 1 of SB 53-131; or \t\t(2)\n\n\tRepetitive inspections are conducted at intervals not to exceed 1,700 hours time in service if adjacent frame(s) hasunrepaired flange cracks within limits as outlined on Figure 1 of SB 53-131. \n\n\tf.\tIf cracks are found, which are beyond the limits of Figure 1, but within the limits of Figure 2 of SB 53-131, before further flight. \n\n\t\t(1)\tRepair per Option 1 of SB 53-131 and conduct repetitive inspections at intervals not to exceed 8,000 hours time in service or 27 calendar months, whichever occurs earlier; or \n\n\t\t(2)\tReplace with a new part(s) of the same design made from 7075-T6 aluminum material; or \n\n\t\t(3)\tReplace with a new part(s) of the same design made from 7075-T73 aluminum alloy material. \n\n\tg.\tIf cracks are found which are beyond the limits of Figure 2 of SB 53-131, before further flight: \n\n\t\t(1)\tReplace with a new part(s) of the same design made from 7075-T6 aluminum alloy material; or \n\n\t\t(2)\tReplace with a new part(s) of the same design made from 7075-T73 aluminum alloy material. \n\n\th.\tThe requirements per this AD may be terminated for that frame(s) only, when both theright and left hand fittings, made from 7075-T73 aluminum alloy material, have been installed. \n\n\ti.\tIf new parts have been installed per f(2) or g(1) for the stations specified, the requirements of this AD may be discontinued for that part(s) only, until the new part(s) has accumulated 15,400 hours time in service or within 50 calendar months after the part(s) has been replaced, whichever occurs earlier, at which time reinstate the program of repetitive inspections and/or corrective action per this AD. \n\n\tj.\tEquivalent inspection procedures and repairs may be used when approved by the Chief, Aircraft Engineering Division, FAA, Western Region. \n\n\tk.\tSpecial flight permits may be issued in accordance with FAR's 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or maintenance required by this AD. \n\n\tl.\tUpon request of the 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 Amendment 39-3149 (43 FR 9587), AD 78-05-03. \n\n\tAmendment 39-3176 became effective April 6, 1978. \n\n\tThis amendment 39-3467 becomes effective May 18, 1979.