60-02-05 DOUGLAS: Amdt. 84 Part 507 Federal Register January 16, 1960. Applies to the Following Aircraft: DC-6 Serial Numbers 42878, 43030 To 43033 Inclusive, 43136, 43148 To 43151 Inclusive, 43212 To 43214 Inclusive, and 43216 To 43218 Inclusive. \n\n\tCompliance required as indicated. \n\n\tTo detect cracking of the lower front and center spar cap tangs at intersection with lower fuselage attach angle the following must be accomplished on affected DC-6 aircraft having in excess of 16,000 hours service time. \n\n\t(a)\tInspect lower front spar cap at the nearest maintenance inspection period to 200 hours service time unless similar inspection has been conducted within the last 1,250 hours service time. \n\n\t(b)\tInspect lower front and center spar caps at maintenance inspection period nearest to each succeeding 1,250 hours service time. \n\n\t\t(1)\tAt the first 1,250-hour inspection period, the holes located in aft tang of front spar lower cap and fuselage attach angle should be enlarged and new attachments installed. (Kit "A" of Douglas SB A-845 or equivalent.) \n\n\t\t(2)\tAt next regularly scheduled overhaul period, the holes located in forward tang of front spar lower cap should be enlarged and new attachments installed. (Kit "A" of Douglas SB A-845 or equivalent.) \n\n\t(c)\tIf spar cap cracks are found, temporary rework per Drawing No. 3645935 (Kit "B"), or permanent rework per Drawing No. 5765079 (Kit "C") or equivalent, must be accomplished. If temporary rework is installed, inspection must be repeated at 1,250-hour intervals for a maximum of 3,200 hours service time, at which time permanent rework per Drawing No. 5765079 (Kit "C"), or equivalent, must be accomplished. \n\n\t(d)\tAll aircraft must have permanent rework per Drawing No. 5765079 (Kit "C"), or equivalent, accomplished within next 6,400 hours service time. \n\n\t(e)\tAfter installation of permanent rework per Kit "C", or equivalent, operators may revert to normal repetitive inspection periods not to exceed 3,200 hours service time. \n\n\t(Douglas Service Bulletin DC-6 No. A-845 dated July 31, 1959, covers this same subject.)