80-22-07 MCDONNELL DOUGLAS: Amendment 39-3958. Applies to Model DC-6, DC-6A, DC-6B airplanes certificated in all categories including military models R6D and C-118 eligible for civil certification, incorporating nose landing gear upper torque link assembly P/N 8488A-46. \n\n\tCompliance is required as indicated unless already accomplished. \n\n\tTo prevent failure of the nose landing gear upper torque link which could result in nose gear collapse accomplish the following: \n\n\t(a)\tWithin 100 hours' time in service from the effective date of this AD unless already accomplished in the last 200 hours' time in service and thereafter at intervals not to exceed 300 hours' time in service since the last such inspection; inspect the nose landing gear upper torque link P/N 8488A-46-1 for cracks at the shoulder recess corner radius, by dye penetrant methods after removing paint per standard shop practice. Do not use a wood (or other) wedge to preload the lugs. \n\n\t(b)\tIf cracks are found:(1)\tThe cracked part may be replaced with a like serviceable part of the same part number provided that the replacement part is dye penetrant inspected for cracks within 300 hours' time in service from installation and thereafter at intervals not to exceed 300 hours' additional time in service since the last such inspection, or \n\n\t\t(2)\tThe cracked part may be replaced with a like serviceable part of the same part number, reworked as shown on Figures 2 and 3 of Douglas Aircraft Company Service Bulletin No. 641 dated October 18, 1955, and the repetitive inspection requirements of paragraph (a) of this AD are applicable, or \n\n\t\t(3)\tThe cracked part may be replaced by like serviceable P/N 8488A-46A-1 of improved design in which case no additional inspections are required by this AD. \n\n\t(c)\tIf no cracks are found: \n\n\t\t(1)\tReturn P/N 8488A-46-1 part to service provided that it is inspected per paragraph (a) of this AD at intervals not to exceed 300 hours' time in service since the last such inspection. \n\n\t\t(2)\tReturn P/N 8488A-46-1 part reworked per Figure 5 or Figure 2 of Douglas Aircraft Service Bulletin No. 461 dated October 13, 1955 to service provided that it is inspected per paragraph (a) of this AD at intervals not to exceed 300 hours' time in service since the last such inspection. \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)\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\tThis supersedes AD 54-23-02. \n\n\tThis amendment becomes effective November 3, 1980.