47-06-07 DOUGLAS: (Was Service Note 12 of AD-618-3, Supplement 1; Service Note 15 of AD-669-3, Supplement 1.) Applies to All DC3 Series Aircraft. \n\n\tTo be accomplished not later than the next periodic inspection, or in the case of scheduled air carrier aircraft, at the next major inspection. \n\n\tCheck the pull necessary to trip the trigger on the CO2 fire extinguishing system. If the trigger pull exceeds 50 pounds due to wear of the aluminum conduit covering the fire extinguisher release cable, this conduit must be replaced immediately. This procedure is to be repeated at each specified inspection period until such time as the aluminum cable conduit is replaced by stainless steel conduit. \n\n\t(Douglas Service Bulletin DC3 No. 246 dated November 22, 1946, covers this same subject.)