48-49-03 DOUGLAS: Applies to All DC-6 Airplanes. \n\n\tCompliance required not later than March 1, 1949. \n\n\tTo reduce the probability of a loss of power for electrical circuits considered to be essential in flight, these essential circuits were designed to be connected directly to the master bus. Other less essential circuits are connected to the master bus through a 500-ampere Burndy limiter (fuse). \n\n\tIn an undetermined number of aircraft some of the essential circuits were inadvertently connected to the distribution bus rather than to the master bus. \n\n\tIt is necessary, therefore, that all DC-6 aircraft be inspected and such rewiring as necessary be done to assure that the following circuit protectors are connected to the master bus: \n\n\tRadio Master (B1-102), Fuel Booster Pumps (B1-63, 97), Invertor Power (B1-111, 116), Propeller Booster (Curtiss Propellers only, F1-28, 29), Propeller Control (Curtiss: B1-141, 142, 143, 144. Hamilton Standard: B1-188, 189, 190, 191), Propeller Synchronizer (B1-145), Governor Control (Hamilton Standard only, B1-192), Generator Control Panel (Eclipse Generator System only, B1-246, 247, 248, 249. Reference Douglas Service Bulletin DC-6 No. 329. \n\n\t(Douglas Service Letter A214-T.3338/TFW dated October 22, 1948 covers this same subject.)