48-09-01 DOUGLAS: Applies to C-54 and DC-4 Aircraft. \n\n\tTo be accomplished not later than April 15, 1948. \n\n\tBecause of the hazards involved, the transfer of fuel between tanks must be prohibited. The following placard shall be installed in the cockpit in full view of the pilots: \n\n\t"Fuel cross-feed system not intended for transferring fuel from one tank to another and should not be used for this purpose. When using crossfeed system, turn off tank(s) not in use." \n\n\tIn addition to the placard, the FAA Approved Flight Manual must be revised to incorporate proper fuel system operation procedures in accordance with the above placard. Approved Flight Manual pages may be obtained from the airplane manufacturer.