47-12-01 DOUGLAS: (Was Mandatory Note 14 of AD-762-7.) Applies to All C-54 and R5D Series Airplanes, and the Following DC-4 Airplanes: 42904 to 42943, Inclusive; 42948 to 42952, Inclusive; 42982 to 42996, Inclusive; 43065 to 43069, Inclusive; 43071; 43072; and 43102. DC-4 Production Airplanes Nos. 43070, 43090, and Subsequent Except 43102, as Noted Above, Will be Modified Prior to Delivery. \n\n\tTo be accomplished not later than January 1, 1948. \n\n\tIf the clear-view panel in the windshield is opened in flight when the landing gear and flaps are extended, exhaust fumes enter the cabin. This causes considerable discomfort to passengers and may create a hazard which would affect the safe operation of the airplane. In order to prevent the exhaust fumes from entering the cabin under these conditions, all openings around the control cables and flap buss system at the side of the fuselage must be sealed and additional means for exhausting main cabin and cockpit ventilating air provided, unless tests made by the operator of the individual airplane show no unsatisfactory condition of carbon monoxide entering cabin with open windows when landing gear down and flaps extended. \n\n\t(Douglas Service Bulletin No. DC-4, No. 32, covers this same subject.)