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August 1, 1940, under Certificate and Inspection Division Release No. 21, which required a 100° F. heat rise with suitable indicators or a 40° F. heat rise with an auxiliary emergency deicing system controllable from the cockpit, utilizing alcohol, anilol, etc. All air carrier aircraft had to comply with this regulation by October 1, 1940.
Steps were immediately taken to eliminate the probability of ice forming in this type of carburetors by increasing heat rise to 100° F.
In addition, intensive studies of icing with various types of carburetors, etc., are now being conducted at the Bureau of Standards through the combined cooperation of the Navy Department, War Department, National Advisory Committee for Aeronautics, Civil Aeronautics Administration, and the Safety Bureau of the Civil Aeronautics Board.
BY THE BOARD
Secretary
