On and after May 10, 1939 all necessary expenses in connection with the management and operation of projects transferred to the Authority by Executive Order Numbered 7732 of October 27, 1937, as modified by Executive Order Numbered 7839 of March 12, 1938, may be considered as nonadministrative expenses, notwithstanding the provisions of section 712a of title 15, and be paid from the rents received from each transferred project.