55-20-02 DOUGLAS: Applies to All Douglas DC-7 Aircraft Serial Numbers 44122 to 44146 Inclusive, 44171 to 44174 Inclusive, 44261 to 44289 Inclusive and 44679 to 44684 Inclusive. \n\n\tCompliance required as soon as possible but not later than February 1, 1956. \n\n\tRevising the injection pump timing on the engines creates higher exhaust gas temperatures across the top surface of the wing along the left-hand side of the outboard nacelle. In order to reduce the wing skin temperature, an additional heat shield must be installed between the center and rear spars, and replace the aft section of the existing heat shields between the front and center spars adjacent to the upper left side of the outboard nacelle in the exhaust path area. \n\n\t(Douglas Service Bulletin DC-7 No. 77 dated July 1, 1955, covers this same subject.)