47-33-02\tDOUGLAS: (Was Mandatory Note 14 of AD-618-3, Supplement 2; and Mandatory Note 15 of AD-669-3, Supplement 2.) Applies to All DC3 Series Aircraft. \n\nTo be accomplished not later than the first engine change after September 1, 1947, but in any event not later than December 1, 1947. \n\nIn order to preclude cowl flap hydraulic line failures and possible subsequent fires, replace grommets and lines forward of the firewall with AN 833-4 elbows and AN 924-4 nuts, or equivalent, and new fire resistant flexible hose assemblies of proper length.