48-12-02: Nose And Cabin Heater Rework

48-12-02 DOUGLAS: Applies to All C54-DC Serial and the Following DC-4 Airplanes: 42904 Through 42943, 42948 Through 42952, 42982 Through 42996, 43065 Through 43068, 43071, 43072, 43093, 43094, and 43102. \n\n\tTo be accomplished not later than the date established in accordance with the provisions of Special Civil Air Regulation Serial Number SR-329, or any subsequent regulation affecting this compliance date. \n\n\tAs a result of investigation of heater fires, the following changes are to be accomplished in the nose and cabin heater installation: \n\n\t1.\tInstall steel firewall at Station 260 (cabin forward bulkhead) from ceiling level to top of bulkhead to provide isolation between heater compartment and the space between cabin ceiling and top of fuselage. Also, replace present wood panels under heaters with metal panels. \n\n\t(Douglas Service Bulletin DC-4 No. 47 covers this same subject.) \n\n\t2.\t(a)\tInstall all heater control components in airtight steel containers. \n\t\t(b)\tReplace present heater fuel supply pumps with a single electric driven pump attached to No. 2 main fuel tank. \n\n\t\t(c)\tProvide shrouds around all heater fuel line fittings in fuselage. \t \n\n\t\t(d)\tInstall a fire detector and extinguisher system for the nose heater and cabin heaters. \n\n\t(Douglas Service Bulletins DC-4 Nos. 64 and 64 addendum cover this same subject.) \n\n\tIn some cases, operators have obtained approval from FAA Regional Offices for systems which differ in arrangement and detail from the above provisions. Designs which have been separately approved in this manner are considered to meet the intent of this Note. \n\n\tThis supersedes AD 46-39-02.