48-48-02 DOUGLAS: Applies to All DC-6 Aircraft Not Equipped With Steel Vacuum Pump Discharge Lines Aft of the Firewall and Chicago Metal Hose Assemblies From the Oil Separator to the Pesco Pump. \n\n\tTo be accomplished as soon as practicable, but not later than May 1, 1949. \n\n\tIn cases of malfunctioning of vacuum pumps or other vacuum pump system components, fire can occur within the lines and burn through the hose connection into the engine compartment. To prevent such occurrences, replace the present Aeroquip Hose P/N 260-10WD-15 1/2, existing between oil separator and Pesco vacuum pump, with a new Chicago Metal Hose Assembly No. 9273-1. \n\n\t(Douglas Service Bulletin No. 383 covers this same subject.) Also, to prevent fire from entering the zone behind the firewall, replace the dural vacuum pump discharge line, aft of the firewall, with a steel line. \n\n\t(Douglas Service Bulletin DC-6 No. 401 covers this same subject.)