Slushing Fuel Tanks

FLEXIBLE RUDDER TAB SHAFT WRENCH  |  Volume 2  |  October, 1948
Number 1
MODEL 18 SERVICE NOTES AND CHANGES
Slushing Fuel Tanks

To increase the life of the aluminum fuel tanks used in the Model 18, it is recommended that they be slushed, at the latest, after each 1000 hours of flying time with one of the following compounds:

1. Fuel Tank Slushing Compound No. UL-10310 which may be purchased from the Pittsburgh Plate Glass Co., Paint Division, Milwaukee, Wisconsin
2. Slushing Compound No. 243-35497 which may be purchased from EI DuPont de Nemours and Co, Inc, Finish Division, Chicago 14, Illinois
3. Slushing Compound for Gas Tanks No. TL-652 which may be purchased from W.P. Fuller and Co, 125 N. Los Angeles St, Los Angeles, California

The slushing compound will leave a film on the interior of the fuel tanks which is resistant to gasoline and oil, thereby giving maximum corrosion resistance to the aluminum. The corrosion resistant film is not affected by 100-octane gasoline or aromatic fuel.

Before applying the slushing compound, the tank should be cleaned thoroughly by immersing it in a solution of Oakite No. 61 for 5 to 10 minutes. The temperature of the Oakite bath should be between 170 and 190 deg F. All openings in the tank must be unobstructed to permit the Oakite solution to fill the tank completely and clean all interior surfaces.

The tank should be rinsed thoroughly in hot or cold water after removal from the Oakite No.61 solution and then etched by immersing it in a cold solution of Oakite No.35 for a period of from 3 to 5 minutes. After removing the tank from the etching solution, it should be rinsed thoroughly by immersing it in hot water. Allow the tank to drain completely and dry.

All openings in the tank should then be sealed and approximately 5 gallons of slushing compound should be poured into it. The tank should be rotated on a diagonal axis until it is evident that all interior surfaces have been covered thoroughly with slushing compound. The slushing compound may be drained into a container and saved for future use. The tank should be permitted to drain until all dripping has stopped.

The exterior of the tank should be refinished by painting with one coat of zinc chromate primer and two coats of alumilized lacquer.