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Old 05-13-2010, 07:02 AM
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ryan1234
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Joined APC: Jun 2008
Position: USAF
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Default Cessna 421B Fuel System

Does anyone have any useful information/tips for the 421B and specifically the fuel system. (Which looks like the engineer had a seizure when drawing the schematics)...gotta ferry one soon.

I'm pretty familiar with the 421C...

Here's what I understand so far:

"There are a total of six fuel tanks. The tip tanks are the main tanks, 300 pounds of fuel in each. The internal wing tanks are the auxiliary tanks, 290 pounds of fuel in each. Lastly, there were the wing locker tanks that are situated behind the engines. These each carried about 156 pounds of fuel. Take offs and landings are performed using the main (tip) tanks. The reasoning behind this was that there were emergency back-up pumps in those tanks so that in the event of an engine-driven pump failure these electrically-driven pumps would kick in. There are switches that are placed in the "armed" position for takeoffs and landings that allow this transfer of pumps to take place automatically in an emergency situation."



"After the main (tip) tanks are drawn down to half-full, the engines would be switched to draw fuel off of the auxiliary (wing) tanks. Because of the fuel system design, the fuel pumps deliver more fuel to the regulators than is necessary. This excess fuel is returned to the main (tip) tanks, not, as you would think, the auxiliary (wing) tanks. By the time the wing tanks are completely drawn down, the main (tip) tanks will be full again from this excess return. At this time, the main tanks are once again selected as a fuel source. Once the mains are once again drawn down, the fuel from the wing locker tanks can be utilized. This fuel is not directly available to the engines. It can only be transferred by electric pumps to the main tanks. By the time the fuel from the wing locker tanks is fully transferred the mains are full once again and all other tanks are now near-empty."


Does this sound about right?

Feel free to give any advice/tips about the B model
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