In engine fuel systems for aircraft, it is known to utilize a two-stage pump for delivering fuel to a fuel control. A first boost stage is provided by a centrifugal pump which delivers fluid to a second stage fixed displacement pump, such as a gear pump, with the fuel delivered under pressure from the latter pump to the fuel control. The components are normally sized to deliver adequate fuel under maximum operating conditions. Any fuel not demanded by the fuel control is returned as bypass flow from the fuel control to a location between the centrifugal boost stage and the second stage fixed displacement pump. Some heat is generated within this fuel; however, this is minimal under maximum operating conditions.FORGED STEEL VALVES

When the aircraft engine is idling or set in a descending altitude condition, the total fuel required by the engine is considerably less and there is a resulting high bypass flow from the fuel control, with a rise in temperature of the fuel. The temperature of the fuel may reach 300

2012-01-17

Back