Fuel System Flashcards
(33 cards)
How many fuel tanks are there?
Two in each wing, a main tank and collector tank for a total of four tanks for the aircraft.
What is the capacity of the fuel tanks?
406.8 gallons total with 402 gallons usable.
How is the fuel tank vented?
Through inward and outward vents located on the bottom of the wing.
How is pressure kept equal in both tanks?
A cross vent line.
How can fuel gravity feed between the tanks?
A flapper type check valve allows gravity feed between the tanks but does not allow backflow.
Where are the drains?
A single fuel drain is located at the lowest point in each tank.
How do the jet pumps work?
Delivery Ejector and Transfer Ejector
They use motive flow supplied from the low pressure engine driven fuel pump.
How does a jet pump work?
Flow enters the jet pump, its flow is increased as it passes through a venturi which creates low pressure drawing fuel in from the tank through a suction inlet.
What does the transfer jet pump do?
Transfers fuel from the main tank to the collector tank.
What does the delivery jet pump do?
Transfers fuel from the collector tank to the common fuel line.
Describe the electrical fuel pump?
Use?
28 VDC electrical pump located in the bottom of each collector tank.
Provides fuel pressure during engine start and in the event of a low pressure engine driven pump failure.
How is the Electrical Fuel Pump controlled?
A single switch on the overhead panel, either in ON or AUTO.
When does the electrical pump come on if in AUTO?
If the low pressure switch on the air separator senses fuel pressure below 2 PSI, CAWS FUEL PRESS will illuminate.
The boost pumps will remain on for 10 seconds after the pressure rises above 3.5 PSI.
What illuminates when the boost pumps are in operation?
CAWS L/R FUEL PUMP
What illuminates when the air separator senses fuel pressure below 2 PSI?
CAWS FUEL PRESS (boost pumps will cycle on)
How does the automatic fuel balancing system work?
When the EIS senses a difference exceeding 5% between tanks it activates the boost pump in the tank with more fuel, stopping flow from the tank with less fuel.
There is a 1 minute delay in pump activation to avoid excessive operation in turbulence.
What refueling imbalance error can the Automatic Fuel Balancing system handle?
up to 40 gallons/4 LCD segments on the ground.
If the auto balancing system fails how can you manually restore balance.
Placing the boost pump for the side with greater fuel in the ON position.
Describe fuel flow under normal operation from the Wing Tank through the Firewall Shutoff.
- Wing Tank
- Transfer Ejector Pump
- Collector Tank
- Delivery Ejector Pump
- Common Manifold
- Maintenance Shutoff
- Fuel Filter (or bypass)
- Air Separator, Fuel LP switch
- Firewall Shutoff
Describe fuel flow under normal conditions from Firewall Shutoff to Fuel Nozzles.
- Firewall/Cockpit shutoff.
- LP Engine Driven Pump (or internal bypass)
- Fuel/Oil Heat Exchanger
- HP Engine Driven Pump
- Filter (or bypass)
- FCU
- Fuel Flow Transducer
- Fuel Flow Divider and Dump Valve.
- 14 duplex type Fuel Nozzles.
What does the air separator do with removed air?
Passes back to the tanks through the Vent Return Line.
Where is the low fuel pressure switch?
Incorporated in the air separator.
Where is the Low Pressure Engine Driven Fuel Pump and how is it operated?
The LP engine driven fuel pump is mounted on the AGB and is driven by the external oil scavenger pump.
Can fuel still get past the LP Engine Driven Fuel Pump if it fails or is not on yet?
Yes, it has an integral bypass that allows fuel under electric boost pump pressure to bypass during start or when the pump fails.
