Fuel System Flashcards
PRESS light illuminated under fuel pumps
Fuel pump output pressure is low
*Inhibited on center pumps if selected OFF
Is fuel jettison ARM switch required to turn NOZZLES ON
Yes
What happens with Jettison ARMED and NOZZLES ON
- The center jettison isolation valves commanded
- The main tank jettison valves commanded
- Fuel jettison nozzle valves commanded
*If center pumps OFF center fuel will not jettison
What happens when the jettison ARM switch is pushed
- Arms the jettison system
- Sets fuel-to-remain to max landing weight
FAULT light on jettison ARM switch
- Jettison system is inoperative
- A fault in the jettison system has occured
Fuel imbalance displays
a solid white pointer displays when
1. Main tanks differ by >500kg
2. Main tanks differ by >100kg with XFEED valve open
What happens if fuel balancing is happening in the wrong direction
Imbalance pointer flashes
What happens when balancing is within 100kg
Imbalance pointer flashes for 5 seconds
How many fuel tanks for useable fuel
Three (R/L/C)
Left tank capacity
31,300kg
Right tank capacity
31,300kg
Center tank capacity
82,900
How many fuel pumps in left tank
Two AC pumps, One DC pump
How many fuel pumps in Right tank
Two AC pumps
How many fuel pumps in Center tank
Two AC pumps
Why are the center tank fuel pumps called override pumps
They have higher output that main tanks to ensure center tank fuel is used first
What happens to center pumps when fuel tank empties
Continuous low pressure operation for 15 seconds causes shutoff
When is low pressure shutoff inhibited for center fuel tank pumps
Fuel jettison
What is the use of the DC fuel pump in the left tank
Automatically operates to provide fuel to the APU when AC power is not available during start
Automatically to assist with left engine relight with no AC power and loss of both engines
Where does fuel in the surge tanks drain to
The associated main tank
How many pumps are required for normal operation
One AC pump for each engine
What is the purpose of the Nitrogen Generation System
Reduce flammability of emptied center tank using nitrogen enriched bleed air
When is the NGS system inhibited
- Engine out operations to preserve bleed air
- E/E compartment cooling OFF
- CARGO FIRE ARM switch pushed
Can the engines operate with no pumps operating
Yes, suction fueling bypasses the pumps.
Reduced effectiveness as altitude increases
