Fuel System

Question 1

PRESS light illuminated under fuel pumps

Answer 1

Fuel pump output pressure is low

*Inhibited on center pumps if selected OFF

Question 2

Is fuel jettison ARM switch required to turn NOZZLES ON

Answer 2

Yes

Question 3

What happens with Jettison ARMED and NOZZLES ON

Answer 3

• 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

Question 4

What happens when the jettison ARM switch is pushed

Answer 4

• Arms the jettison system
• Sets fuel-to-remain to max landing weight

Question 5

FAULT light on jettison ARM switch

Answer 5

• Jettison system is inoperative
• A fault in the jettison system has occured

Question 6

Fuel imbalance displays

Answer 6

a solid white pointer displays when
1. Main tanks differ by >500kg
2. Main tanks differ by >100kg with XFEED valve open

Question 7

What happens if fuel balancing is happening in the wrong direction

Answer 7

Imbalance pointer flashes

Question 8

What happens when balancing is within 100kg

Answer 8

Imbalance pointer flashes for 5 seconds

Question 9

How many fuel tanks for useable fuel

Answer 9

Three (R/L/C)

Question 10

Left tank capacity

Answer 10

31,300kg

Question 11

Right tank capacity

Answer 11

31,300kg

Question 12

Center tank capacity

Answer 12

82,900

Question 13

How many fuel pumps in left tank

Answer 13

Two AC pumps, One DC pump

Question 14

How many fuel pumps in Right tank

Answer 14

Two AC pumps

Question 15

How many fuel pumps in Center tank

Answer 15

Two AC pumps

Question 16

Why are the center tank fuel pumps called override pumps

Answer 16

They have higher output that main tanks to ensure center tank fuel is used first

Question 17

What happens to center pumps when fuel tank empties

Answer 17

Continuous low pressure operation for 15 seconds causes shutoff

Question 18

When is low pressure shutoff inhibited for center fuel tank pumps

Answer 18

Fuel jettison

Question 19

What is the use of the DC fuel pump in the left tank

Answer 19

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

Question 20

Where does fuel in the surge tanks drain to

Answer 20

The associated main tank

Question 21

How many pumps are required for normal operation

Answer 21

One AC pump for each engine

Question 22

What is the purpose of the Nitrogen Generation System

Answer 22

Reduce flammability of emptied center tank using nitrogen enriched bleed air

Question 23

When is the NGS system inhibited

Answer 23

1. Engine out operations to preserve bleed air
2. E/E compartment cooling OFF
3. CARGO FIRE ARM switch pushed

Question 24

Can the engines operate with no pumps operating

Answer 24

Yes, suction fueling bypasses the pumps.

Reduced effectiveness as altitude increases