Chapter 12: Fuel

Question 1

Explain the meaning of an illuminated Main Tank Fuel Pump LOW PRESSURE light.

Answer 1

Fuel pump output pressure is low, or FUEL PUMP switch is OFF.

Note: Two LOW PRESSURE lights illuminated in the same tank illuminate MASTER CAUTION and FUEL system annunciator lights.

Note: One LOW PRESSURE light causes MASTER CAUTION and FUEL system annunciator lights to illuminate on MASTER CAUTION recall.

Question 2

Describe the logic of the blue crossfeed VALVE OPEN light.

Answer 2

Bright:

• Valve in transit, or
• Valve position and CROSSFEED Selector disagree.

Dim:
-Valve is open.

Extinguished:
- Valve is closed.

Question 3

Describe the logic of the blue ENGINE VALVE CLOSED and SPAR VALVE CLOSED lights.

Answer 3

Bright:

• Valve in transit, or
• Valve position and engine start lever or engine fire warning switch in disagreement.

Dim:
-Valve is closed.

Extinguished:
- Valve is open.

Question 4

Describe the meaning of an illuminated fuel FILTER BYPASS light.

Answer 4

Impending fuel filter bypass due to a contaminated filter.

Question 5

Describe the meaning of a fuel quantity LOW alert.

Answer 5

Displayed (amber) –
-fuel quantity less than 2000 lbs. in related main tank.

Note: The fuel quantity digits on tank(s) with low fuel quantity turn amber.

Question 6

Describe the meaning of a fuel CONFIG alert.

Answer 6

Displayed (amber) –

• either engine running
• center fuel tank quantity greater than 1600 lbs.; and both center fuel tank pumps producing low or no Pressure.

Note: The quantity digits on the center tank fuel quantity indicator turn amber.

Question 7

Describe the meaning of a fuel IMBAL alert.

Answer 7

Displayed (amber) –

• main tanks differ by more than 1000 lbs.
• displayed below main tank with lower fuel quantity.
• displayed when airplane is on the ground or in the air.
• inhibited by fuel LOW indication when both indications exist.
• displayed until imbalance is reduced to 200 lbs.

Note: The fuel quantity digits on tank with lower fuel quantity turn amber.

Question 8

Describe two ways to close the spar and engine fuel shutoff valves.

Answer 8

• Place the engine start lever to CUTOFF.
• Pull the engine fire warning switch.

Question 9

Explain how fuel is supplied to the engines with all pumps operating.

Answer 9

• Center tank pumps produce higher pressure than main tank pumps. This ensures that center tank fuel is used before main tank fuel.

Note: When main tank fuel pump pressure is low, each engine can draw fuel from its corresponding main tank through a suction feed line that bypasses the pumps.