Fuel

Question 1

Describe the fuel tank venting system.

Answer 1

There are NACA vents and climb vents. The tanks are positively pressurized.

Question 2

Describe the fuel quantity guaging system.

Answer 2

A DC type capacitance system indicates usable fuel.

Question 3

Is the capacitance system calibrated for ground or flight conditions?

Answer 3

Both. In flight the computer compensates for aircraft attitude.

Question 4

Aside from digital readouts, is there any other way to detirmine fuel quantity?

Answer 4

Yes. There are five Magnetic Level Indicators than can manually be checked on the exterior of the aircraft, two under each wing and one under the fuselage.

Question 5

Can raw data from the Magnetic Level Indicators be used to detirmine the fuel level?

Answer 5

No. A conversion chart from the AFM must be used.

Question 6

Is dispatch authorized with the Fuel Quantity Gauging Computer inoperative?

Answer 6

No.

Question 7

What are the tank capacities with pressure refueling vs gravity?

Answer 7

Pressurized: 7,492 in each wing, and 4,610 int he center totalling 19.594.

Unpressurized: 7,290 in each wing totalling 14,580. The center tank cannot be gravity refueled.

Question 8

Where is the bulk temperature sensor?

Answer 8

In the right wing tank.

Question 9

Explain the automatic fuel crossflow system.

Answer 9

The FQGC initiates a crossflow by activating the bi-directional crossflow pump when it detects a fuel imbalance of 200 pounds between the wings. The crossflow will continue to operate until the low wing has 50 pounds more fuel that the wing with the previous higher quanitity.

Question 10

How is fuel manually transfered?

Answer 10

First, press the MAX XFLOW AUTO OVERRIDE switchlight. Then press the L or R XFLOW switchlight on the low side (remember: “press the light on the light side”) to activate the bi-directional crossflow pump. The GRAVITY XFLOW switchlight could also be pressed allowing fuel to freely move from one tank to another. By banking the aircraft or entering a gentle slip, gravity will move the fuel.

Question 11

Where does the APU get fuel from?

Answer 11

A dedicated boost pump in the left collector tank.

Question 12

If the APU boost pump fails will the APU keep running?

Answer 12

Yes, but it will not start unless the pump is operating.

Question 13

Will the main engines start without their respective boost pumps running?

Answer 13

Yes.

Question 14

After turning on the boost pumps, what do the switchlights looks like?

Answer 14

The upper section of the switchlights illuminate “on,” because low pressure is detected in the fuel lines and the pumps begin running.

Question 15

AFter starting both engines, what do the fuel switchlights look like?

Answer 15

The lights extinguish because the pumps enter the standby mode. Motive flow supplies the fuel to the engines.

Question 16

Will both boost pumps turn on if only one of the boost pump switchlights is pressed?

Answer 16

Yes.

Question 17

At what fuel quanitity does the digital fuel readout turn amber?

Answer 17

Less than 1,200 lbs total or less than 600 lbs per wing.

Question 18

What is the maximum fuel imbalance for takeoff and flight?

Answer 18

300 for takeoff, 800 for flight.

Question 19

What is the minimum fuel for execution of a go-around?

Answer 19

600 lbs per wing assuming a maximum of 10º nose up.

Question 20

What is the center fuel tank limitation?

Answer 20

Each wing tank must have a minimum of 4,400 lbs to takeoff with more than 500 lbs in the center tank.

Question 21

What is the bulk fuel freezing temperature for Jet A?

Answer 21

-40º C

Question 22

What is the minimum bulk fuel temperature of Jet A for takeoff?

Answer 22

-30º C

Question 23

What fuel temp is required for takeoff at the engine?

Answer 23

5º C

Question 24

How is the fuel warmed to reach 5º C or greater?

Answer 24

The fuel/oil heat exchanger.

Question 25

What is the maximum fuel imbalance while over wing refueling?

Answer 25

2,500 lbs.

Question 26

Describe the fuel check-valve test.

Answer 26

On the first flight of the day start the left engine first. Turn off both boost pumps and look for 3 amber EICAS messages, L and R BOOST PUMPS, and R FUEL LOW PRESS. This check is accomplished to verify that the one-way check-valve is operating correctly and motive flow fuel is not pressurizing the opposite engine. Upon completion of the first flight, shut down the left engine and turn off both boost pumps. Look for the 3 EICAS messages, L and R BOOST PUMP, and L FUEL LOW PRESS to check the remaining check-valve.

Question 27

Describe the path of fuel from the center tank to the engines.

Answer 27

• Transfer ejector from the center tank to the main tanks.
• Scavenge ejector from the main tanks to the collector tanks.
• Main ejectors from the collector tanks to the engines.

Question 28

Aside from the scavenge ejectors, how does fuel enter the collector tanks?

Answer 28

One way flapper valves allow fuel to move via gravity into the collector tanks.