CRJ CBT #37 FUEL DISTRIBUTION

Question 1

How does the fuel system computer work?

Answer 1

• It is a two channel computer
• Each channel receives discrete signals from the fuel system, AHRS/IRS.
• The computer uses this^ info to calculate the Fuel Wt(Weight) in each tank
• Only one channel is active at any time

Question 2

What does the fuel system computer control?

Answer 2

• Auto refuel
• fuel x-flow
• fuel calc. (calculations)

Question 3

What do scavenge ejector lines do?

Answer 3

They constantly fill the collector tanks from the wing tanks

Question 4

What do Ejectors do?

Answer 4

• used to move fuel from tank to tank and from tank to engine

Question 5

What do trasfer ejector tanks do?

Answer 5

Move fuel from the center tanks to the wing tanks

Question 6

What do Main Ejector lines do?

Answer 6

Move fuel from Collector tanks to engines

Question 7

How is motive flow created?

Answer 7

• Created when high press. (pressure) fuel (motive press.) from EDP is passed through a venturi shaped nozzle
• As fluid is ejected from the nozzle, fluid velocity is increased and a low pressure is created
• Motive fuel is used to provide movement of fuel from the center tank to the wing tanks, wing tanks to collector tanks, collectors to engines

Question 8

What is the purpose of the boost pumps?

Answer 8

The purpose of the two DC powered pumps is to backup the main ejectors by providing an alternate method of supplying fuel to the engines

Used for STARTING

Question 9

How does the pilot start the boost pumps?

Answer 9

When the pilot presses either fuel pump switchlight, both L and R boost pumps will start

Question 10

Where are Fuel Shutoff Valves (SOV’s) found, and how are they activated?

Answer 10

Found in the MLG (Main Landing Gear) Bay, and located in the fuel feed line, the valves interrupt the supply of fuel to the engines and APU.

Fire pushlights activate SOV

Question 11

How is fuel heated?

Answer 11

Using a fuel/oil heat exchanger.

Question 12

How is fuel filtered?

Answer 12

One fuel filter at each engine, bypass is provided.

Question 13

How does the APU get fuel?

Answer 13

• APU and X-flow(crossflow) systems share the same DC powered x-flow/APU fuel pump and feed
• Both wings feed fuel to APU
• Turn off the fuel feed to APU by pushing the APU FIRE switchlight

Question 14

If the APU fuel feed manifold loses pressure as a result of negative G condition or failure of the APU fuel pump, what is the alternative?

Answer 14

Alternate APU fuel source: Right engine fuel feed manifold via the APU negative gravity check valve supplies the alternate fuel source.