Fuel System

Question 1

What fuel tanks does the CRJ have?

Answer 1

1. 1 Center Tank
2. 2 Wing Tanks
3. 2 Collector Tanks

Question 2

Which pumps create motive flow?

Answer 2

Engine driven fuel pumps

Question 3

Which pumps transfer from Center tank to wing tanks?

Answer 3

Transfer Ejectors

Question 4

How does fuel get from wing tanks to collector tanks?

Answer 4

Gravity or scavenge ejectors

Question 5

How does fuel get from collector tanks to engines?

Answer 5

Main ejectors

Question 6

How does motive flow work?

Answer 6

Venturi flow effect created by engine driven fuel pumps

Question 7

What must happen before the fuel system computer can transfer fuel from center tank to wing tanks?

Answer 7

1. One of the two wing tanks drops below 94%.
2. Center tank has fuel
3. Engines are on allowing pumps to be on

Question 8

What does selecting the L FUEL BOOST PUMP do?

Answer 8

Arms the fuel pump

Question 9

When will boost pumps both turn on automatically?

Answer 9

When main ejector pressure is low

Question 10

Why are pressure refueling limits higher than gravity limits?

Answer 10

Gravity fueling does not allow fuel to fill the space above the cap.

Question 11

Which tank cannot be refueled using gravity fueling?

Answer 11

Center tank

Question 12

Describe automatic cross fueling process:

Answer 12

Over 200lb Imbalance:
1. XFLOW pump turns on and indicates direction on EICAS page
2. Turns off when new tank has 50lbs more than tank its pulling from.

Question 13

How would you manually cross flow should auto cross flow fail?

Answer 13

X FLOW OVERRIDE switch on top panel

Question 14

What do you have to be careful with when manually cross flowing?

Answer 14

It will not stop (No protection)

Question 15

What is the maximum fuel imbalance limit and what message would you receive if that limit were exceeded?

Answer 15

FUEL IMBALANCE caution message when over 800lbs (300lb limitation for takeoff)

Question 16

Prior to engine start, why may auto cross flow move fuel to the left wing tank?

Answer 16

APU draws fuel from left side

Question 17

Will the APU shutdown following an APU pump failure?

Answer 17

No, bypass valve allows gearbox pump to take over.

Question 18

What would an “AUTO XFLOW INHIBIT” caution message mean?

Answer 18

Refuel/Defuel computer left on after refueling

Question 19

How is fuel from the wings heated before reaching the engine?

Answer 19

Oil/Fuel heat exchanger

Question 20

What is an MLI and why would you use it?

Answer 20

Magnetic Level Indicator

Used to manually check fuel level if computer fails

Question 21

What prevents fuel from flowing to the outside of the lower wing during a turn?

Answer 21

One way flapper valves

Question 22

What is the restriction when adding fuel to the center tank?

Answer 22

No more than 500 lbs in center tank until at least 4,400 lb in wing tanks.

Question 23

What creates positive pressure in the wing fuel tanks?

Answer 23

NACA scoop

Question 24

You notice after takeoff your center tank fuel quantity increases by 300 lbs. Why would that occur?

Answer 24

Fuel in the fuel lines flows into tank when AoA increases.

Question 25

What would you look for when conducting a FFOD fuel check valve test?

Answer 25

Pumps off and look for PUMP, PUMP, PRESS caution messages.

Question 26

How would you reset the “Fuel Used” value on the fuel synoptic page?

Answer 26

EICAS Menu button