Fuel System

Question 1

If low fuel is detected in the left engine fuel feed line, which boost pump activates

Answer 1

Left and Right both come on.

Question 2

How do you manually transfer fuel?

Answer 2

Select the MAN XFLOW AUTO OVERRIDE and then select the L or R XFLOW switchlight for the low side.
“press the light on the light side” The GRAVITY FLOW could also be pressed to allow fuel to freely move between tanks.

Question 3

What is the maximum fuel imbalance allowed for takeoff and in flight, respectively?

Answer 3

300 lbs/800 lbs

Question 4

What maintains fuel balance between the main tanks?

Answer 4

It is automatically controlled by a bi-directional crossflow pump.

Question 5

The bi-directional XFLOW pump turns on and auto XFLOW begins when the fuel imbalance reached how many pounds?

Answer 5

200 pounds

Question 6

How does center tank fuel arrive at the engine/APU

Answer 6

Transfer ejectors send it to the main tanks. Scavenge ejectors send it to the collector tanks. Main ejectors or boost pumps send it to the engines/APU.

Question 7

All fuel tanks can be serviced by utilizing the overwing filler caps.

Answer 7

FALSE.

Question 8

Powered crossflow can be used for takeoff if desired, but gravity crossflow cannot

Answer 8

False. Neither can be on for takeoff.

Question 9

When will the main tank fuel quantity indications on ED2 and the fuel synoptic page turn amber?

Answer 9

Either main tank is less than 600 lbs.
Total fuel is less than 1200 lbs.
Fuel imbalance exceeds 800 lbs.

Question 10

If the bi-directional XFLOW pump fails to turn on when the fuel imbalance reaches 200 lbs, the pilot must select gravity XFLOW to remedy the situation.

Answer 10

FALSE. Can use MAN XFLOW as well.

Question 11

If there is a failure of motive flow, there is no way to get fuel into the collector tanks

Answer 11

FALSE. Gravity feed lines will keep the collector tanks full.

Question 12

The minimum fuel temperature at the engine prior to takeoff is _______. The minimum bulk fuel and freezing temp for Jet A is

Answer 12

+5 deg C

-30 or -40 deg C.

Question 13

How are the fuel tanks vented?

Answer 13

The tanks are vented to atmosphere by two NACA scoop vents on the underside of the wings. and climb vents. The tanks are positively pressurized.

Question 14

What is used to back up the main ejectors to supply fuel to the engines?

Answer 14

Two electric boost pumps

Question 15

If a significant (more than 800 lb) imbalance condition exists between the main tanks, what message will appear on the EICAS?

Answer 15

FUEL IMBALANCE

Question 16

FUEL CAPACITIES

Answer 16

Pressure Fueling
7492/4610/7492. 19594 TOTAL

             OVERWING 7290/7290.    700 7405/7405.    900 (BONUS...Why more in 900?)

Question 17

Describe the fuel quantity gauging system?

Answer 17

A DC type capitance system indicates usable fuel.

Used for ground and in flight with a computer that compensates for pitch and roll.

Question 18

Is there a manual way to check fuel?

Answer 18

yes 5 magnetic level indicators can be check on the exterior of the aircraft two under each wing and one under the fuselage.

Question 19

Is dispatch authorized with the fuel quantity gauging computer inoperative?

Answer 19

no

Question 20

Fuel quantities and pressures

Answer 20

see limitations slide deck

Question 21

Where is the bulk fuel temperature sensor?

Answer 21

in the right wing tank

Question 22

Where does the APU get fuel from?

Answer 22

A dedicated boost pump in the left collector tank

Question 23

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

Answer 23

Yes however it will not start unless the pump is operating

Question 24

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

Answer 24

yes

Question 25

After turning on the boost pumps what do the switch lights look like?

Answer 25

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

Question 26

After starting both engines what do the fuel switchlights look like?

Answer 26

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

Question 27

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

Answer 27

yes

Question 28

How is the fuel warmed to reach 5 degrees or greater?

Answer 28

the fuel / oil heat exchanger

Question 29

Describe the fuel check valve test.

Question 30

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

Answer 30

T transfer ejector from the center tank to the main tanks
S scavenge ejector from main tanks to collector tanks
M main ejectors from collector tanks to engines

Question 31

aside from scavenge ejectors how does fuel enter the collector tanks?

Answer 31

One way flapper valves allow fuel to move by gravity into the collector tank

Question 32

briefly describe the fuel system

Answer 32

one main tank in each wing an auxiliary tank in the center and two collector tanks which feed the engines located in the center tank. A FQGC Fuel Quantity Gauging Computer montiors fuel quantity, balance and temperature. It corrects for any imbalances through the use of a cross flow pump. Motive flow carries fuel from the wings to the engines for combustion

Question 33

Describe how fuel is automatically transferred from the center tanks to the wings

Answer 33

When the wing tank falls below 93 percent the transfer ejectors in the center tank are activated until the main wing tank quantity reaches 97 percent