Fuel System (Ch. 2)

Question 1

What type of tanks do we have?

Answer 1

Crashworthy, suction-type with a self sealing main tank.

Question 2

What ways can we refuel?

Answer 2

Pressure, gravity, and HIFR

Question 3

What does the prime/boost pump do?

Answer 3

Primes all fuel lines if prime is lost. Also acts as a boost pump for APU start and operation. Allows fuel to enter all fuel lines prior to engine start.

Question 4

What happens when you place the FUEL PUMP switch to APU BOOST? FUEL PRIME?

Answer 4

opens the APU fuel shutoff valve and activates the prime/boost pump. placing the FUEL PUMP switch to FUEL PRIME opens both engine prime shutoff valves and allows individual priming of the engines with the PCL in LOCKOUT.

Question 5

What do the Fuel Selector Levers do?

Answer 5

manually position the fuel selector vales to any one of 3 positions: OFF, DIR, or XFD. OFF position: valves are closed. DIR: valves open, fuel flow for each engine from respective tank XFD: fuel to engine comes from opposite cell.

Question 6

What route does a drop of fuel travel?

Answer 6

Drawn by engine-driven fuel boost pump and pumped through a filter to the HMU high pressure pump, Oil/fuel head exchanger, ODV, then to the Engine.

Question 7

Main tank capacity

Answer 7

590 useable gallons (4,012 pounds)

Question 8

Main cells’ interconnect level

Answer 8

270-600 pounds per side

Question 9

External fuel tank capacity?

Answer 9

120 gallons per tank.

Question 10

How fuel level is measured in the AUX tank?

Answer 10

internally monitored by a single gauge prove. a low-level thermistor sensor that is exposed only when the tank is empty, then sends signal to the FMCP.

Question 11

PUMP/VALVE FAIL

VS.

AUX FUEL XFER FAULT

Answer 11

• PUMP/VALVE FAIL:
  
  • when a single pump or valve fails.
  • the alternate pump or valve will supply fuel xfer capabilities
• AUX FUEL XFER FAULT
  
  • total failure of dual transfer/shutoff valves, dual tansfer pumps, or FMCP logic.
  • manual fuel transfer mode must be used it auto mode fails.

Question 12

During tranfer, if one cell fills faster, monitor. If difference between cells, stop transfering before right cell is full (______ lbs)

Answer 12

1700 lbs

Question 13

Do not initiate unmonitored man fuel xfer to main tanks from aux until main tank is below ____ lbs.

Answer 13

3200 lbs

Question 14

when main fuel tank has decreased by ___ lbs, check manual tansfer.

Answer 14

300 lbs

Question 15

Aux tank considerations for jettison

Answer 15

• emergency jettison of external tanks via ALL STORE JETT pushbutton is inhibited when less than 40 gal (272 lbs) remain.
• SEL JETT must be used to jettison when less than that amount remains.
• fuel gauge is in 50 lb increments. if 300 lbs. or less use SEL JETT.

Question 16

when in auto transfer mode, when will fuel transfer from aux to main tanks?

Answer 16

when main fuel tank fuel level depletes to approximately 2,640 pounds.

Question 17

fuel tank refill sequence?

Answer 17

• main tank
• right external
• left external

**during fuel xfer, sequence is opposite.

Question 18

Fuel Quantity System Operations

Answer 18

• probe in each cell. capacitance type sensor (measures weight of fuel in each tank)
• fuel quantity digital readouts are separate. (goes to MD and FD.)