Chapter 10: Fuel

Question 1

Fuel Tank Composition

Answer 1

• Collector Tank (inboard) and Surge Tank (Outboard)
• Fuel vents connect tanks to Surge Tank and allow venting to external environment
• High pressure relief valve
• Two drain valves collect water in each tank

Question 2

Fuel Quantity Indication

Answer 2

• Sensors measure fuel quantity in each tank
• Independent “low-level” sensor in each tank
• Three (3) magnetic level indicators under each wing

Uncertainty is 2% of indication + 0.75% of tank capacity

Question 3

Fuel Tank Capacity

Answer 3

10,393 lbs per tank (usable), + 75 unusable

Question 4

Fuel Pumps

Answer 4

• Ejector Fuel Pump
• AC Fuel Pump
• Three (3) scavenge ejectors
• DC Fuel Pump (right wing only)

Question 5

AC Fuel Pumps Power Source

Answer 5

AC Pump 1: AC BUS 1

AC Pump 2: AC ESS BUS

Question 6

DC Pump Power Source

Answer 6

DC ESS BUS 2

Question 7

Fuel Imbalance

Answer 7

EICAS message appears at 800 lbs.

Disappears when imbalance is less than 100 lbs.

Question 8

Engine Fuel SOV

Answer 8

Only closed when fire handles are pulled

Question 9

Fuel Level Low Warning

Answer 9

• Indicates 660 lbs. of fuel in respective tank (normal conditions)
• If failure of scavenge pumps, may appear with up to 3,970 lbs. in respective tank
• May appear spuriously with high pitch and/or bank angles
• Engine may flameout if subjected to 15 degrees nose up, uncoordinated flight, or negative loading

Question 10

AC Fuel Pump Logic

Answer 10

Supplies fuel for:

• Onside engine start
• Opposite engine during cross feed
• APU when engine is not running

-Also used as backup if ejector fails