12. Fuel

Question 1

FUEL TEMP Indicator Source

Answer 1

No.1 tank

Question 2

Center Tank FUEL PUMP LOW PRESSURE Lights

Answer 2

• With switches ON, continuous illumination of one light for 10s illuminates MASTER CAUTION,
• Extinguished when pump output pressure is normal or related switch is OFF

Question 3

FUEL Quantity Indicator Power Source

Answer 3

Available with AC or DC power

Question 4

LOW Alert

Answer 4

• Main tank quantity < 453KG,
• Remains until 567KG,
• Digits and arc turn to amber

Question 5

CONFIG Alert

Answer 5

Illuminates when:
- Either engine running,
- Center tank quantity >726KG,
- Both related pump switches OFF,
- Digits and arc turn to amber

Remains until:
- Both engines shutdown,
- Center tank quantity < 363KG,
- One related pump switch ON

Question 6

IMBAL Alert

Answer 6

• Main tanks differ > 453KG,
• Displayed below Main tank with lower quantity,
• Inhibited by LOW,
• Remains until imbalance reduced to 91KG,
• Digits and arc turn to amber

Question 7

Fuel Measuring Sticks Number

Answer 7

6 for each Main Tanks and 4 for Center Tank

Question 8

FUEL DOOR SWITCH BYPASS

Answer 8

Energizes fueling panel if Refueling Power Control Relay fails

Question 9

NGS Lights

Answer 9

• Nitrogen Generation System,
• GREEN: Operational,
• BLUE: Operational but degraded,
• AMBER: Inoperative,
• No lights means also Inoperative

Question 10

Fuel Check Valves Purpose

Answer 10

• Located throughout the system,
• To ensure proper direction of flow and,
• To prevent transfer of fuel between tanks

Question 11

NGS Operation

Answer 11

• Converts bleed air to nitrogen-enriched air (NEA),
• NEA delivered to Center Tank to reduce flammability,
• Automatically starts after takeoff until short period of taxi in,
• Automatically shut down when:
  1-) Bleed air not available,
  2-) On the ground and not in test mode,
  3-) OEI inflight,
  4-) Fire or smoke detected in the cargo or main deck areas
  5-) Left PACK overheat,
  6-) Center Tank refuelling valve is open

Question 12

Fuel Pumps

Answer 12

• Each tank uses 2 AC powered pumps,
• Cooled and lubricated by fuel passing through the pump,
• Center Tank Pumps produce higher pressure to Center Tank fuel is used before Main Tanks,
• Each Center Tank Pump will automatically shut off, after a short delay, when low output pressure detected

Question 13

Suction Feed

Answer 13

• Each engine can draw fuel from its related Main Tank via suction feed,
• During climb dissolved air released from fuel due to pressure decrease,
• The air may collect in the Suction Feed line and restrict fuel flow,
• Dissolved air eventually deplete after reaching cruise altitude,
• Main Tank Bypass valves may also be used for suction defueling

Question 14

Fuel Crossfeed Power Source

Answer 14

Valve is DC motor operated from the Battery Bus

Question 15

Fuel Shutoff Valves Power Sources

Answer 15

• Spar Fuel SOV located at the engine mounting wing stations,
• DC motor operated from Hot Battery Bus,
• Engine Fuel SOV are fuel actuated, solenoid controlled,
• Powered from the Battery Bus

Question 16

Center Tank Fuel Scavenge Jet Pump

Answer 16

Operates when:
- Main Tank No. 1 FWD switch is ON,
- No.1 Tank quantity about one-half

Question 17

APU Fuel Feed

Answer 17

• When AC pumps operating, supplied from the left side of the fuel manifold,
• If AC pumps are not operating, suction fed from the Main Tank 1

Question 18

Fuel Quantity Indicator Accuracy

Answer 18

Could show higher or lower than the actual fuel quantity up to 2.5%

Question 19

Fuel Tank Capacities

Answer 19

• No. 1 and 2: 3915KG,
• Center: 13066KG,
• Total: 20896,
• Calculated with 0.8029 density