01/18/23 Fuel Flashcards
Where is the Nitrogen Generation System Operability indicator?
The NGS Operability Indicator is located in the main wheel well adjacent to the APU Fire Control Panel. The Operability Panel provides the Flight Crew with operating status of the NGS.
What do IMBAL, CONFIG, and LOW (amber) lights indicate?
IMBAL - Main Tank fuel quantities differ by more than 1000 lbs for 60 seconds
CONFIG - greater that 1600 Center Tank fuel, both CTR FUEL PUMP switches OFF and either engine is running.
LOW - less than 2000 lbs for 30 seconds
The IMBAL (amber) Alert is displayed when Main Tank fuel quantities differ by greater than 1000 lbs for greater than 60 seconds. It is indicated by:
- IMBAL (amber) displayed below the Main Tank with lower fuel quantity, and
- the digital quantity for the lower fuel quantity is displayed amber The Imbalance alert is inhibited when a LOW indication exists on the respective tank.
The display remains until the imbalance is reduced to 200 lbs.
The Fuel CONFIG (amber) Alert is displayed when:
- Center Tank fuel quantity is greater than 1600 lbs, and
- both CTR FUEL PUMP switches are positioned OFF, and
- either engine is running
It is indicated by:
- CONFIG (amber) displayed below the Center Tank fuel quantity, and
- the digital quantity for the Center Tank displayed amber
The display remains until:
- both engines are shutdown, or
- Center Tank fuel quantity is less than 800 lbs, or
- one CTR FUEL PUMP switch is positioned to ON
The Fuel LOW (amber) Alert is displayed when the respective Main Tank fuel quantity is less than 2000 lbs for greater than 30 seconds. It is indicated by:
- LOW (amber) displayed below the low Main Tank quantity, and
- the digital quantity for the low tank displayed amber The display remains until fuel tank quantity in the respective tank increases to 2500 lbs.
With all pumps operating, which fuel tank is burned first? Why?
Center Tank, difference in fuel pressure output by the center tank pumps
Fuel pump output pressure differential ensures that Center Tank fuel is used before Main Tank fuel, even though all fuel pumps are operating
What causes the Center Tank Fuel Scavenge Jet Pump to activate?
The No. 1 Main Tank Fuel Pump FWD switch On, fuel transfer is initiated when a float valve opens at a Main No. 1 tank quantity below 4500 lbs or less and continues for the remainder of the flight.
With the No. 1 Main Tank Fuel Pump FWD switch ON, the Center Tank Fuel Scavenge Jet Pump operates automatically to transfer any remaining Center Tank fuel to Main Tank No. 1. Fuel transfer is initiated when a float valve in Main Tank No. 1 opens on fuel quantity in the No. 1 tank decreasing to 4500 lbs or less. This allows scavenge transfer into the No. 1 tank from the Center Tank. Once the fuel scavenge process begins, it continues for the remainder of the flight at a rate of 220-450 lbs per hour.
When do the Center Tank Fuel Pumps automatically shut off?
approximately 15 seconds after a continuous LOW PRESSURE signal has been detected, the respective pump automatically shuts off.
With the loss of AC power, how is fuel provided to the engines?
When Main Tank fuel pump pressure is low, each engine can draw fuel from its corresponding Main Tank through a suction feed line that bypasses the pumps.
What is the purpose of the Crossfeed Valve?
interconnects the engine fuel manifolds to enable crossfeeding. Fuel pressure can be provided from a Main Tank with operating fuel pumps to both engines by opening the Crossfeed Valve.
What is indicated by a bright blue Crossfeed VALVE OPEN light?
The Valve is not in it’s commanded position. (In transit, or Open when switch in closed position or Closed when switch in open position)
bright blue when valve is in transit or valve position disagrees with selector position
What does the Engine Start Lever control? What occurs in each position?
The Engine Fuel (High Pressure) Shutoff Valve and the Spar Fuel Shutoff Valves.
IDLE Position - Valves Open
Cutoff Position - Valves Close
What do the ENG VALVE CLOSED (blue) and SPAR VALVE CLOSED (blue) lights indicate?
Bright blue when valves are in transit or don’t agree with switch position
Dim blue when valves are closed
Extinguished when valves are open and commanded open
Which tank can the APU suction feed fuel from?
Main Tank No. 1
If the AC fuel pumps are not operating, fuel is suction fed from Main Tank No. 1.
How is fueling and defueling accomplished?
at the single-point pressure fueling station in the right wing.
