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ATLAS 747 Fuel System
Terms in this set (29)
How many fuel tanks do we have and what are their approximate capacities?
•7 fuel tanks (+ horizontal stab for pax airplanes) •1 and 4 mains =13.2k kgs each •2 and 3 mains = 38.1k kgs each •center tank = 52.1k kgs. •2 and 3 Reserves = 4.0k kgs. each •total capacity = 163,042 kgs
What commands fuel valves to open or close and fuel pumps to turn on and off according to fuel management logic?
Fuel system management cards (FSMCs)
Which crossfeed valves are affected by flap extension on the ground?
2 and 3. They are closed by the FSMCs when flaps extend to takeoff position on the ground.
Which fuel pumps are system logic pumps, in other words, commanded to turn on and off by system logic during normal operations?
Override/jettison pumps 2 and 3. They are inhibited from operating when pressure is detected from both CWT override/jettison pumps.
Trace the flow of fuel to the engines when there are 7700 kgs or more fuel in the Center Wing Tank., from blockout.
•Both CWT pump switches should be ON. •X-‐feed valves 2 and 3 close when flaps extended for takeoff •CWT pumps feed engines 1 and 4. •Main pumps 2 and 3 feed their related engine.
Trace the flow of fuel to the engines when there is less than 7700 kgs of fuel in the center wing tank, from blockout.
•Both CWT tank pumps should be off. •X-‐feed valves 2 and 3 close when flaps extended for takeoff. •Override/jettison pumps 2 feed engine 1 •Override/jettison pumps 3 feed engine 4. •Main pumps 2 and 3 feed their related engine.
When do the FSMCs open the reserve transfer valves?
•When main tank 2 or 3 fuel quantity decreases to approximately 18,200 kgs. •Fuel transfers from reserve tanks 2 and 3 to the related main tank.
Under what conditions would fuel automatically transfer from main tanks 1 and 4 to their adjacent tanks 2 and 3?
During fuel jettison, when either main tank 2 or 3 fuel quantity decreases to 9,072 kgs.
Can fuel be manually transferred from any tank to another tank?
•Yes, there is a Main Tank 1 and 4 Transfer Switch on the overhead panel. •Fuel can transfer from the outboard to the inboard main tanks, to approximately 3,200 kgs remaining in each outboard main tank.
State what occurs when you select the Fuel Jettison Switch to A or B.
•Arms the jettison selector. •Displays preselected fuel to remain on EICAS
Describe how the fuel quantity indication changes upon termination of fuel Jettison
•The fuel to remain quantity indication changes from magenta to white. •The fuel to remain quantity flashes for 5 seconds.
What occurs when you push either fuel jettison nozzle valve to ON during the QRH fuel jettison procedure?
•It activates all override/jettison pumps in the tanks containing fuel (pump switches must be on). •The related jettison nozzle valve also opens.
What is the source of fuel for the APU?
•Normally supplied from main tank 2. •When ac power is available, fuel is supplied by main pump 2 aft. •If AC power is not available, a dedicated DC pump in main tank 2 supplies fuel to the APU. •Main pump 3 aft operates to prevent tank to tank transfer and provides fuel if main pump 2 aft fails (with aircraft exceptions)
In general, how would you handle a fuel imbalance situation?
By opening or closing crossfeed valves and turning off and on fuel pump switches (refer to QRH and Supplementary Procedures)
What is the impact on the aircraft of excessive fuel imbalance?
•Adversely affects CG •Aerodynamic drag •Fuel economy
When is an engine on suction feed, and how would you correct a suction feed situation?
•An engine is on suction feed when main tank fuel pressure is low. •Open the appropriate fuel crossfeed valve from a main tank with operating pumps.
Does the suction feed line go through the main tank fuel pumps?
No, the suction feed line bypasses the pumps
A single main tank fuel pump can provide sufficient fuel to how many engines?
•One engine at takeoff thrust •Two engines at cruise thrust.
A single main tank 2 or 3 override/jettison pump can provide sufficient fuel to how many engines?
Two engines at takeoff and cruise conditions
Can the main tank 2 or 3 override/jettison pumps operate when the related Main tank is below 3,200 kgs (standpipe level)
Fuel tank temperature is measured in which tank?
Main tank 1
When does the fuel temperature display on primary EICAS display in amber?
Which aircraft are the only ones with horizontal stabilizer tanks?
How is Center Wing Tank Fuel scavenged?
•CWT fuel is scavenged by 4 jet pumps, two pumping into each main tank 2 and 3. •Scavenge begins when main tank 2 or 3 fuel quantity decreases to approximately 27,200 kgs.
What are the fuel imbalance differences that would generate an EICAS Advisory message?
•1360 between tanks 1 and 4 •2720 between tanks 2 and 3 •2720 between inboard and outboard tanks after FUEL TANK/ENG
When correcting a fuel imbalance condition, when would you expect the associated EICAS Advisory IMBAL message to no longer display?
When the difference is less than 450 kgs
What does a Crossfeed Valve ON, with the bar visible, indication mean for Crossfeed Valve Switches 2 and 3?
Crossfeed valve open when commanded by system logic
What does a Crossfeed Valve ON, with the bar visible, indication mean for Crossfeed Valve Switches 1 and 4?
The crossfeed valve is open
What does it mean when the main tank 2 and 3 Override (OVRD) Fuel Pump Switches are ON? How about OFF, ON not visible?
•ON - fuel pump operates when commanded by system logic. •OFF (ON not visible) - fuel pump selected OFF.
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