Fuel System Flashcards
How many pounds of useable fuel does the single-point refueling system provide?
3906 LBS
How many pounds of useable fuel does the single point refueling system provide for the right system and the left system?
1990 lbs in the right system
1916 pounds in the left system
How many pounds of “over-the-top” is available for useable fuel?
3866 lbs
If your aircraft is being filled using over-the-top fueling, which side must be fueled first and why?
The left side to prevent the airplane sitting on its tail
Where is all fuel carried in the T38?
It is carried in five fuel cells, all of which is carried in the fuselage, aft of the cockpit and forward of the engines
What does the left fuel system consist of?
It consist of two dorsal cells and the forward fuselage cell, these cells normally supply the left engine
Does the left fuel system refer to its physical locaiton of the components that it supplies?
To the components it supplies
What fuel cells comprise the right fuel system?
The center and aft fuselage cells
What components of the T38 does the right fuel system service?
They supply fuel to the right engine
How does each of the fuel cells vent?
They all vent overboard through a common vent located in the vertical tail just above the rudder.
What prevents the loss of fuel due ot aircraft attitude and ambient temperatures?
Check valves located within the fuel system
What does the vent system pressure relief valve do?
It allows fuel to vent overboard in the event of thermal expansion
How is fuel capacity determined?
The capacitance system uses the dielectric properites of fuel. As the quantity of fuel varies, the total electrical capacitance varies in proporiton. This proportion determing the amount of fuel remaining.
Does the fuel system compensate for changes in fuel density?
Yes
How many capacitance probes are in the fuel cells?
7
Does the EED display total fuel or the useable fuel?
Useable fuel
When does the FUEL LOW light come on?
It illuminates after a 7.5 second delay when either fuel quanitity indicator reads below 250 pounds
Does the FUEL LOW light give a warning of actual fuel level or of the fuel quantity indicator reading?
The fuel qunaitity indicator reading.
If you lose the fuel quantity indicator reading, how does that affect the warning system?
Losing the indicator will result in the loss of the warning system.
What are three ways that you will lose the FUEL LOW warning system?
- Fuel Quantity Indicator Fails
- The AC power that energizes the indicator/sensor fails
- DC-Powered EED fails
What is the fuel boost pump powered by?
The AC system
Where are the fuel boost pumps located?
They are located at the low point in each of the fuel systems
What is each boost pump enclosed in and why?
An inverted flight chamber, the inverted flight chamber traps enough fuel to sustain inverted flight (zero G or less) for short periods of time.
Until what altitude should gravity feeding fuel provide sufficient fuel flow to maintain MAX?
Until what altitude is this gravity feeding guaranteed?
At what altitude have flameouts occurred when gravity feeding?
25,000
Gravity feeding is only guaranteed to 6,000 ft and flameouts have occurred as low as 7,000.
What portion of the fuel system causes the engines to shut down when the throttles are placed in the cutoff position?
As fuel leaves a boost pump, it passes through a DC (left essential bus) electrically operated shutoff valve. When the throttles are placed in the cutoff position, the respective shutoff valve closes, halting fuel flow.
What are the two ways to activate the fuel shutoff valves?
- Placing the throttles in the cutoff positon
2. Placing the fuel shutoff switch into CLOSED
What indication is given if the fuel filter was bypassed?
A small red indicator extends on the underside of the aircraft
When will the fuel pressure caution lights determine if the malfunction is a boost pump failure only?
- The crossfeed is off
- Fuel Shutoff Valve is Norm
- Throttle is out of off
What is an indication of a possible fuel leak rather than a boost pump failure
Th Fuel Press light illuminated with the crossfeed ON
What is the crossfeed system genreally used to do?
Correct a fuel imablance of 200 pounds or more
When crossfeeding, how does it balance the fuel load?
It allows you to control which fuel system you are using. It does not transfer fuel from one system to another
When operating with only one engine, what is the operating engine fueled by?
It is fueled by the system with the stronger boost pump
What 5 conditions should you not crossfeed under?
- Boost pump failure
- Fuel quantity indicator malfunction
- Fuel leak
- Two engines and low altitude
- Two engines and low fuel
For both the left and right FF indicators to operate normally, what is required?
DC power from the left essential DC BUS.
What are the FF limits in MIL power?
2100-2700
Is fuel flowing displayed when using afterburner?
No
Before engine start, with external or battery power applied, what should the EED FF indicators read?
They should read no higher than 60 PPH. If a higher indication is present, it may be the result of an EED failure or fuel transmitter failure
What are the two fuel systems connected by?
They are interconnected by a DC operated crossfeed valve.
What are some “common” situations you would turn the crossfeed switch on?
- ex) To use fuel from both systems to supply one engine
- ex) To operate both engines on fuel from one system under boost pump pressure
Within how many pounds should you keep the fuel systems within eachother?
200 lbs
Below what fuel weight in either system does the boost pump reduce its effectiveness (and how much is it reduced by)?
Below 650 pounds of fuel, the surface of the fuel falls below the fuel boost pump upper inlet and the boost pump output is reduced by approximately 40%.
When the FUEL LOW caution light is illuminated, what should you do with your nose position and why?
Establish a slightly nose-up flight attitude to ensure maximum usable fuel from both systems. This attitude is necessary to preculde uncovering the fuel boost pump inlets.
What may happen if the fuel boost pump inlets are uncovered?
Air may be allowed to enter the fuel supply lines and cause an engine flame out
