Fuel System

Question 1

How many pounds of useable fuel does the single-point refueling system provide?

Answer 1

3906 LBS

Question 2

How many pounds of useable fuel does the single point refueling system provide for the right system and the left system?

Answer 2

1990 lbs in the right system

1916 pounds in the left system

Question 3

How many pounds of “over-the-top” is available for useable fuel?

Answer 3

3866 lbs

Question 4

If your aircraft is being filled using over-the-top fueling, which side must be fueled first and why?

Answer 4

The left side to prevent the airplane sitting on its tail

Question 5

Where is all fuel carried in the T38?

Answer 5

It is carried in five fuel cells, all of which is carried in the fuselage, aft of the cockpit and forward of the engines

Question 6

What does the left fuel system consist of?

Answer 6

It consist of two dorsal cells and the forward fuselage cell, these cells normally supply the left engine

Question 7

Does the left fuel system refer to its physical locaiton of the components that it supplies?

Answer 7

To the components it supplies

Question 8

What fuel cells comprise the right fuel system?

Answer 8

The center and aft fuselage cells

Question 9

What components of the T38 does the right fuel system service?

Answer 9

They supply fuel to the right engine

Question 10

How does each of the fuel cells vent?

Answer 10

They all vent overboard through a common vent located in the vertical tail just above the rudder.

Question 11

What prevents the loss of fuel due ot aircraft attitude and ambient temperatures?

Answer 11

Check valves located within the fuel system

Question 12

What does the vent system pressure relief valve do?

Answer 12

It allows fuel to vent overboard in the event of thermal expansion

Question 13

How is fuel capacity determined?

Answer 13

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.

Question 14

Does the fuel system compensate for changes in fuel density?

Answer 14

Yes

Question 15

How many capacitance probes are in the fuel cells?

Answer 15

7

Question 16

Does the EED display total fuel or the useable fuel?

Answer 16

Useable fuel

Question 17

When does the FUEL LOW light come on?

Answer 17

It illuminates after a 7.5 second delay when either fuel quanitity indicator reads below 250 pounds

Question 18

Does the FUEL LOW light give a warning of actual fuel level or of the fuel quantity indicator reading?

Answer 18

The fuel qunaitity indicator reading.

Question 19

If you lose the fuel quantity indicator reading, how does that affect the warning system?

Answer 19

Losing the indicator will result in the loss of the warning system.

Question 20

What are three ways that you will lose the FUEL LOW warning system?

Answer 20

1. Fuel Quantity Indicator Fails
2. The AC power that energizes the indicator/sensor fails
3. DC-Powered EED fails

Question 21

What is the fuel boost pump powered by?

Answer 21

The AC system

Question 22

Where are the fuel boost pumps located?

Answer 22

They are located at the low point in each of the fuel systems

Question 23

What is each boost pump enclosed in and why?

Answer 23

An inverted flight chamber, the inverted flight chamber traps enough fuel to sustain inverted flight (zero G or less) for short periods of time.

Question 24

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?

Answer 24

25,000

Gravity feeding is only guaranteed to 6,000 ft and flameouts have occurred as low as 7,000.

Question 25

What portion of the fuel system causes the engines to shut down when the throttles are placed in the cutoff position?

Answer 25

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.

Question 26

What are the two ways to activate the fuel shutoff valves?

Answer 26

1. Placing the throttles in the cutoff positon | 2. Placing the fuel shutoff switch into CLOSED

Question 27

What indication is given if the fuel filter was bypassed?

Answer 27

A small red indicator extends on the underside of the aircraft

Question 28

When will the fuel pressure caution lights determine if the malfunction is a boost pump failure only?

Answer 28

1. The crossfeed is off 2. Fuel Shutoff Valve is Norm 3. Throttle is out of off

Question 29

What is an indication of a possible fuel leak rather than a boost pump failure

Answer 29

Th Fuel Press light illuminated with the crossfeed ON

Question 30

What is the crossfeed system genreally used to do?

Answer 30

Correct a fuel imablance of 200 pounds or more

Question 31

When crossfeeding, how does it balance the fuel load?

Answer 31

It allows you to control which fuel system you are using. It does not transfer fuel from one system to another

Question 32

When operating with only one engine, what is the operating engine fueled by?

Answer 32

It is fueled by the system with the stronger boost pump

Question 33

What 5 conditions should you not crossfeed under?

Answer 33

1. Boost pump failure 2. Fuel quantity indicator malfunction 3. Fuel leak 4. Two engines and low altitude 5. Two engines and low fuel

Question 34

For both the left and right FF indicators to operate normally, what is required?

Answer 34

DC power from the left essential DC BUS.

Question 35

What are the FF limits in MIL power?

Answer 35

2100-2700

Question 36

Is fuel flowing displayed when using afterburner?

Answer 36

No

Question 37

Before engine start, with external or battery power applied, what should the EED FF indicators read?

Answer 37

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

Question 38

What are the two fuel systems connected by?

Answer 38

They are interconnected by a DC operated crossfeed valve.

Question 39

What are some “common” situations you would turn the crossfeed switch on?

Answer 39

- 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

Question 40

Within how many pounds should you keep the fuel systems within eachother?

Answer 40

200 lbs

Question 41

Below what fuel weight in either system does the boost pump reduce its effectiveness (and how much is it reduced by)?

Answer 41

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%.

Question 42

When the FUEL LOW caution light is illuminated, what should you do with your nose position and why?

Answer 42

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.

Question 43

What may happen if the fuel boost pump inlets are uncovered?

Answer 43

Air may be allowed to enter the fuel supply lines and cause an engine flame out