Fuel System

Question 1

What components prevent fuel surging about in flight in tanks?

Answer 1

Baffles

Question 2

What do baffles do?

Answer 2

Prevent fuel surging about in-flight

Question 3

What is higher up? Fuel supply line or fuel sump?

Answer 3

Fuel supply line

Question 4

Why is the fuel supply line not at the bottom of a fuel tank?

Answer 4

To prevent impurities that have collected at the bottom being fed into the engine

Question 5

What is the result of having a fuel supply line not at the very bottom of a fuel tank?

Answer 5

There will always be an unuseable quantity of fuel

Question 6

How is unuseable fuel possible?

Answer 6

Fuel supply line is above the fuel sump

Question 7

What is necessary for atmospheric pressure to be maintained in fuel tanks?

Answer 7

Fuel vents

Question 8

What do fuel vents do?

Answer 8

Retain atmospheric pressure in fuel tanks

Question 9

What would happen if the pressure in a fuel tank reduced?

Answer 9

Reduce the fuel flow rate and cause the tanks to collapse inwards

Question 10

Reduction of the fuel flow rate and tanks collapsing inwards is a result of what?

Answer 10

Reduced pressure in fuel tanks (and insufficient venting)

Question 11

What component alleviates increased pressure in fuel tanks?

Answer 11

Overflow drain

Question 12

What do overflow drains do?

Answer 12

Alleviate excess pressure in fuel tanks

Question 13

When does fuel NOT pass through a carburettor?

Answer 13

When the engine is primed

Question 14

Locking the fuel primer in-flight prevents what?

Answer 14

The cylinders receiving excessive fuel and thus failing due to too-rich a mixture

Question 15

What might cause an engine to receive excessive fuel if the mixture control is set correctly?

Answer 15

Fuel primer is not locked

Question 16

What should be done to the throttle if re-starting the engine due to incorrect fuel selection?

Answer 16

It should be closed to prevent a power surge

Question 17

Why should the throttle be closed when re-starting an engine after incorrect fuel selection?

Answer 17

To prevent a power surge

Question 18

What component purges the fuel lines of vapour?

Answer 18

Fuel boost pumps

Question 19

Fuel boost pumps are also known as?

Answer 19

Auxiliary pumps

Question 20

Auuxiliary pumps are also known as?

Answer 20

Fuel boost pumps

Question 21

What component is used for simple fuel quantity indicators?

Answer 21

A float

Question 22

Electric fuel quantity indicators often use what electrical system?

Answer 22

DC

Question 23

How do electric fuel quantity indicators operate?

Answer 23

Float movement correlates with a variable resistor, changing the current flowing to a gauge
Current alters a magentic field, moving a pointer in the gauge

Question 24

What aspect of a gauge is altered in an electric fuel quantity indicator?

Answer 24

A magnetic field

Question 25

What kind of gauge is often used for fuel pressure indicators?

Answer 25

Bourdon tube gauge

Question 26

What shape is a Bourdon tube gauge?

Answer 26

'C' shape

Question 27

How does a Bourdon tube gauge operate?

Answer 27

Fluid enters the fixed end Pressure change will move the free end of the tube

Question 28

A pressure increase in a Bourdon tube will do what?

Answer 28

Straighten the tube

Question 29

A pressure decrease in a Bourdon tube will do what?

Answer 29

Curve the tube

Question 30

Why is Bourdon tube gauge appropriate for light aircraft fuel systems?

Answer 30

The gauge is in close proximity to the engine

Question 31

What is often used for fuel flow gauges?

Answer 31

Existing pressure gauge that is calibrated to show fuel flow

Question 32

A fuel pressure gauge can also be recalibrated to indicate what?

Answer 32

Fuel flow

Question 33

What is an important facet of fuel flow gauges in fuel-injected systems?

Answer 33

A blocked fuel injector will incorrectly read a higher fuel flow

Question 34

Why does a blocked fuel injector incorrectly read a higher fuel flow in light aircraft systems?

Answer 34

Fuel flow is measured by fuel pressure, so a blockage results in a higher pressure (and thus fuel flow indication)

Question 35

What colour is Kerosene?

Answer 35

Straw

Question 36

What fuel is straw-coloured?

Answer 36

Kerosene

Question 37

100LL AVGAS is what colour?

Answer 37

Blue

Question 38

Blue-coloured fuel is usually what fuel grade?

Answer 38

100LL AVGAS

Question 39

What is added to higher octane fuels to improve anti-detonation qualities?

Answer 39

Lead

Question 40

Why might lead be added to a fuel?

Answer 40

Improve anti-detonation qualities

Question 41

What does a higher rating/grade of a fuel indicate?

Answer 41

Greater anti-detonation qualities

Question 42

What does a higher fuel performance number indicate practically?

Answer 42

The power possible (compared to reference fuel) before a rich mixture would detonate

Question 43

What could occur if using a higher grade fuel than specified?

Answer 43

Spark plug fouling and greater exhaust valve erosion

Question 44

What causes spark plug fouling and greater exhaust valve erosion?

Answer 44

Use of higher grade fuel than speciified

Question 45

Kerosene is also known as what?

Answer 45

Avtur

Question 46

Using motor fuel in an aircraft would cause what?

Answer 46

Lower power output, spark plug fouling and detonation

Question 47

What is vapour lock?

Answer 47

Vaporisation in fuel lines blocks fuel flow

Question 48

What is the term given to vaporisation in fuel lines blocking fuel flow?

Answer 48

Vapour lock

Question 49

What can help minimise fuel tank condensation?

Answer 49

Leaving fuel tanks completely full

Question 50

What is the advantage to leaving fuel tanks overnight completely ful?

Answer 50

Prevents fuel tank condensation