Piston Engine Fuel Systems

Question 1

What is gasoline?

Answer 1

Petrol.

Question 2

What is the carbon and hydrogen make-up of avgas?

Answer 2

85% carbon and 15% hydrogen.

Question 3

Avgas is a good antiknock. What does anti knock mean?

Answer 3

Anti - detonation.

Question 4

What does the octane value of fuel mean?

Answer 4

Temperature at which it detonates.

Question 5

Avgas is very volatile. What dies volatile mean in terms of flash point?

Answer 5

Low flash point.

Question 6

What is the flash point of avgas compared to jet fuel?

Answer 6

-20 to 37.

Question 7

What is the specific gravity of avgas at 15 degrees?

Answer 7

0.72.

Question 8

What colour is Avgas 100 LL?

Answer 8

Blue.

Question 9

What colour is Avgas 100?

Answer 9

Green.

Question 10

What colour is Avgas 80?

Answer 10

Red.

Question 11

What three things do a sample of fuel need to be before flight?

Answer 11

1) clean/bright 2) free of sediment 3) no water.

Question 12

What is the maximum allowed water content in fuel?

Answer 12

30ppm.

Question 13

Why do two detonations (small explosion) cause mechanical shock?

Answer 13

High pressure.

Question 14

What are the three causes of detonation within an engine?

Answer 14

1) poor knockback fuel 2) incorrect mixture 3) high temperature.

Question 15

Whats can cause the fuel to ignite in the cylinder of a piston aircraft before the top dead centre position?

Answer 15

Hotspot (carbon).

Question 16

What are the three causes of pre ignition?

Answer 16

1) Hotspot 2) ignition malfunction 3) high temperature

Question 17

What mixture ratio do we use for takeoff in a piston aircraft?

Answer 17

Rich.

Question 18

What mixture ratio would be used at cruise for a piston aircraft?

Answer 18

Lean.

Question 19

What is the chemical correct mixture ratio for a piston aircraft?

Answer 19

15:1.

Question 20

What three reasons explain why we need lead in our engines?

Answer 20

Lubrication - strengthen valve seats - cooler

Question 21

Consider a climb with a piston engine aeroplane. What will happen to the fuel flow if the pilot maintains the same power setting?

Answer 21

Decreases.

Question 22

The use of too low an octane fuel may cause what?

Answer 22

Detonation.

Question 23

The magneto in a piston engine ignition system is switched off by grounding primary/secondary circuits.

Answer 23

Both.

Question 24

The conditions which can cause detonation in a piston engine are blank map and blank rpm.

Answer 24

High map and low rpm.