AGK - Piston Engine Fuel Systems

Question 1

What is AVGAS, and what is its specific gravity?

Answer 1

Aviation gas, and its specific gravity is 0.72 at 15°C.

Question 2

What must fuel contain?

Answer 2

1. It must contain a lot of energy.
2. It must form a vapour.
3. It must burn quickly.

Question 3

What is pre-igntion?

Answer 3

It’s when the ignition of the mixture has sparked before the spark plugs, this is due to hot spots within the cylinder.

Question 4

What is detonation?

Answer 4

Detonation is when the rapid chemical deposition of the mixture, after burning, has begun.

Question 5

How is detonation controlled?

Answer 5

This is done by adding lead to the fuel.

Question 6

What is AVGAS 100LL, and AVGAS 100?

Answer 6

100LL is blue, and low lead. AVGAS 100 is green.

Question 7

What is the AVGAS flame rate in ft and for the spark ignition?

Answer 7

60-80ft/sec, and this is for the spark ignition.

Question 8

What is the AVGAS flame rate in m/s?

Answer 8

AVGAS burns at 18-24m/s, which causes a rise in cylinder pressure.

Question 9

What is the chemically correct Air/Fuel ratio by mass?

Answer 9

The correct Air/Fuel ratio by mass is 15:1

Question 10

What are some causes of Detonation?

Answer 10

1. Poor fuel quality.
2. Incorrect mixture.
3. High engine temperature.

Question 11

What are some causes of Pre-Ignition?

Answer 11

1. Hot spots within the cylinder.
2. Damaged spark plugs.
3. High cylinder temperatures.

Question 12

What is a rich air/fuel mix ratio that’s normally used for takeoffs?

Answer 12

11:1 is the rich ratio.

Question 13

what is the lean air/fuel mix ratio that’s normally used for cruise altitudes?

Answer 13

17:1 is the lean ratio,

Question 14

What does excessively rich mixture cause?

Answer 14

It causes black smoke.