Piston Engine Fuel Systems Flashcards
What is gasoline?
Petrol.
What is the carbon and hydrogen make-up of avgas?
85% carbon and 15% hydrogen.
Avgas is a good antiknock. What does anti knock mean?
Anti - detonation.
What does the octane value of fuel mean?
Temperature at which it detonates.
Avgas is very volatile. What dies volatile mean in terms of flash point?
Low flash point.
What is the flash point of avgas compared to jet fuel?
-20 to 37.
What is the specific gravity of avgas at 15 degrees?
0.72.
What colour is Avgas 100 LL?
Blue.
What colour is Avgas 100?
Green.
What colour is Avgas 80?
Red.
What three things do a sample of fuel need to be before flight?
1) clean/bright 2) free of sediment 3) no water.
What is the maximum allowed water content in fuel?
30ppm.
Why do two detonations (small explosion) cause mechanical shock?
High pressure.
What are the three causes of detonation within an engine?
1) poor knockback fuel 2) incorrect mixture 3) high temperature.
Whats can cause the fuel to ignite in the cylinder of a piston aircraft before the top dead centre position?
Hotspot (carbon).
What are the three causes of pre ignition?
1) Hotspot 2) ignition malfunction 3) high temperature
What mixture ratio do we use for takeoff in a piston aircraft?
Rich.
What mixture ratio would be used at cruise for a piston aircraft?
Lean.
What is the chemical correct mixture ratio for a piston aircraft?
15:1.
What three reasons explain why we need lead in our engines?
Lubrication - strengthen valve seats - cooler
Consider a climb with a piston engine aeroplane. What will happen to the fuel flow if the pilot maintains the same power setting?
Decreases.
The use of too low an octane fuel may cause what?
Detonation.
The magneto in a piston engine ignition system is switched off by grounding primary/secondary circuits.
Both.
The conditions which can cause detonation in a piston engine are blank map and blank rpm.
High map and low rpm.
