12.18. Exhaust System

12.18.6. Describe the possible sources, indications and associated danger of carbon monoxide gas. 

Sources
– can enter cabin through ventilation/heating system. Particularly if ther are any leaks in the exhaust pipe where it passes through any muff used to get air heated by the exhaust pipe for use in the heater,
– exhaust fumes drawn in from outside if the system exits in the wrong place or is damaged.
Indications
– CO is odourless and colourless, but other exhaust gases can sometimes be detected by smell. If you can smell exhaust gas then CO is almost certainly there too.
– use of CO detectors inside all cabins fitted with an exhaust manifold heater
Dangers
– inhalation can impair judgement, leading to loss of consciousness then death

12.18.4. Explain the importance of proper sealing of the exhaust manifold.

– Exhaust gases are very toxic and for this reason it is important that the system is free from leaks and exits in a position from which the gases will not enter the acabin of the aircraft.

12.18.2. Describe the function of the exhaust manifold.

The exhaust manifold is a system of tubes (normally steel) which take the exhaust gases from the exhaust port to an outlet clear of the aircraft.

12.16. Fuel

The hydrocarbon product burned to provide power in an internal combustion engine.

12.16.8. State the common fuel contaminants and the precautions which can be taken to avoid them. 

Most common contaminant is water
– full tanks overnight if in cold weather will minimise condensation
– rust, sand, dust and micro organisms can also cause contamination.
– it is important to filter fuel when refuelling.

12.16.6. State the precautions regarding the use of MOGAS in aero-engines.

– mogas should not be used in an aircraft engine unless its use is authorised.
– more prone to vapour lock, plug fouling and detonation.

12.16.4. Distinguish between the different characteristics of AVGAS, MOGAS andAVTUR (Jet A1). 

AVGAS -(aviation gasoline)
– more leaded than MOGAS – with higher octane / performance rating
– less volatile than MOGAS – safety enhancement (reduces vapour lock tendencies at high altitudes.)
MOGAS – (ordinary motor gasoline)
AVTUR – (aviation turbine fuel)
– straw coloured or clear and smells of kerosene
– not to be used in piston engines

MOGAS in aero-engines
– MOGAS hasn’t the same degree of quality AVGAS which is manufactured to strict quality control standards
– is more volatile than AVGAS
– can cuase vapour locks and fuel starvation in the system
– can cause a lower power output, fouling of the spark plugs and string possibility of detonation

12.16.2. State the common types of fuels and their colour identification.

Different grades of fuels are colour coded

MOGAS
91 = purple
96 – yellow

100LL – Blue
100/130 – Green
115/145 – Purple

12.14. Fuel Injection

A system of introducing fuel to a motor by means other than the pressure drop through a venturi (carburettor)