12.20.10. Describe the procedures and the precautions to be taken when hand-swinging apropeller to start an engine. 

Procedure
– Pilot at controls.
– Competent person to swing the propellor.
– Swing in a manner that allows the prop swinger to step back as they pull the prop through.

Precautions
– treat the ignition as live even if switched off.
– clear area of obsticles which could possibly trip the swinger.
– no loose clothing etc for swinger.

12.20.8. Explain the purpose and the typical procedure for conducting magneto checks.

Purpose
– to check that both magneto systems are operating correctly
Procedure (before flight)
– Dead cut check at low power. BOTH- L – R – BOTH
Checks that both systems are working before hi-power runup check.
– Magneto check at RPM given in Flight Manual. BOTH – L – Both – R – BOTH. Check RPM drop similar(within limits) for each system.
Procedure (after flight)
– (at idle RPM) BOTH – L – R – OFF – BOTH
to check the the system is dead when turned off.

– dead cut check at low power – 800 – 1000 rpm
– switxh briefly from BOTH – L – R – BOTH
– the engine should not cut as L or R is selected

12.20.6(including . the starter warning light). 

Starter Warning Light (if fitted)
– the starter warning light in the cockpit will glow while the starter is engaged
– should extinguish the moment the pilot releases the starter
– it will remain on if the starter relay “sticks”
– if this happens stop the engine (mixture to IDLE CUT-OFF)

12.20.6. Describe the operation and correct handling of typical ignition/starter switches

– There are two common types of starter switch:
– Rotary key operated in which the key when turned activates the magnetos and then when turned further activated the starter motor.
– Separate magneto switches with a push button starter engagement. This type is normally started with the left (impulse) mag on and the other mag switched on after start.
Starter motors should not be engaged continuously for long periods of time because of heat build up.

12.20.4. State the purpose and principle of an impulse coupling.

Impulse Coupling
– incorporated into one magneto usually the left mag.
– generates a high energy spark and delays or retards the spark timing during initial engine start
– makes it easier initially for the engine to fire and gain rpm

12.20.2. Describe the principal features of a typical magneto ignition system (dual,independent, engine-driven magneto systems with two spark plugs per cylinder). 

Magneto Ignition System
– Magneto is self contained electrical generator which provides high tension electrical current for the spark plugs
– sparks generated by the magnetos are distributed at the pre-determined time through high tension electrical leads to the appropriate spark plugs by the distributor which is built into each magneto
– high tension leads are often bound together to form an Ignition Harness

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.