FADEC and fuel control system

[shariff001]

I will like some one to please shed more light on how the FADEC control system on a piston engine airplane and possibly possibly explain how it functions in adjusting the strength of air-fuel mixture delivered to each cylinder in a multi-cylinder piston engine airplane? Thanks.
Shariff

 

[enginebob]

Full Authority Digital Engine Control,
don't know to many specifics on it.
But kinda operates similar to the electronic controls for automobiles. But of course taking into consideration the flight requirements. Lycoming system is called EPiC.

 

[DenisNA]

There are serious differencies between the requirements for fuel metering in automotive and aircraft piston engines. The car engine use feedback from oxygen sensor (Lambda probe) in the exhaust to keep the air/fuel mixture close to the stoichiometric ratio. This is necessary for effective operation of catalyst. In fact such fuel control results in 5-10%loss of available power and similar increase in fuel consumption.

Oxygen sensor is extremely unreliable component, and it is totally unsuitable for leaded fuel like AVGAS.

Therefore aero engine injection control can use only EGT sensors to monitor mixture. Actually this is better solution and it is possible to implement individual control for each cylinder for wide range of mixture settings. Indeed the control algorithm is quite complex.
It is this technology currently employed in Aerosance FADEC system.

Nevertheless the conventional mechanical fuel injection used in Lycoming and Continental piston engines provide excellent results, and the mixture is fine adjusted by pilot, who is always wiser controller than any microprocessor.

 

[enginebob]

Agreed, that is why I used SIMILAR. Which means a computer that is compairing information from feed back devices, to adjust the fuel ratio and requirements for a given load and speed. It was a quick and simple explanation.