FADEC is much more than just controlling mixture. that system is measuring,
monitoring and governing a whole lot of parameters. compared to a human
operating a few levers, FADEC can set all these parameters in a way so the
engine/propeller-combination operates much closer to its optimum.

also, today's engines can only be that economic because of the electronic
system. as an example, fuel injection varies in injection time and the
amount of fuel injected, depending on RPMs, power setting, flow of the mass
of air through the manifold (not just the air pressure in there) and
probably a few more. you cannot achieve this by mechanical or even maunual
solutions.



uli






Morgans wrote:


A properly leaned engine at cruise, with well matched injectors, will have
all of the cylinders humming happily along at the most efficient setting,
and lowest fuel flow. FADEC can not improve on that much, if any.

But, and it is a big but, think of the settings we run on takeoff, and
landing (in case you have to do a go-around) and of the time you are at
idle, or low power on the ground. You are running much richer than need
be,
and not as lean as FADEC would have things set. On the average, us
setting
the mixture is wasting fuel, and is inefficient as compared to FADEC.
FADEC
will reset the mixture many times per second; as often as is needed. That
is something we can never begin to think about doing.