REFLECTOR:FADEC info

Jim Sower reflector@tvbf.org
Sat, 20 Dec 2003 18:31:34 -0600


<... safe to say that (probably) all of the gotcha scenarios have been addressed ...>
That's comforting.  I had hoped that my questions were specific enough to warrant
specific answers.  I think it would be interesting to know, if EGTs were driving fuel
delivery, how they address failure modes such as gradual deterioration (inaccurate
output) of the probes and how one might go about distinguishing between a
deteriorating EGT probe and a deteriorating something else (like cylinder) that has a
similar effect on EGT.

But then again, my questions were somewhat rhetorical.  I am much more interested in
auto conversions for a variety of reasons not least of which is that I am not in a
position to spend what FADEC costs.  Seems to me that spending all those thousands of
$ to put a "modern" face on an anachronistic Lyc is an exercise in trying to make a
silk purse out of a sow's ear.

Will it be as reliable and accurate as late model automotive fuel controls? ... Jim S.

Wayne Lanza wrote:

> Hi Jim,
>   If you haven't been made aware of the Aerosance web site - here ya
> go...
> I worked closely for a week with the designers of the system while
> installing
> the Continental FADEC system in Velocity's XL Dash 5 demonstrator
> aircraft.
> They have designed many failure mode operations into the system, safe to
> say that (probably) all of the gotcha scenarios have been addressed.
>
> Have a Great Holiday,
> Wayne Lanza
> Composite Design
>
> goto the Aerosance web page at - http://www.FADEC.com
> ________________________________________________________________
>
> On Thursday, December 18, 2003, at 11:16 PM, Jim Sower wrote:
>
> > I need some help with some specifics on how FADEC works.
> > <... FADEC system meters the fuel-air mixture to ... power ... 100
> > degrees Rich of
> > peak ... cruise ... 100 degrees Lean of peak ...>
> >
> > Is it safe to assume that this FADEC feature is driven by EGT sensors?
> >
> > Is it further safe to assume that FADEC varies fuel delivery from one
> > cylinder to
> > another according to individual EGTs (which of course are caused by
> > uneven air
> > delivery through the non symmetric intake runners)?
> >
> > IIRC, EGT probes tend to fail by degrees, giving increasingly
> > erroneous readings for a
> > while until they quit altogether.  How does FADEC [allege?] to deal
> > with partial
> > failures of EGT probe?  Total failure?
> >
> > Inquiring minds need to know .... Jim S.
>
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--
Jim Sower
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T