REFLECTOR:FADEC info

KeithHallsten reflector@tvbf.org
Sat, 20 Dec 2003 16:56:27 -0800


Jim,
It sounds like you've been sucking on lemons.  How 'bout a little Christmas
spirit?!

The FADEC system had to get through the FAA process of sprinkling with holy
water, so they had to come up with a system that kept the pilot's grubby
hands out of the finer points of engine operation, and would be pretty
reliable, if not as efficient as it has the potential to be.  I am still
pretty interested in the potential of fadec, but I'm not overly impressed
with the currently-available implementation.  Unfortunately, once a system
gets certified the cost of getting the FAA's blessing on system revisions is
prohibitive, and you stop amortizing the already-sunk development cost.
Right now there's a limited market for non-certified engine controls, and
that market is pretty diffuse - if everyone would buy the same system there
might be enough of a market to cover the development cost, but that's not
likely to happen.
Keith

----- Original Message ----- 
From: "Jim Sower" <canarder@frontiernet.net>
To: <reflector@tvbf.org>
Sent: Saturday, December 20, 2003 4:31 PM
Subject: Re: REFLECTOR:FADEC info


> <... 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
>
>
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