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Date: Wed, 21 Aug 2002 11:14:20 -0400
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From: George Braly <gwbraly@gami.com>
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Subject: RE: [LML] PRISM vs FADEC
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Gary,

Excellent message.  

>>Why do it?  The question is probably why do electronics at all, not why do
pulsed injectors.  And I think the only reason is to remove the engine
management workload from the pilot - this includes cold start, hot start,
hot fuel handling and other peripheral advantages.<<

>However, it [PRISM]
can't fix most of the other fuel system weaknesses mentioned above.<<

Well... like I said,  PRISM has the hooks so it *can* make it start better
by managing fuel flow and it can make it start better on hot starts [well...
maybe.. I'm not convinced that even FADEC does that ] - -  but if all that
is stuff that the pilot has to do only once each flight  and then while on
the ground, and not in a critical phase of flight - -  then the reasons for
automating that process  - - become rather less compelling, don't they?

Consider this - -  have you *seen* the FADEC manual ?   Have you read it?
Have you tried to learn the failure modes and indications thereof?  If not,
then you are in for a bit of a surprise.  I was "impressed". 

My impression is that it will take the average pilot many times  longer to
read and understand how to deal with the FADEC fuel system failure modes
than it will take him to brush up on existing cold starts, hot starts, etc.

Flat statement here:  I have been flying high powered injected piston
engines for 36 years.  In the deep south and in the cold north part of the
country and in Canada in winter. I have never yet failed to get one started
promptly - - hot or cold, so long as somebody had not left the master switch
on and run down the battery.  

So what is the big deal that justifies 10 lbs of wire and multiple 50 pin
connectors just to attempt to automate something that is done ONCE on each
flight - - on the ground in a low workload environment ?

Again... is it really worth the failure modes that are interjected into the
system?

You obviously have a lot of experience in this area - - and understand the
issues - - so help me understand this?

Regards,  George