Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Thu, 30 May 2002 20:25:31 -0400
Message-ID: <redirect-1252316@logan.com>
From: RWolf99@aol.com
Subject: Re: Vacuum v all electric
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Been awhile since I posted anything, but I've just had my computer guru tell 
me how to decode those freakin' MIME files and I'm getting caught up with the 
list...

I disagree with the group consensus that all-electric is the only way to go.

Seems to me a lot of airplanes fly pretty well with the traditional vacuum AI 
& DG and the electric turn coordinator.  As I recall, the likelihood of 
crashing due to a failed vacuum system is far, far less than due to running 
out of gas or continued VFR into IMC.  Doesn't runnign out of gas cause 
something like 40% of all crashes?  Continued VFR into IMC another 40%?  How 
many crashes are caused by a vacuum system crapping out?  Some, but not many.

I suppose you hard-IFR-all-the-time guys could benefit from the extra 
complexity of an all-electric system, but now you've got probably ten pounds 
of extra crap and several thousand dollars of extra cost that you drag around 
with you all the time.  Plus, you haven't yet addressed the issue of the gyro 
itself failing -- just it's power source.

I'm a fairly inexperienced IFR pilot -- I may punch through marine layers, 
but if it's really raining I stay on the ground.  I couldn't care less about 
Stormscopes and Strikefinders since in this fiberglass airplane with my 
limited IFR experience I have no business trying to thread my way through 
thunderstorm cells or heavy rain showers.  This is not to say that I'll never 
be in the soup, but the percentage of the time I'll be there is going to be 
pretty small.

So maybe I'm burying my head in the sand by ignoring the likelihood of vacuum 
failure, but maybe not.  In my Cessna the vacuum gauge was way over on the 
other side of the airplane, where I never looked at it.  In my 360 it will be 
right next to the AI where it's plainly visible.  In addition, I'll have a 
low vacuum switch tied into Jim Frantz's annunciator system.  And let's not 
forget my resolution to practice partial panel on a regular basis.

It's all about risk management.  My risks of perishing due to a vacuum 
failure are low since I'm not IFR that much and I'll have warning systems to 
alert me to the vacuum failure.  My risks of not finishing the airplane due 
to extra cost and time to install a dual-redundant electrical system and 
gyros which cost 4-5 times as much as the vacuum ones are significantly 
higher.

If I were to add weight and dollars to the project, I'd make the fuel system 
bulletproof -- not the IFR instrumentation.  But I think I've already done 
that by keeping the relatively simple header tank installation.

Perhaps as I get more IFR experience and begin to feel comfortable in hard 
IFR, plus after I've paid off all the loans, I'll retrofit a dual electric 
system and the high cost electric gyros.  But for now, I'll stay the same as 
99 percent of the aviation fleet with the traditional setup, and take my 
chances.

- Rob Wolf