Mailing List lml@lancaironline.net Message #21035
From: Brian & Debi Shannon <wings@theshannons.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: Brent's Reply (Of Men and EFIS)
Date: Thu, 16 Oct 2003 00:41:39 -0400
To: <lml>
Thanks Brent...great reply to my post - now we're getting to the real issue.  Obviously I wasn't really confused, but I'm glad you elaborated on the subject anyway!  I think all of us would advocate further testing of the EFIS units we are interested in.  I am curious about this statement though:
 
<<Having a "Primary" electric gyro may keep you legal but it may not keep you safe.>>
 
Why do you suggest that having an EFIS display (or two on separate busses) and a backup electrical gyro or T&B is any more unsafe than the traditional setup of a vacuum gyro and an electric T&B?  This of course assumes that your exp has a very robust and redundant dual batt/dual alt electrical system with separate busses.  I am a proponent of the all-electric panel and do not beleive that the vacuum backup is any better than dual electric systems...just to add that to the equation.   Are you implying that all the certified and tested Cessnas/Pipers/Diamonds out there will not give you an acceptable level of safety with their traditional setup? 
 
 
Now I digress....
 
BTW, I don't think you are a fool, quite the contrary actually...I just think that having developed the CFS system and having tested it for certification, you're very aware of the risks inherent in using such a system and maybe you focus on them more than the rest of us.  Obviously, you're quite biased towards CFS as it's the only unit out there that's actually been tested.  Who could argue with that if you've got the cash?  But how likely are we to see all or any of the conditions that you tested for?  The military routinely pays extravagant amounts for parts that need to be certified/tested to extreme levels regardless of their intended use, but is it always necessary?  Did we really need the MILSPEC hammer and the MILSPEC toilet?  Many times the answer would be yes but just as often it might be no!  Only the individual builder/pilot can say for sure how much risk he/she is willing to accept and how much the perceived benefit of EFIS really is to them.  
 
I will be very happy if my CFS EFIS survives that lightning strike, but if it's not my lucky day and my fiberglass tail gets melted off in the process.... then it may not matter to me much anymore that my EFIS is telling me I'm upside down headed toward the ground at 300 knots.  There are many systems on our planes that are NOT redundant and will cause certain death if failure occurs; yet we don't worry about them very often.  I think that even some of the untested EFIS units out there may be more reliable than my Lycoming up front!  Will I die if my engine quits?  Not necessarily, but it's possible.  Will I die if my EFIS quits?  Not necessarily, but again, it's certainly possible given the right circumstances.  How much training has the pilot had.  As for me I have thousands of hours of instrument training on steam gauges and plenty of partial panel, so I feel relatively confident...BUT you (or I) could always be led astray by the partial attitude failure or the display of incorrect or partial data (despite all the best training in the world).  There is a first-hand account by a shuttle astronaut crew who experienced an unplanned attitude gyro failure during a landing scenario practice sim.  The only malfunction was in the attitude indicator and it was simply displaying incorrect attitude information.  You guessed it.  They got themselves into an unrecoverable situation before they realized what the problem was...good thing it was only the sim.
 
The Airbus that crashed  last year due to the "rudder swap" also comes to mind, speaking of the inherent risk in flying.  No amount of testing will prevent you from crashing if your vertical stab falls off. 
 
Would you agree that many of the less severe problems will eventually be found and fixed on the "untested" units?  Barring a lawsuit that puts the company outof business, I tend to think that most problems will eventually surface.  If you fly IMC with your "untested" unit before this and before you have complete faith in it and before there is an acceptable amount of flight experience with it, then you're asking for trouble, IMHO.   I don't know the numbers but I vaguely recall from one of my CRM classes that most accidents are caused by pilot error, not aircraft malfunctions....maybe this will change in the future if planes start crashing due to EFIS problems.
 
But compared to the other risks that we live with every day, how does this risk stack up?  That's the question we need to answer before we go spend a year's worth of pay on an EFIS system.   Yes I know for some out there it may only be a few days/weeks worth but for the rest of us (gov't employees) it's a lot of $$$!  I would never intentionally put my family (or yours or Brent's for that matter) at risk for a few dollars, but the risk here needs to be defined and compared to other risks that we blindly accept each time we raise the gear handle.
 
Don't worry Brent - I won't be flying my plane for a long time...plenty of time to find some of those problems.  So you can still go outside and enjoy the mountains or whatever!  When I do start flying though, watch out because I know exactly who I want to put my EFIS through it's paces...I'm heading straight for Coeur d'Alene and your little strip! 
 
Regards,
     Brian Shannon
 
 
 
 
 
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