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Date: Mon, 21 Jun 2010 08:20:51 -0400
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From: "Tom Gourley" <tom.gourley@verizon.net>
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Subject: Re: [LML] Re: Legacy Glass Panel Suggestions?
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From a previous post:
"Yes, briefly... they both went black for a few minutes... never found out 
why.  The two EFIS are linked.  I guess it could happen again.  If all 
electrical went, the Garmin still has a couple of hours on its internal 
battery, with its PFD."

One of the great things about building your own airplane is you can put 
whatever equipment you choose in it.  With that freedom comes 
responsibility, and risks.  When considering options for your equipment also 
think through all the potential problem situations you can, then talk to 
other pilots, especially ones with lots of experience, and read accident 
reports.  What can go wrong with your panel in flight?  Well, lots of 
things.  I've built some panels and flown with several pilots, helping them 
check out their panels, and seen surprising things.  Most problems were seen 
in the first 50 hours or so, which you'd expect.  I've seen EFIS displays do 
strange things, even the more expensive ones.  One example was a system with 
synthetic vision that flipped upside-down just before the landing flare. 
Rather disconcerting to suddenly see the runway at the top of the screen and 
the sky at the bottom.  It only did it at certain airports.  I've seen an 
EFIS slowly tumble while in straight and level flight.  It had to be power 
cycled to bring it back. I've seen dual EFIS disagree with each other, even 
when linked together.  On another dual EFIS setup one or both displays would 
randomly reboot.  This was a high end system and was supposed to be fairly 
mature.  Turns out the specific combination of equipment and interconnnects 
used on this plane, while perfectly valid, had not been thoroughly tested by 
the manufacturer.  They fixed it, but it required multiple software updates 
to get it right.

Speaking of software updates, that's something else to beware of.  Even well 
tested panels that have been operating trouble free for hundreds of hours 
can suddenly develop a problem after an update.  It's not uncommon for an 
update to fix one problem but create another one.  Never launch into IFR 
conditions right after loading an update.

Now I'm definitely not saying you shouldn't go with a glass panel; they're 
great.  I love 'em.  Just be aware that losing electrical power isn't the 
only thing you should be concerned about.  Put some serious thought into 
your backup equipment and make sure it will serve your needs if the glass 
ever goes dark; for whatever reason.

Tom Gourley