I don't doubt that, taken in aggregate, experimental avionics experience failure more often than TSO equipment. 

My point was that people who make blanket statements suggesting people should not use experimental equipment at all are drawing the wrong conclusion (and thus giving others bad advice).  That conclusion is using the same gross generalization behaviors as a small child that once burns themselves on the stove and then draws the (incorrect) generalization that "all stoves are bad."  In reality it's not that stoves are bad; simply that you must be careful in their use.

All avionics can be compared to light bulbs.  Cheap ones tend to burn out quicker than expensive ones, but there are always counter-examples (expensive ones going out sooner, cheap ones lasting longer).  The key is, if you have lots of bulbs you won't be in the dark when one fails.

Cheers,

Bill

On 01/-10/-28163 02:59 PM, rwolf99@aol.com wrote:

<<Modern electronic EFIS systems properly installed with backup batteries and internal automatic isolation circuitry are about as fail-proof as a single piece of electronic equipment can get.>>

 

This is not Brent's statement.  Rather, this relates to a suggestion that non-TSOd units should be considered equally reliable as TSOd units, which is something that Brent disagrees with.

 

I think Brent is saying that a device that has successfully passes environmental qualification testing (a TSOd unit) is way less likely to fail than a unit which has not.  His first-hand experience taking an experimental system through this process (Sieera Flight Systems, now Chelton) bears this out.  Such units are most likely more resilient to power fluctuation, temperature extremes, shock and vibration, and even exposure to water.  In this sense, the TSOd unit is more reliable.

 

Having said that, no electronic unit will work without power.  Now you look at internal backup batteries, redundant power sources, multiple generators/alternators, duplicate paths for power, no single point failures, and perhaps other things which are totally separate from the unit itself.  In this sense, the non-TSOd unit and the TSOd unit are equally reliable.

 

Just my two cents...

 

- Rob Wolf

 

p.s. I'm using a vacuum pump and steam gauges.  I don't need no stinkin' electricity.... (But then, if the weather is really bad -- like it's raining -- I stay on the ground.  YMMV)