(Robert M. Gary) wrote in message om...
My Sigma Tek attitude indicator is going South and after one failed
attempt to overhaul it I'm not excited to sent it elsewhere and try
again. It looks like I can buy a new TSO RC Allen for about $100 more
than overhauling my Sigma Tek. Is there any reason this isn't a no
brainer? Why would anyone overhaul a Sigma Tek when they could just
get a new unit? Is the Sigma Tek somehow a better unit?

You didn't specify, but I assume you're dealing with a vacuum driven
unit. The RC Allen electric artificial horizons are lousy, but the
vacuum units are probably good. I had an RC Allen unit in my motor
glider and, engine on, it would start precessing in 5-10 minutes.
Admittedly, my engine (Rotax 914) operates at a much higher rpm
(4800-5800) than the unit is used to, so it may have been somewhat a
function of that.

Engine off, it was fine. Until ... it went south after a few years.
Overhauled it for over $1k -- a new one was a little under $2k -- and
that failed within six months. To be fair to RC Allen, I've heard that
most "low priced" (under $5k) electric AH's are not that good. If you
have a vacuum driven one, be glad!

BTW, other owners of the same motor glider have had similar comments
on the unit, so it isn't just my bad luck.

Martin