Anyone p

lanning to do for-real, single-pilot IFR needs to plan for the inevitable gyro failure. As too many accidents have shown, relying on your rusty partial panel skills to get you home aint gonna cut it for much more than descending through a thin overcast. For most of us flying behind air-or vacuum-powered gyros, that means at least a backup system or an electric attitude indicator (AI). For those lucky enough to have glass panels, it could mean a battery-powered AI standing by. And it needs to be in your main scan, not on the other side of the panel.

Recently, the market has become flush with choices for backup electric AIs, with a

new entry from the venerable Sigma Tek. Our last look at electric AIs, in the October 2005 Aviation Consumer, concluded that the then-new Sportys offering was the top value, if not the best gyro money can buy.

Since then, Sportys has literally run out of that product and wont be getting any more. That AIs manufacturer, Castleberry, now offers the same gyro under their label, albeit at a higher price than Sportys. In the meantime, Sigma Teks 5000EG has hit the market, joining Mid-Continents 4300 series, which we didnt examine last time.To find out how these two stack up, we gave examples of both to Dave Vorsas of Triumph Instruments in Ft. Lauderdale, Florida and let him poke and prod them to his hearts content. To no ones great surprise, we discovered you get what you pay for.

Sigma Tek 5000EG

The first thing we noticed when taking the 5000EG out of the box was its close resemblance to the companys air-driven gyro. Thats no accident: While many parts of the unit are new, its basic design consists of taking an air-driven AI and converting it to electric power. In this case, that means mounting an electric rotor, along with the wiring and electronics to make it run. Our unit came with a slip/skid indicator-an inclinometer-making it a legal turn-coordinator/turn-and-bank substitute per Advisory Circular AC 91-75.

The second thing we noticed is the 5000EG incorporates a caging mechanism borrowed from higher-end AIs and designed to fit the same case. We found the 5000EGs caging mechanism to be a little notchy. While it wasnt a problem to cage the gyro first time, there was a definite over-center, non-linear feel to it. The Sigma Tek instrument also uses an off-the-shelf AN/MS-standard connector and a plate to cover the missing air/vacuum fitting.

Beyond the caging mechanism, the only other control is the knob adjusting the symbolic airplanes height for the pilots preference. That lean-and-clean look is the way we like it, although the Mid-Continent 4300 has additional front-of-the-instrument distractions-more on that in a moment. The 5000EGs horizon presentation is well-defined, with warm blue, soft medium brown and basic Day-Glo