Vacuum or Electric DG, ASI

[Frank_Rizzo]

I puruse lots of sites looking at all my dream planes and recently many of the newer models, especially the from scratch composite designs are moving to all electric panels. Since the beginning of my training I always thought it was a great idea how they divided up the primary instruments between electrics and vacuum/air powered.

Is the conception now that with improved interference shielding and dual alternators/gens that this setup is more reliable? Severe lighting strikes or some crazy X rating of solar flare could render electrical devices inop, or do you think I am just too cautious?

[PhotoPilot]

With today's dual alternator/dual battery systems, you don't have two-source redundancy . . . you have FOUR-source redundancy. For each seperate, isolated electrical system, power can be obtained from either a battery or an alternator. There's very little that could kill four sources of power without warning. If a lightning strike or atmosphereic electrical disturbance was strong enough to knock out an alternator or battery, I'd think it would also be strong enough to knock out your mags, in which case you'd have bigger problems (and a dead vac pump) anyway.

At least in my case, I've got a lot of all-electric flight hours and have never had any issues.

[BrettInLJ]

I think that it has been shown to be more reliable. If you look at the Lancair Columbia 350 for example they have gone with this kind of setup. I think given the issues of vacuum systems, you are more likely to find yourself in a hairy situation with them than the with the electric system. In the G1000 Skyhawk I'm training in now for example, in order to loose the attitude and heading information I would have to be getting no GPS data from either of the two redundant GPS recievers and have no Air Data input. If this happens large red X's appear on the indicators (granted I would have the vacuum driven backup steam gage attitude indicator). Contrast this to what would happend if I lost suction in a traditional system and was rusty on my instrument scan.

If something knocked out all electrical devices and somehow spared the ignition system in a dual electrical system aircraft like the 350, then you would still have your compass, altimeter, and airspeed "steam gauges". It would not be catastrophic and the chance of this happening is a lot less than a vacuum failure.