Standby Vacuum?

Mitty wrote:
Our club is looking at upgrading a couple of airplanes to Garmin 430s, etc.

It seems to me that standby vacuum would be a good thing to add, too.

1) Good idea? Do these systems really work?

2) Recommendations on type/brand/model?

- based on manifold vacuum, like Precise Flight: Inexpensive. Requires some
pilot training. Shuttle valve requires eventual maintenance. Even with training,
you might be surprised when you lose vacuum under some flight conditions (like
during a go-around). They work best when descending, stop working as you add power.

- separate electrically driven vacuum pump: heavy and expensive, but reliable.
Seamless operation. Turn it on and interpret all the gauges same as always.

- electrically driven attitude indicator: the models I know about have been
known to have quality problems, short life, frequent repair. Questionable value
if not in your scan (many seem to mount them on the copilot side).

- GPS with a pseudo-panel, like some of the recent Garmins: Might be OK in a
172-class aircraft. For faster and slipperier aircraft, I question whether
current models update fast enough to keep you out of trouble.

- solid-state gyros in a portable device: never seen one of these so I can't
comment, but some people are enthusiastic about them.

Did I miss any categories?

Dave