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

Dave Butler wrote:

Did I miss any categories?

Redundant engine driven vacuum pumps.
Quite common on twins and some of the bigger singles. The rub on
singles is having a place to mount the second one.

Ron Natalie wrote:

Redundant engine driven vacuum pumps.
Quite common on twins and some of the bigger singles. The rub on
singles is having a place to mount the second one.

Newer 172s (172R, 172S) even have dual vacuum pumps. That doesn't help
retrofitting, though.

- Andrew

Ron Natalie wrote:
: Redundant engine driven vacuum pumps.
: Quite common on twins and some of the bigger singles. The rub on
: singles is having a place to mount the second one.

Now, even *I* say that's silly for a single. For a twin, sure... since it's likely already in place.
There's still a single point of failure (instrument itself)... An electric AI is more effective. Too bad they're
extra-ridiculously aviation priced.

-Cory
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************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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