Standby Vacuum?

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?

TIA

What kind of airplanes do you have? I can understand wanting attitude
indication redundancy in a Bonanza, but it's overkill on a Skyhawk.

Do you have redundant attitude gyros? I've seen more of those fail
than dry pumps, never mind wet.

There are two basic approaches - tapping the intake manifold (which
means full throttle is no longer available if you want vacuum), and an
electrically driven backup pump (which adds weight). Decide whether
you want to carry the extra weight around all the time, or whether you
want to limit yourself to partial power when the vacuum fails. Both
systems work.

I think that if you really feel the need for redundancy, the sensible
solution is replacing the T&B with an electric AI.

Michael

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

Michael wrote:

I think that if you really feel the need for redundancy, the sensible
solution is replacing the T&B with an electric AI.

I see that Sporty's is encouraging this option, too, with their electric
AI.

However, doesn't the AI have the potential to tumble in an unusual
attitude? During my IFR training I recall learning that the turn
coordinator will not tumble in an unusual attitude scenario whereas the AI
may. Since recovery from an unusual attitude was taught to me by first
going to the TC, I would be hesitant to replace an instrument so reliable
during a UA.

What say you?

--
Peter
























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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?

TIA

Electric attitude. Vacuum pumps are going away.

Scott Moore wrote:

Electric attitude. Vacuum pumps are going away.

Or electronic AI (ie. solid state; not a gyro).

My club's fleet all have what used to be the precise flight standby vacuum.
It's not bad, but I'd prefer something else.

One important consideration is preflight. Be sure that you follow the
procedure, lest you find yourself in the clouds with no backup and no
awareness that you've no backup.

- Andrew

However, doesn't the AI have the potential to tumble in an unusual
attitude?

You know, I've heard that too. And it sure seems like it could, by
design. Only thing is, I've spent a lot of time teaching unusual
attitudes - and I've never seen it happen. I think you need something
more radical to happen than what we think of as an unusual attitude -
more aerobatic.

I see little chance of that happening with dual AI's, and even less
chance that the average pilot will recover from an aerobatic attitude
partial panel after screwing up enough to get into that mess.

But hey - if you have the panel room, why not keep the electric TC too?

Michael

Michael wrote:

I see little chance of that happening with dual AI's, and even less
chance that the average pilot will recover from an aerobatic attitude
partial panel after screwing up enough to get into that mess.

Interesting that you pointed that out. I was thinking the same thing when
I posed the question but thought that two tumbling AIs would pretty much
guarantee that the pilot would not recover.

But hey - if you have the panel room, why not keep the electric TC too?

My Bonanza has the original TC along with a backup electric AI located to
the left of the TC. However, the electric AI keeps precessing and requires
a reset about four times per hour, which concerns me.

--
Peter
























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I think that if you really feel the need for redundancy, the sensible
solution is replacing the T&B with an electric AI.

I would not remove the T&B. If you add another AI, put it in a nearby
hole, but not the T&B. No other instrument provides turn rate information.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

Airplanes: We have 4 different flavors of PA-28s, six total, plus a Cherokee
Six. The two being upgraded right now are Archers.

Type of Flying: We do not fly a lot of hard IFR, panel space is limited as is
money. Hence, we are not looking at backup horizons, etc. Also, one of the
airplanes will be getting an S-TEC 2/ or 30, which replaces the TC.

Hence, something like the Precise Flight at $400-500 kind of numbers is the
candidate. Possibly an electric pump, though I don't know anything about the cost.

On 8/17/2005 12:41 PM, Mitty wrote the following:
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?

TIA