Standby Vacuum?

On Mon, 22 Aug 2005 18:06:14 -0700, Scott Moore
wrote:
snip
I disagree. A battery backed up electric AI is not cheap, but compared to all of the
components in a full vac system, it is, and its far more reliable. Even HAVING a
current VAC system does not eliminate that cost, since the MTBF for a vac pump is
down below 1000 hours, meaning you are going to have to change it soon in any case.

Mine has a couple thousand on it and is still going strong.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Andrew Gideon wrote:
Michael wrote:

First off, with dual AI's next to each other, I believe that following
a dying AI into an unusual attitude becomes far less likely, and thus
while the chances of recovery from the unusual attitude are reduced
slightly, the chances of encountering it in the first place are reduced
dramatically. Not so with a backup vacuum - you have to engage it.

This is the first of my two major reasons for preferring the backup AI. It
helps with problem detection. A backup vacuum doesn't.

Which is why the Precise Flight standby systems include a low-vacuum
annunciator light.

-cwk.

Roger wrote:
On Mon, 22 Aug 2005 18:06:14 -0700, Scott Moore
wrote:
snip
I disagree. A battery backed up electric AI is not cheap, but compared to all of the
components in a full vac system, it is, and its far more reliable. Even HAVING a
current VAC system does not eliminate that cost, since the MTBF for a vac pump is
down below 1000 hours, meaning you are going to have to change it soon in any case.

Mine has a couple thousand on it and is still going strong.

Do you have a wet pump? I would not fly hard IFR with a dry pump with
much over 500 hours, and I do have a standby vac. The "M" in MTBF means
half of the pumps last longer than that time, but it also means half
lasted less. If the ceilings are 1000' I'm not rolling those dice.

-cwk.

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

I'm of the general opinion that it's fairly difficult to go overboard
on safety equipment, though the C-150 with TCAS that I saw a year back
tripped even my meter.

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

I'd agree with this. I have a 172 with the Precise Flight system that
was installed before I bought it and I certainly like having it. But
it's not really a cheap install and there is a recurring AD (unless
this is eliminated on new units?) so when you add it all in I doubt
it's much cheaper than the electric AI.

-cwk.

Peter wrote:

Didn't PF go bust recently, or was it some dual-vac pump company?

You're probably thinking of Aero-Advantage, which marketed a dual-rotor vacuum
pump. It was recently the subject of an AD requiring removal of installed pumps.
I have one, it will be removed at the next annual in October. Too bad. I think
it was a nice unit, but Aero-Advantage didn't have deep enough pockets to
maintain the certification in the face of reports of short service life in some
installations, IIRC.

Dave

Peter wrote:

Didn't PF go bust recently, or was it some dual-vac pump company?

I did notice this a while ago:

http://www.preciseflight.com/standby.html

I don't know the backstory, however.

- Andrew

Almost for sure they have transferred the product (and the liability) into a
separate corporation with few or no tangible assets. Probably going naked on
liability insurance as well. This keeps the bloodsuckers from the Trial Lawyers
Association away.

Even good, decent people are forced to this kind of thing these days.

On 8/29/2005 12:30 PM, Andrew Gideon wrote the following:
Peter wrote:


Didn't PF go bust recently, or was it some dual-vac pump company?


I did notice this a while ago:

http://www.preciseflight.com/standby.html

I don't know the backstory, however.

- Andrew

Do you have any evidence for this, or is it just your uninformed,
nonthinking prejudiced knee-jerk reaction?

ROFL

On 8/29/2005 9:54 PM, wrote the following:
Do you have any evidence for this, or is it just your uninformed,
nonthinking prejudiced knee-jerk reaction?

Real intelligent. I guess I have my answer.