Backup gyros - which do you trust?

Stefan "stefan"@mus. INVALID .ch wrote in message ...
Darrell wrote:

The presence of two attitude indicators is especially valuable when they
disagree. That disagreement will direct your attention to the needle/ball
and basic flight instruments to help determine which one is correct. With a
single AI you could more easily follow a gyro error without noticing a
difference in the other basic instruments until it was too late.

I don't understand this. Needle/ball is always included in my basic
scan. As a starting point on toubleshooting, they are more reliable than
the AI. Am I the only who knows this?

Stefan

Stefan, You have hit the nail on the head. BRAVO!!!!!!!
Many of the real good instrument pilots know that needle, ball,
airspeed are the three essentials to flying. These are the most
reliable instruments on the panel. Once these are mastered then the
rest of the instruments will just make things easy.
Too many of us have forgotten the basics or have just gotten lazy.
When is the last time you flew a true NDB approach? With loran, GPS,
LOC & glide slopes, and vectoring, insturment flying is not that
difficult.
During an ICC, have your instructor give you a real good partial panel
workout.
It is rare to loose a gyro but it happens. Many pilots have lost
their battle with gravity during IMC because they forgot the basics.
This is especially true after loosing a vac pump or electrical system.
Clay

"Sydney Hoeltzli" wrote in message
...

Those Electric and Vacuum AIs come with a get-your-life-back
guarantee they honestly, really truly, won't tumble, never ever,
no matter what, even if I do? How do I test it, in a non-aerobatic
plane not approved for spins?

Sure they can tumble. And I would agree they would tumble before the turn
coordinator. But certainly they won't tumble at anything less than 60
degrees bank; the whole idea of the two AIs is to stop the spatial
disorientation profile way before you approach anything like an aerobatic
maneuver.

Also I am not saying you have to put the turn coordinator somewhere where
you will get vertigo... just not necessarily in the immediate 6-pack area,
perhaps instead closer to where most airplanes have their CDIs. It will
still be readable if you somehow get rolled nearly inverted by wake
turbulence. And in the far more likely situation of a vacuum failure, you
will be very glad your electric AI is right up there in your primary scan
area.

--
Richard Kaplan, CFII

www.flyimc.com

wrote in message
...


Our Arrow has a backup electric AI on the right side of the panel. It is
turned on whenever I am in or near IMC. I do not include it in my primary
instrument scan, but check it periodically to make sure it is on and
stable.

I think that is a really worrisome location. I just flew last month with a
very experienced instrument student who had a similar arrangement in his
182RG and developed vertigo and nausea while flying partial panel with his
primary AI covered up.. he literally could not manage the plane and asked me
to take over for a while to let him take off the hood and relax.

If you do have the electric AI in that location, it would be helpful for you
to occasionally fly a fairly long cross-country flight with a safety pilot
while you use a hood and cover up the primary AI... that would be helpful to
ensure you are not prone to vertigo from flying with the backup AI alone.


--
Richard Kaplan, CFII

www.flyimc.com

Julian Scarfe wrote:

http://www.dft.gov.uk/stellent/group...cst?n=5232&l=4

tells a similarly chilling story of a Bandeirante that lost one of its two
AIs resulting in a loss of control.

What do you think of the conclusions? They seem to be:
1) prevent AIs from failing
2) since 2 AIs weren't enough to keep the plane upright (combined
with 2 turn and banks, 2 of every other instrument), require
passenger planes to have 3

(agree, chilling)
Sydney

Richard Kaplan wrote:

A vacuum faliure with a gradual spooldown of the AI and DG at vary rates is
a subtle process, very different from having an instructor suddenly cover up
a gyro. You are correct that there is enough redundancy in a typical GA
plane to FLY partial panel; the problem is that there is not enough
information for most pilots to IDENTIFY a partial panel situation before the
situation has become critical.

Richard,

There seem to be a number of instances where the pilot was aware
of the problem -- had described it to ATC and possibly requested
some form of assistance -- had been flying the plane for some time
more or less under control, and then lost it. So the pilot did
identify a partial panel situation before it became critical,
he simply couldn't FLY partial panel.

The accident Julian posted the link for more-or-less seems to
fall into this case, as did a couple of local accidents.

Cheers,
Sydney

"Sydney Hoeltzli" wrote in message
...

There seem to be a number of instances where the pilot was aware
of the problem -- had described it to ATC and possibly requested
some form of assistance -- had been flying the plane for some time

No doubt there will always be crashes we cannot avoid. I am sure there are
people with tip tanks who run out of fuel; that does not mean tip tanks fail
to increase an airplane's range.

The fact is that any sim instructor will tell you many pilots have a
difficult time identifying gradual loss of the vacuum system and that
redundant gyro equipment helps to identify this failure earlier.

--
Richard Kaplan, CFII

www.flyimc.com

On 13-Jul-2003, "Richard Kaplan" wrote:

I think that is a really worrisome location. I just flew last month with
a very experienced instrument student who had a similar arrangement in his
182RG and developed vertigo and nausea while flying partial panel with his
primary AI covered up

Our electric AI isn't THAT far to the right. Actually, it's mounted in the
right-hand radio stack, right above the DME. (Arrows and other Cherokees
from the late 1960s on have a double radio stack. With modern avionics
typically taking up less space, there is often room left over. It is a
simple matter to fashion a "blank" with a 3" instrument hole to fit in this
space, and that places the backup AI within reasonable scan distance for the
pilot.)

-Elliott Drucker

"Sydney Hoeltzli" wrote in message
...
| C J Campbell wrote:
| Newer vacuum AIs have warning flags, dual vacuum pumps, and vacuum
warning
| lights on the annunciator panel. If I had an electric AI and a vacuum AI
and
| they disagreed markedly, I would be suspicious of the one having warning
| lights and flags all over it.
|
| CJ,
|
| How do newer vacuum AIs come with dual vacuum pumps?
|

They come with a new airplane attached to them. Not unlike the $350,000
Cessna ball cap I bought.

Sydney Hoeltzli writes:

We have a "warning flag" on our newer AI. I note that it is really
a low vacuum flag. It doesn't say a thing about how reliably the
instrument itself is operating.

Yup, I had one freeze but the vacuum was fine so it didn't complain.

--kyler

On 14-Jul-2003, "Richard Kaplan" wrote:

Our electric AI isn't THAT far to the right. Actually, it's mounted in
the right-hand radio stack, right above the DME. (Arrows and other
Cherokees from the late 1960s on have a double radio stack. With modern
avionics

OK, that sounds fine... in fact perhaps a good location for others
searching for a location for an electric AI.

Yes, it works for us. Also, it should be an easy and relatively inexpensive
installation (unlike swapping instruments with resultant requirements for
changes in wiring harnesses).

In our plane, this installation also allowed plenty of space to install an
ON/OFF switch next to the electric AI. We leave it off when flying in solid
VFR conditions, with the understanding that this will extend its life. So
far, so good. It's required no maintenance in over 7 yrs/1400 hrs (knock on
wood).

-Elliott Drucker