Backup gyros - which do you trust?

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

Big John wrote:
Sidney - just think out of the box
Take AI out of panel leaving hooked up. With power (air/electric)
applied rotate the instrument through all attitudes and see if it
tumbles and where. If it does not meet specs go get your money back.

I don't know, Big John. I still want my turn coordinator left
in my primary scan area. Call me old-fashioned, call me a stick
in the mud, don't call me too late for dinner.

Here's a link to the original post:
http://makeashorterlink.com/?Z27312245

The part about the Safety Board conclusion that an R/C plane was
involved is at the bottom of the post. But the whole post IMO is
very well worth reading.

I fly R/C and doubt if any collision took place. Never heard of it in
AMA magazine and something like that would be a high profile story for
risk of lives and insurance problems.

FWIW, this didn't happen in the US. Australia I think.

Whether or not it was an R/C plane is really a moot point. It
could have easily been a large bird (no feathers or blood though).
IIRC an R/C guy in the vicinity of the collision admitted he
lost contact w/ his plane when it flew into cloud.

The point is, one minute the guy was flying along VMC over a layer,
next minute WHUMP! pilot window and right rear window blown out,
pilot's headset thrown into baggage, plane flipped inverted and
dropped into IMC. Vacuum gyros tumbled, pitot-static instruments
unreliable.

Pilot saved his butt using T/C, tach, and stall warning.

So I'm not exiling my T/C or tach to Siberia on the right side of
my panel to make way for an electric horizon which might or might
not save my soup partial panel, accident record seems mixed on
this point (see for example King Air and Bandierante accident
described earlier in thread)

IMO both the T/C and the tach have proven value, both in daily
flying, partial panel, and in plausible emergencies. I want 'em
where I can see 'em, right in the primary scan.

Cheers,
Sydney

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

On 14-Jul-2003, Roy Smith wrote:

Not really. When I'm doing partial panel work, I find I miss the DG
much more than I miss the AI.


A yoke-mounted GPS in either HSI or moving map mode is a good substitute for
a failed DG. Strictly for "situational awareness" of course! You have to
be careful in that the update of the GPS display is not instantaneous like
the DG's response to heading changes, so it's easy to find yourself "chasing
the needle". That's where the backup AI comes in.

Why do you think leaving it off most of the time will extend its life?

wrote in message
...
... We leave [our electric AI] 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

I thought that gyro bearings were very susceptible to damage if subjected to
mechanical shock while not turning. If that is true, then turning it off in
flight may actually reduce the service life.

wrote:

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

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759