First the AI, then the DG, then...?

A couple of months ago our AI, which had been "coming and going", finally
went. We replaced it with a rebuilt unit from "The Gyro House", which had
the dual effect of getting our autopilot working properly again.

Last month, our DG failed completely and suddenly, after a normal landing in
Pella, IA. Before that landing it worked, after that landing it didn't.
And the autopilot -- connected to the DG, too -- stopped working again.

So, I've just received a rebuilt unit from the Gyro House. As a precaution
(I'm assuming some sort of contamination caused the second failure), I've
ordered new vacuum hoses -- enough for my A&P to replace all the hoses, from
the vacuum pump to the firewall, and from the firewall to the two vacuum
instruments. I'm also having him replace all the filters.

Short of replacing the vacuum pump itself (which is still working fine), is
there anything else I should be watching?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Intake filter, regulator, vac gauge accuracy....

Rip

Jay Honeck wrote:
A couple of months ago our AI, which had been "coming and going", finally
went. We replaced it with a rebuilt unit from "The Gyro House", which had
the dual effect of getting our autopilot working properly again.

Last month, our DG failed completely and suddenly, after a normal landing in
Pella, IA. Before that landing it worked, after that landing it didn't.
And the autopilot -- connected to the DG, too -- stopped working again.

So, I've just received a rebuilt unit from the Gyro House. As a precaution
(I'm assuming some sort of contamination caused the second failure), I've
ordered new vacuum hoses -- enough for my A&P to replace all the hoses, from
the vacuum pump to the firewall, and from the firewall to the two vacuum
instruments. I'm also having him replace all the filters.

Short of replacing the vacuum pump itself (which is still working fine), is
there anything else I should be watching?

In a previous article, "Jay Honeck" said:
Short of replacing the vacuum pump itself (which is still working fine), is
there anything else I should be watching?

Practice partial panel much lately?


--
Paul Tomblin http://xcski.com/blogs/pt/
You know the saying, every time you develop an idiot proof system they
develop a better type of idiot... and now you know who "they" are.
-- Matthew Malthouse

Do you have a wet pump or dry pump? You may give the place you traded
your old one into a call and ask what they found while repairing it.
Regular wear or contaminants. Then again, you just may have been
unlucky. What did the Gyro House hit you up for the A/P DG?


On Fri, 28 Nov 2003 03:32:13 GMT, "Jay Honeck"
wrote:

A couple of months ago our AI, which had been "coming and going", finally
went. We replaced it with a rebuilt unit from "The Gyro House", which had
the dual effect of getting our autopilot working properly again.

Last month, our DG failed completely and suddenly, after a normal landing in
Pella, IA. Before that landing it worked, after that landing it didn't.
And the autopilot -- connected to the DG, too -- stopped working again.

So, I've just received a rebuilt unit from the Gyro House. As a precaution
(I'm assuming some sort of contamination caused the second failure), I've
ordered new vacuum hoses -- enough for my A&P to replace all the hoses, from
the vacuum pump to the firewall, and from the firewall to the two vacuum
instruments. I'm also having him replace all the filters.

Short of replacing the vacuum pump itself (which is still working fine), is
there anything else I should be watching?

In article 1lzxb.331132$Tr4.1006704@attbi_s03, Jay Honeck
wrote:

A couple of months ago our AI, which had been "coming and going", finally
went. We replaced it with a rebuilt unit from "The Gyro House", which had
the dual effect of getting our autopilot working properly again.


Hmmmm... Your landing or Mary's? :-)

What did the Gyro House hit you up for the A/P DG?

$515, plus tax and shipping.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

A couple of months ago our AI, which had been "coming and going",
finally
went. We replaced it with a rebuilt unit from "The Gyro House", which
had
the dual effect of getting our autopilot working properly again.


Hmmmm... Your landing or Mary's? :-)

Mine. Funny thing was, it was one of my better landings! :-)

A friend of mine says that the gyros inside ride on some sort of a "ruby
bearing" -- and that they eventually wear out. Sometimes the rotor (or
whatever) even falls right off the bearing. When that happens, everything
just stops -- like mine did.

Or something like that. Either way, it's just more money...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
: Short of replacing the vacuum pump itself (which is still working fine), is
: there anything else I should be watching?

As others have said, check the accuracy of the vac gauge, because extra-high
vacuum will make the gyros "over-rev" and wear their bearings quite quickly.

You might want to look at the inline filter STC that inserts a filter in the
suction line between the regulator and the vacuum pump. The theory is that
if the pump fails, the carbon vanes blow up into dust which gets sucked back
into the lines and instruments by residual vacuum. This in-line filter
supposedly traps all of that carbon dust, preventing the lines, regulator,
and instruments from becoming contaminated. When the pump is replaced, the
filter needs to be replaced as well.

As I recall, the same fellow that holds the M-20 air/oil seperator STC holds
this in-line vacuum filter STC.

--
Aaron Coolidge (N9376J)

"Jay Honeck" writes:

As a precaution
(I'm assuming some sort of contamination caused the second failure), I've
ordered new vacuum hoses -- enough for my A&P to replace all the hoses, from
the vacuum pump to the firewall, and from the firewall to the two vacuum
instruments. I'm also having him replace all the filters.

A somewhat dumb question. Each vacuum-driven instrument has its
own input filter, correct? The hoses and pumps are then all downsteam
of the instrument.

Does garbage really migrate upstream into the expensive toys? (And
if so, you'd thunk someone would add a inline filter between the
toy and the common vacuum line..)

Education welcomed.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

David Lesher
shared these priceless pearls of wisdom:

-
-A somewhat dumb question. Each vacuum-driven instrument has its
-own input filter, correct? The hoses and pumps are then all downsteam
-of the instrument.

Sometimes. More often there is one very large filter with two outlets (or a
single outlet with an installer's T fitting) for both vacuum gyros.


-
-Does garbage really migrate upstream into the expensive toys? (And
-if so, you'd thunk someone would add a inline filter between the
-toy and the common vacuum line..)

Not really. The carbon dust that comes off of a normally operating pump gets
ported overboard and the big chunks that come off of a pump in failure mode get
thrashed about until they are small enough to be blown overboard OR remain in
the pump as mute testimony to the advantages of a wet pump.


-
-Education welcomed.

And is generally expensive, but not as expensive as ignorance (Twain).


Jim
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com