Grob 103 question

[Olin]

We have a G103 with an esa-systems multi function probe. The probe
serves as a static, pitot and total energy ports. The socket that it
plugs into is mounted in the vertical stabilizer and Three tubes run
forward to service flight instruments. The socket contains three o-
rings to keep the three ports separated when the probe is inserted.
These o-rings deteriorate over time of course and allow leakage
between the ports and erroneous instrument readings.

Two of the o-rings are easily replaceable from the front opening. The
third o-ring is small (~1/8" ID) and not so easily replaced as it is
deep in the socket. Wings & Wheels has a nice diagram of the socket
(type UN).

It almost looks to me like you have to dig into the vertical stab and
remove the socket and disassemble it to remove this o-ring, unless
there is a special tool or method to get it out.

Any ideas? Perhaps some of you have traveled this road before.

Thanks.

[Darryl Ramm]

On May 23, 1:00 pm, Olin > wrote:
> We have a G103 with an esa-systems multi function probe. The probe
> serves as a static, pitot and total energy ports. The socket that it
> plugs into is mounted in the vertical stabilizer and Three tubes run
> forward to service flight instruments. The socket contains three o-
> rings to keep the three ports separated when the probe is inserted.
> These o-rings deteriorate over time of course and allow leakage
> between the ports and erroneous instrument readings.
>
> Two of the o-rings are easily replaceable from the front opening. The
> third o-ring is small (~1/8" ID) and not so easily replaced as it is
> deep in the socket. Wings & Wheels has a nice diagram of the socket
> (type UN).
>
> It almost looks to me like you have to dig into the vertical stab and
> remove the socket and disassemble it to remove this o-ring, unless
> there is a special tool or method to get it out.
>
> Any ideas? Perhaps some of you have traveled this road before.
>
> Thanks.

You have it correct, you cut out the tripple probe mount to do this.
Good huh? Obviously try to confirm this is really the problem before
doing all this work (i.e. a leakdown test between the rear most and
middle ports.

I always put a tape over the probe port when not in use to keep dust
out.
Club ships etc. tied out are often best left with the probles left in
them to avoid wear and tear on the O-rings (others may disagree).
The annual was just done on my glider - including cleaning the mount
and lubricating the o-rings with a very small amount of silicone (make
sure this is being done to your glider, more frequently if the probe
is inserted/removed a lot).

Darryl

[Darryl Ramm]

On May 23, 1:27 pm, Darryl Ramm > wrote:
> On May 23, 1:00 pm, Olin > wrote:
>
>
>
> > We have a G103 with an esa-systems multi function probe. The probe
> > serves as a static, pitot and total energy ports. The socket that it
> > plugs into is mounted in the vertical stabilizer and Three tubes run
> > forward to service flight instruments. The socket contains three o-
> > rings to keep the three ports separated when the probe is inserted.
> > These o-rings deteriorate over time of course and allow leakage
> > between the ports and erroneous instrument readings.
>
> > Two of the o-rings are easily replaceable from the front opening. The
> > third o-ring is small (~1/8" ID) and not so easily replaced as it is
> > deep in the socket. Wings & Wheels has a nice diagram of the socket
> > (type UN).
>
> > It almost looks to me like you have to dig into the vertical stab and
> > remove the socket and disassemble it to remove this o-ring, unless
> > there is a special tool or method to get it out.
>
> > Any ideas? Perhaps some of you have traveled this road before.
>
> > Thanks.
>
> You have it correct, you cut out the tripple probe mount to do this.
> Good huh? Obviously try to confirm this is really the problem before
> doing all this work (i.e. a leakdown test between the rear most and
> middle ports.
>
> I always put a tape over the probe port when not in use to keep dust
> out.
> Club ships etc. tied out are often best left with the probles left in
> them to avoid wear and tear on the O-rings (others may disagree).
> The annual was just done on my glider - including cleaning the mount
> and lubricating the o-rings with a very small amount of silicone (make
> sure this is being done to your glider, more frequently if the probe
> is inserted/removed a lot).
>
> Darryl

And I forgot - Tim at Wings and Wheels normally has the ESA o-ring
kits which may be less hassle than trying to source elsewhere.

Darryl

[dsbrantjr]

On May 23, 4:00 pm, Olin > wrote:
> We have a G103 with an esa-systems multi function probe. The probe
> serves as a static, pitot and total energy ports. The socket that it
> plugs into is mounted in the vertical stabilizer and Three tubes run
> forward to service flight instruments. The socket contains three o-
> rings to keep the three ports separated when the probe is inserted.
> These o-rings deteriorate over time of course and allow leakage
> between the ports and erroneous instrument readings.
>
> Two of the o-rings are easily replaceable from the front opening. The
> third o-ring is small (~1/8" ID) and not so easily replaced as it is
> deep in the socket. Wings & Wheels has a nice diagram of the socket


> (type UN).
>
> It almost looks to me like you have to dig into the vertical stab and
> remove the socket and disassemble it to remove this o-ring, unless
> there is a special tool or method to get it out.
>
> Any ideas? Perhaps some of you have traveled this road before.
>
> Thanks.

Olin: There is an easily-obtainable instrument used for ear surgery
called an "ear polypus" which might be helpful in reaching the o-ring
to remove it and also to put a new one in. Here's a link to one
possible source: http://www.urbachletter.com/Archive/CTOM_0503_CrocodilePolypus.htm.
If the polypus cannot grab the o-ring you might be able to use it to
use a small wire hook to remove the ring. I think I paid $5 for mine
at an amateur radio hamfest. Good luck with your repair.

[Marc Ramsey[_2_]]

Darryl Ramm wrote:
> I always put a tape over the probe port when not in use to keep dust
> out.

In my opinion, this requires a disclaimer. Nothing would ever happen to
Darryl's instruments, of course, but for the rest of us, if one has
expensive mechanical varios, one would be ill-advised to place tape or
any other airtight seals on the probe port. I don't think we need
another long thread on whether or why this is a problem, but based on
first-hand (expensive) experience, don't do it. I keep a collection of
vinyl caps (available from McMaster-Carr or any large hardware store)
that fit the probe port, each with a tiny hole in the center that I made
with a heated needle...

Marc

[Darryl Ramm]

On May 23, 8:07 pm, Marc Ramsey > wrote:
> Darryl Ramm wrote:
> > I always put a tape over the probe port when not in use to keep dust
> > out.
>
> In my opinion, this requires a disclaimer. Nothing would ever happen to
> Darryl's instruments, of course, but for the rest of us, if one has
> expensive mechanical varios, one would be ill-advised to place tape or
> any other airtight seals on the probe port. I don't think we need
> another long thread on whether or why this is a problem, but based on
> first-hand (expensive) experience, don't do it. I keep a collection of
> vinyl caps (available from McMaster-Carr or any large hardware store)
> that fit the probe port, each with a tiny hole in the center that I made
> with a heated needle...
>
> Marc

Marc

Lets make it a concise short thread then. You got me - I'm not sure
how this would hurt a vane style (winter) vario or even a Sage vario
since all ports of the triple probe mechanism will be at the same
pressure and may all be increasing or decreasing in pressure (but at
the same pressure) due to temperature changes or altitude (towing
glider in the trailer). So what exactly causes the failure?

If you have separate TE/pitot etc. tail probes, or instruments cross
configured to say use the triple probe TE line but fuselage static
sources etc., then taping over a port I could see might cause damage -
but 1. that's not what was being discussed and 2. I'd also consider
cross configured pneumatic systems misconfigured. Single port devices
like the Altimeter should not be on the triple probe static port. I'd
be surprised if absolute pressure transducer electronic compensated
varios would have such little headroom they could be damage by this.

Still I'll give you that those plastic cups better than tape just
becasue they don't leave gummy residue and probably less prone to
falling off than a piece of tape.

Darryl

[Marc Ramsey[_2_]]

Darryl Ramm wrote:
> Lets make it a concise short thread then. You got me - I'm not sure
> how this would hurt a vane style (winter) vario or even a Sage vario
> since all ports of the triple probe mechanism will be at the same
> pressure and may all be increasing or decreasing in pressure (but at
> the same pressure) due to temperature changes or altitude (towing
> glider in the trailer). So what exactly causes the failure?

The relative static and pitot pressures are irrelevant, as only the TE
port is connected to a pneumatic vario, with the capacity on the other
side. Best theory I've heard (from the current owner of Sage ;^) is
that the capacity contains relatively warm air when one puts the glider
away in the early evening, which then cools at night lowering the
pressure (and tightening up the tape seal). Removing the tape in the
morning can cause a sudden influx of high pressure air, which results in
a high enough "sink" rate to bend/break delicate parts inside the vario...

Marc

[Darryl Ramm]

On May 23, 10:29*pm, Marc Ramsey > wrote:
> Darryl Ramm wrote:
> > Lets make it a concise short thread then. You got me - I'm not sure
> > how this would hurt a vane style (winter) vario or even a Sage vario
> > since all ports of the triple probe mechanism will be at the same
> > pressure and may all be increasing or decreasing in pressure (but at
> > the same pressure) due to temperature changes or altitude (towing
> > glider in the trailer). So what exactly causes the failure?
>
> The relative static and pitot pressures are irrelevant, as only the TE
> port is connected to a pneumatic vario, with the capacity on the other
> side. *Best theory I've heard (from the current owner of Sage ;^) is
> that the capacity contains relatively warm air when one puts the glider
> away in the early evening, which then cools at night lowering the
> pressure (and tightening up the tape seal). *Removing the tape in the
> morning can cause a sudden influx of high pressure air, which results in
> a high enough "sink" rate to bend/break delicate parts inside the vario...
>
> Marc

Oh doh, sounds good to me. I guess I'm lucky and/or just have the
elcheapo type mechanical varios. So good point.

Darryl

[[email protected]]

> Two of the o-rings are easily replaceable from the front opening. *The
> third o-ring is small (~1/8" ID) and not so easily replaced as it is
> deep in the socket. *Wings & Wheels has a nice diagram of the socket
> (type UN).
>
> It almost looks to me like you have to dig into the vertical stab and
> remove the socket and disassemble it to remove this o-ring, unless
> there is a special tool or method to get it out.

Check with Monty Sullivan at M&H in the US. Years ago he described
replacing o-rings in a triple probe on one of M&H's projecgts using a
crochet hook or something similar. He said it was a challenge but he
was able to do it. I don't know if he replaced all three o-rings or
just the easier-to-reach first two.

Chip Bearden
ASW 24 "JB"
USA

[bumper]

"dsbrantjr" > wrote in message
...
>
> Olin: There is an easily-obtainable instrument used for ear surgery
> called an "ear polypus" which might be helpful in reaching the o-ring
> to remove it and also to put a new one in. Here's a link to one
> possible source:
> http://www.urbachletter.com/Archive/CTOM_0503_CrocodilePolypus.htm.
> If the polypus cannot grab the o-ring you might be able to use it to
> use a small wire hook to remove the ring. I think I paid $5 for mine
> at an amateur radio hamfest. Good luck with your repair.


I also suffer tool addiction. Have all three sizes of the Crocodile Polypus
(got the wife convinced tools are "off budget" and don't count against one's
toy account) - - got them at tool stores over the years.

Haven't needed to replace the O-rings in probe socket - yet. If the small
O-ring failed, I'd sure be tempted to try almost anything rather than
cutting holes in the tail. How about removing the old O-ring using a
modified dental pick (bend a small 90 degree in a long skinny pick)? I'd
also try viewing the procedure with a bore-sope, I've got one that's .165"
OD, but they are available much smaller. It would be possible to insert
bore-scope alongside probe being used to remove old O-ring.

To insert the new O-ring, I'd make an insertion tool using thin-wall SS
outer housing. Compressed O-ring would be pushed out of tube with plunger.

bumper

[Darryl Ramm]

On May 24, 8:10 am, "bumper" > wrote:
> "dsbrantjr" > wrote in message
>
> ...
>
>
>
> > Olin: There is an easily-obtainable instrument used for ear surgery
> > called an "ear polypus" which might be helpful in reaching the o-ring
> > to remove it and also to put a new one in. Here's a link to one
> > possible source:
> >http://www.urbachletter.com/Archive/CTOM_0503_CrocodilePolypus.htm.
> > If the polypus cannot grab the o-ring you might be able to use it to
> > use a small wire hook to remove the ring. I think I paid $5 for mine
> > at an amateur radio hamfest. Good luck with your repair.
>
> I also suffer tool addiction. Have all three sizes of the Crocodile Polypus
> (got the wife convinced tools are "off budget" and don't count against one's
> toy account) - - got them at tool stores over the years.
>
> Haven't needed to replace the O-rings in probe socket - yet. If the small
> O-ring failed, I'd sure be tempted to try almost anything rather than
> cutting holes in the tail. How about removing the old O-ring using a
> modified dental pick (bend a small 90 degree in a long skinny pick)? I'd
> also try viewing the procedure with a bore-sope, I've got one that's .165"
> OD, but they are available much smaller. It would be possible to insert
> bore-scope alongside probe being used to remove old O-ring.
>
> To insert the new O-ring, I'd make an insertion tool using thin-wall SS
> outer housing. Compressed O-ring would be pushed out of tube with plunger.
>
> bumper

Getting the o-rings out as bumper suggests should not be a problem.
The first two come out easily with a dental pick. I am not sure the
Crocodile Polypus would help - but I also want a set for my toolbox.
Push new o-rings in place with a plunger made from a piece of brass
rod. The second o-ring will slide over the first with a bit of
fiddling. I luckily avoided having to replace the third one. Again in
my case the damage was frequent removal/insertion of the triple probe
in a club ship. You could see the flat spots where th o-rings had been
abraded and there were very fine black rubber specks in the mount that
were likely from the o-rings. removed the first two o-rings cleaned
out very carefully with non-lint wipes and then installed the first
and then second o-ring and just lubricated the third.

If abrasion like this is the culprit the third o-ring may be in a much
better state becasue very little length of probe rubs past it when the
probe is installed.

Bumpers suggested tool sound like it could work - I'll take one from
the first batch :-)

BTW I just noticed on the esa-systems web site "adapter AV" - a plug
with attachment hole for a "remove before flight" flag and Marc it
looks like it does have a vent hole. (I wonder if W&W stocks those).

Darryl