Cleaning a 3-way TE probe

I have a vertical-stabilizer mounted TE probe of the type that has 3
ports: ram, static, and venturi. I have been having problems with my
varios and LNAV and had previously checked out the plumbing but had
only looked at the "outside" end of the TE probe itself, which I
remove after each flight. Today I finally thought to look at the butt
end of the TE probe and discovered "junk" (uncertain whether its dried
grease or animal reside/excretion or what) on the ram and static port
outlets! I have cleaned them off as mcuh as possible from the outside
using an unbent paper clip, and air now moves through all 3 ports.
However it's probable that the same "junk" is on the inside of the
female attachment, into which the TE probe is inserted so I feel I
should clean that also. But I can't see much inside it and have no idea
what is in there and if there is something to watch out for in doing
that cleaning. Is it as simple as using a Qtip and denatured alcohol
as I was planning on doing? If anyone has had experience cleaning out
that receptacle I'd appreciate hearing about it.

"Jack Glendening" wrote in message
news:5o5gb.4451 But I can't see much inside it and have no idea
what is in there and if there is something to watch out for in doing
that cleaning. Is it as simple as using a Qtip and denatured alcohol
as I was planning on doing? If anyone has had experience cleaning out
that receptacle I'd appreciate hearing about it.


Yup, it's that simple. Cut a Q-tip and find a short length of stiff tubing
that will be a tight fit on the cut-off Q-tip shaft. This will allow you to
reach down all the way into the probe hole. There are several (at least 3)
O-rings down there, so go gently.

When done cleaning, I like to put a small amount of either silicone spray or
synthetic grease (very small amount!) on the probe shaft base so as to
lubricate the O-rings when it's inserted. If the probe is now easy to insert
(it should be), it'll also be easy to remove . . . maybe even in flight due
to vibration, so it's a good idea to tape around the fin fitting and probe
when installing it.

If you regularly remove your probe, consider a plug for the hole on the
vertical fin to keep dirt out. I also use a tubular cover for the base end
of the probe to keep it clean too.
--
bumper - ZZ
"Dare to be different . . . circle in sink."
to reply, the last half is right to left


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"John Morgan" wrote...
If you regularly remove your probe, consider a plug for the hole on the
vertical fin to keep dirt out. I also use a tubular cover for the base end
of the probe to keep it clean too.

Make sure that plug isn't airtight (put in pinhole in it, or something), or
you'll probably be in the market for some new varios in the near future...

Marc

Dr. Jack,
Good stuff from Marc & John, also There ia a possibility that bugs have made a
home in the female hole (was that crude?) I have found an insect known as a
"Leaf-roller" in my probe holes (like that better?) Plug it when not in use,
with a small bleeder hole.

Now, if a leaf-roller has been at work in your hole, you may have shoved its
home way down inside your probe hole. Very bad news, you need to take your
probe hole to a hole checking (gynecologist) They masquerade as
glider-repairmen, but they are all just a bunch of hole checkers at heart. They
will flush out your hole by carefully applying pressure from the other end of
all the tubes that are attached to your hole. They know that ALL instruments
must be disconnected BEFORE giving your hole and associated tubing any
pressure. They also know that over-pressure can result in an aneurysm or even
worse, a blow-out deep inside your precious little darling.
JJ Sinclair

Thanks to Bumper (John), Marc, and JJ for passing on your knowledge. I
am going out to work on this today and test the pluming and see what I
find. Hopefully I'm get everything working early as it looks like an
excellent soaring day. I went flying yesterday but with, in retrospect,
the pitot and static TE ports blocked had no working vario or computer
so was not able to take much advantage of the conditions then - I was
wondering why my LNAV kept telling me I had a 50 kt tailwind! I might
have already damaged the mechanical vario per Marc's comment as I went
up to 8000 ft with the static port apparently blocked.

Regarding "leaf rollers", a few weeks ago I had to work on my
motorglider's (bear with me here JJ, stop gnashing your teeth) motor
retraction and the motor was extended for a long period. I happened to
notice an insect which seemed to be periodically flying in and out of
the motor, near the metal cooling fins on the cylinder. Finally when I
again saw it disappear in there I went and looked and found way back a
bug's eyes looking out at me! That thing did not want to budge, as I
tried poking in with a screwdriver (which could not fit all the way in
to the hole) and the bug stubbonly remained. Finally I found a long
very thin screwdriver and managed to kill it, but the fact that this bug
was seeming to want to make a hole in my engine certainly made an
impression! So perhaps this was one of those "leaf rollers". I had
been putting some white tape over the TE probe hole between uses, but
one time I noticed that the tape had not stayed attached so it is
certainly possilbe that something got in there, particularly since there
have been long periods when the plane has not been flown. Anyway, will
see what I find today.

I spent 4 hours today cleaning out junk from my TE tube "hole", didn't
get to fly. I had to use both mechanical and liquid means to get out
a lot of what must be insect byproduct - reminds me of yellow/orange
ear was. Final status is that the static port of the hole is no longer
blocked but the pitot port remains blocked. Using a bicycle pump I put
some pressure on that port and it help air nicely at 10 psi (mindful of
JJ's warning I didn't put any more pressure on it). Time now to find
a "hole" expert - I will first see if the mechanic at the local
gliderport has any "holy" experience. JJ, one thing that bothers me
is that it seems possible that _no_ amount of reasonable pressure
might not open the port - in which case I think I am in for a lot of
trouble. In the meantime I plan to get a T fitting and put the LNAV
on the airspeed pitot pressure as being better than nothing and
getting me back up in the air. And allowing me to test the LNAV since
I have never had it working correctly since I bought the plane and I
hope this might explain why. I had thought the problem lay in the
LNAV itself but perhaps it lay in the TE probe.

One thing I noticed while I was working was that there were a whole
lot of ants (about 30 at one time) crawling in a line up the front
of the vertical stabilizer to the top of the elevator (just above the TE
hole) where they milled around acting like they were looking for
something. They did this for about an hour, then disappeared for an
hour, then re-appeared for another hour. I couldn't see ants elsewhere
on the plane, which made me wonder whether they might be associated with
the insect "junk" in the TE hole - I had swabbed out the hole with
alcohol by that time and since ants rely on leaving chemical messenges
those would have been "erased" inside the hole itself. Likely there is
another explanation (possibly the ants are just like glider plots and
like to climb and stay high) but it did make me wonder if anyone else
had ever experienced problems caused by ants entering their glider.

"Jack Glendening" wrote in message
k.net...

In the meantime I plan to get a T fitting and put the LNAV
on the airspeed pitot pressure as being better than nothing and
getting me back up in the air.

Not quite sure what you meant by the above comment. The pitot for the L-Nav
should always be connected to the same pitot port as the airspeed indicator.
If you use the L-Nav for speed-to-fly info, it should come from the same
source as supplied to the airspeed indicator that you fly by. Of course
this is not necessary. You can have L-Nav info based on one pitot reading
and airspeed indicator based on another. But, it would be nice to have the
info correlated. Hopefully both pitot reading would be the same, but, that
is not always true.

Duane

Welcome to the insect world, Dr. Jack. I once had the little buggers fill my
hole in one afternoon, as I attended to some routine items on the ship. I
religiously keep the hole covered, now.

You can apply reverse pressure to your pitot, static and TE lines from the
instrument panel. be sure to remove ALL connections to your instruments first.
Then I give each line, short bursts, of compressed air, as I watch the hole for
debris exiting.

Your L-Nav should be on the ships pitot & static system, also check the ASI
calibration page for correct numbers (see manual) the constant tail-wind sounds
like a pitot problem, L-Nav not generating a good TAS, so it must drive in a
big tail wind to make things equal out with the GS its getting fron thr GPS.

Its only October, you got all winter to work on this. Don't you just love a
challenge? :)
JJ Sinclair

"Jack Glendening" wrote in message
.net...
Duane Eisenbeiss wrote:
Not quite sure what you meant by the above comment. The pitot for the
L-Nav
should always be connected to the same pitot port as the airspeed
indicator.

Right now the LNAV pitot and static info is taken from the TE probe
while the airspeed/altimeter values are taken from different probes. It
was my understanding that using a separate pilot+static for the LNAV was
better since the pitot and static measurments are then closer to the
free-stream values than those taken by the "normal" probes, which are
closer the fuselage.

Use whichever ports (pitot & static) suit you, however, it is best to have
both instruments connected to the same ports.

Duane

On Tue, 07 Oct 2003 03:52:39 GMT, "Duane Eisenbeiss"
wrote:

"Jack Glendening" wrote in message
k.net...
Duane Eisenbeiss wrote:
Not quite sure what you meant by the above comment. The pitot for the
L-Nav
should always be connected to the same pitot port as the airspeed
indicator.

Right now the LNAV pitot and static info is taken from the TE probe
while the airspeed/altimeter values are taken from different probes. It
was my understanding that using a separate pilot+static for the LNAV was
better since the pitot and static measurments are then closer to the
free-stream values than those taken by the "normal" probes, which are
closer the fuselage.

Use whichever ports (pitot & static) suit you, however, it is best to have
both instruments connected to the same ports.

Duane


Actually the pitot/static from a dual or triple probe is probably the
best you are going to get on a glider. The Prandtl (combined
pitot/static) well forward of the LE of the fin and stab will have
small errors which you most likely won't have to correct in your
computer. This makes the computer easier to install and tune.

The ASI must be connected to the pitot/static sources specified in the
flight manual as all placarded limits are based in these. The ASI may
have quite large errors as a result as it helps the advertising
writers(stalls slow, runs real fast)


Mike Borgelt

Borgelt Instruments