JPI EGT probe failure typical signs

My #3 EGT usually works just fine but every once in a while it will
jump up to an unreasonable number or even just report "OPEN PROBE" on
the screen. It may do this for several minutes and then just come back
and work just fine. JPI says to first swap it with another (#1 EGT) and
see if its the probe. However, if I'm going to go out to the airport,
put on my grubbies, decowl the plane, etc and there is a say 60% chance
the problem is the probe, I'd rather just buy a new probe and try that
right away.

Does having the probe go on and off line during flight a typically
failure method for JPI EGT probes?

-Robert

"Robert M. Gary" wrote:

Does having the probe go on and off line during flight a typically
failure method for JPI EGT probes?

I don't have a problem with my JPI EGT probes, but I have been experiencing
similar, intermittent problems with my JPI RPM probe/connection/??? over
the last year.

This shows up as a sudden drop of the RPM on my EDM800 down to zero, then
back up, or down to some unreasonable level, such as 1200, then back up
perhaps ten minutes later.

The mechanic has checked the connections twice and replaced the wire once
but it still is happening. Either it is vibrating loose or perhaps the TKS
anti-ice fluid that I have been running all winter is corroding the
connection?


--
Peter

Robert M. Gary wrote:
My #3 EGT usually works just fine but every once in a while it will
jump up to an unreasonable number or even just report "OPEN PROBE" on
the screen. It may do this for several minutes and then just come back
and work just fine. JPI says to first swap it with another (#1 EGT) and
see if its the probe. However, if I'm going to go out to the airport,
put on my grubbies, decowl the plane, etc and there is a say 60% chance
the problem is the probe, I'd rather just buy a new probe and try that
right away.

Does having the probe go on and off line during flight a typically
failure method for JPI EGT probes?

-Robert

EGT probes, of any type, provide very small (millivolt) signals to the
gauge itself. I recently had a devil of a time with an Insight system
exhibiting symptoms similar to yours. DVM showed good output and good
insulation, but indeed there were several, almost microscopic,
insulation cracks near the probe. In flight, under vibration, the wire
was shorting to airframe ground.

Rip

It MIGHT be the probe but it is more typical of a bad crimp joint in a
connector somewhere in the circuit to the probe.

On 1 Mar 2006 16:16:47 -0800, "Robert M. Gary"
wrote:

My #3 EGT usually works just fine but every once in a while it will
jump up to an unreasonable number or even just report "OPEN PROBE" on
the screen. It may do this for several minutes and then just come back
and work just fine. JPI says to first swap it with another (#1 EGT) and
see if its the probe. However, if I'm going to go out to the airport,
put on my grubbies, decowl the plane, etc and there is a say 60% chance
the problem is the probe, I'd rather just buy a new probe and try that
right away.

Does having the probe go on and off line during flight a typically
failure method for JPI EGT probes?

-Robert

Check the plug on the back of the EDM unit also - it's possible to
jiggle things loose back there. I had my OAT probe go off line after
the annual a while back; the mechanic had knocked the wire loose while
working on avionics.

No experience with JPI. But on my EI, each probe could be unpluged
from the scaner. I had problem with #6 once. I unpluged #6 & 4, and
pluged #6 probe to #4 on scaner, and #4 to #6 on scaner. Fly it & now
problem is #4 in the scaner & #6 probe. Ordered & changed probe in #6,
& everything is fine.