Insight Graphical Engine Monitor

[140KIAS]

Does anybody out there have any experience of the Insight Graphical Engine Monitor (GEM).

Our C182 had one installed when we purchased it 2 years ago. Suspect it was installed about 7-8 years ago. It ran fine until earlier this year when one of the cylinder displays started jumping erratically. We had our engineers look at it during the annual and a fault was identified on the #3 cyl CHT probe and the probe was replaced.

However on the first flight following the annual we discovered that now all 6 cylinder displays were exhibiting the same erratic jumping.

We returned it to the maintenance company and they took a further look at it during the 50 hour check. This time the #3 EGT probe was diagnosed to be faulty and they also identified a problem with the way the unit was earthed. We strongly believed that the earthing issue was a red herring. Might well have been earthed wrongly but it didn't stop it from working properly before.

Anyway the EGT probe was replaced and they declared that the problem was fixed. However same problem flying it back following the 50 hour.

By this time we had expended quite a bit of money and were reluctant to throw anymore money at it without some guarantees of a fix. Engineers kindly offered to take a look at it FOC so up we went again.

This time I suggested that perhaps a call to Insight might actually help shed some light on the issue. Due to time differences Insight got back to them after I had left for home before it got dark. The advice we are now being given is that :


After approx 10 years the GEM system starts to fail.
The EGT probe should be automatically changed after 5 to 6 years.
The CHT probe should be changed after 7 to 8 years.
The plasma display will give up with age causing a fading in and out.
Being wired wrong since day 1 didn`t help the system.


Not withstanding the fact that we had already laid out for replacing 2 probes and the engineers would have probably continued replacing everything before thinking of calling the manufacturers (fit new aircraft to yoke) I cant help but think that a 10 year lifespan is quite poor. Some aircraft have avionics in them that look like they came out of the arc.

We are at a bit of a crossroads now as to where we go with this. We do like the extra peace of mind the engine monitor gives however we don't want to continue funding on the job training/trial and error.

Does anyone have any experience of this unit and if so does the advice we are now being given seem sound. Any suggestions on what the best course of action might be next. ie forget it, get a JPI etc

[IO540]

I think you are getting the usual UK avionics shop "expertise" there :)

The Insight unit is quite popular in the USA, though not as popular as the much more marketed JPI one, and in Europe GEM never made much progress (compared to JPI) presumably due to the very strong avionics distributor channel brand loyalty.

There are no general reliability issues on the GEM. Have you called their US head office? They are said to be responsive.

The CHT probes should last "for ever" because they don't get very hot. EGT probes are something else; they will always fail eventually (due to erosion by the hot gases, until the metal is eaten all the way through) but JPI ones fail much sooner because they are thinner-wall. IME the JPI ones last a few years.

If you had multiple channels show a fault, that would be an instrument issue, possibly on the connector but much more likely internal.

Earthing is a redherring; the probes are thermocouple probes which go all the way back to the instrument and there is no earthing involved. The power -ve terminal goes to the airframe but if this was missing it would not work in the first place :) In terms of connections, these instruments are fairly simple; you have the power and then you have a bundle of thermocouple probes whose 2-core cables (made of special t/c wire) go straight back to the instrument.

One can get probe faults caused by bad connections within the probe leads, which usually have a joint somewhere; the probe comes with maybe a 2ft lead and this has to be joined to a t/c cable which then goes to the instrument. These joints can be flimsy if done badly, and a lot of avionics wiring is dry-crimped which is a recipe for bad joints - but this would not explain all 6 going.

You may just have had a random failure - the usual causes tend to be corrosion (damp over the years) or vibration.

I would deal with the US company always. There is no warranty now so dealing with anybody in the UK is pointless.

A JPI unit won't be any better. I've seen the inside of an EDM700 and the build quality is not great.

[140KIAS]

IO - many thanks for the input. Got the engineering company to phone the Head Office, thats where the info that everything needs replaced came from.

Regards the earthing. I think it was suggested that it was earthed back to the avionics master switch rather than the engine block. Might not have been right but it worked previously and changing it didnt resolve the problem.

[IO540]

Why don't you speak to them yourself? The avionics shop may have reasons to not pass on all the details - if they don't understand the installation. Best to be pro-active in this game :)

I normally contact the firm in question and return the unit to them for checking. You don't need an avionics shop to remove some piece of avionics. And reinstallation is just 4 screws and the connector in the back. And if it isn't your only (certified) primary CHT/EGT indication, you don't need it for flight anyway.