2 CHT sensors out after Surefly installation

[Coryb]

2 EGT sensors out after Surefly installation

I've had my RV-9A for a little over a year. I had my first condition inspection done by an IA at a destination airport. I wasn't involved. I just trusted the IA and came back a couple days later when he was finished. This time I did an owner assist CI at my home airport with a friend who is an IA. When looking at the logbooks we noticed that the mags haven't been overhauled in almost 1,000 hrs. I decided to replace the left mag on my O-320 with a Surefly electronic ignition and then send out the R slick mag to get overhauled.

The installation went well and when the CI was complete everything looked good and the engine run-up and checks.

On my first flight I decided to go and do some touch and gos. There was no problem on the first time around. However as I took off after the first touch and go I noticed the #2 and #4 EGT readouts on the Dynon Skyview were bouncing all over the place. By the time I made it around to land (decided to do a full stop and take a look) I had a red X on the #2 and #4 readout.

I didn't see anything obvious when I looked at the EGT sensor connections but I decided to replace one of the connections just to see. It did not help. For some background I did need to replace both EGT sensors on the other side (#1 and #3).

What are the chances that both EGT sensors would go out at the same time and both on the same side? Could it have anything to do with the Surefly? It seems unlikely to me. Does anyone have any suggestions? I talked to Surefly they don't see how they could be related (I agree). Did we do something in the CI that may have caused it? If so what?

SO sorry on my original post I wrote CHT sensor. I was thinking EGT the whole time and just wrote the wrong thing

 

[gasman]

I've had my RV-9A for a little over a year. I had my first condition inspection done by an IA at a destination airport. I wasn't involved. I just trusted the IA and came back a couple days later when he was finished. This time I did an owner assist CI at my home airport with a friend who is an IA. When looking at the logbooks we noticed that the mags haven't been overhauled in almost 1,000 hrs. I decided to replace the left mag on my O-320 with a Surefly electronic ignition and then send out the R slick mag to get overhauled.

The installation went well and when the CI was complete everything looked good and the engine run-up and checks.

On my first flight I decided to go and do some touch and gos. There was no problem on the first time around. However as I took off after the first touch and go I noticed the #2 and #4 CHT readouts on the Dynon Skyview were bouncing all over the place. By the time I made it around to land (decided to do a full stop and take a look) I had a red X on the #2 and #4 readout.

I didn't see anything obvious when I looked at the CHT sensor connections but I decided to replace one of the connections just to see. It did not help. For some background I did need to replace both CHT sensors on the other side (#1 and #3).

What are the chances that both CHT sensors would go out at the same time and both on the same side? Could it have anything to do with the Surefly? It seems unlikely to me. Does anyone have any suggestions? I talked to Surefly they don't see how they could be related (I agree). Did we do something in the CI that may have caused it? If so what?

Did you send out the impulse mag for repair? I would expect you did. If so, it goes on the left side, in front of the pilot, normally. And the Surefly on the right.

Give the wiring a really close look. Interesting that you worked in that area, and now, two failures on the same side. Or was it prefect timing??

 

[Coryb]

The surefly is on the left and is an impulse. And yes I did send out the R slick mag which has been rebuilt.

 

[BobTurner]

The surefly is on the left and is an impulse.

Minor quibbles:
The surefly is not an ‘impulse’, but it does retard the timing for starts.
You know you only need an A&P, not necessarily an AI, to do your non-builder condition inspections?
Now the real question, re: CHT probes. These normally last a long time. But you’ve had two fail before, now two more? I would check for something weird, like maybe they’re the wrong size for your engine? More than one mechanic has replaced a failed part with the same as removed, without checking to see if the failed part was correct in the first place. Or maybe something else is wrong. Get the engine manual and check.
BTW, with an ignition system that is now electrically dependent, do you have a back up electric power source?

 

[sailvi767]

He is still running a mag on one side. The FAA accepts that in certified installations without back up power.

 

[lr172]

If two CHT sensors failed after a CI, I would first suspect that the wires were moved or damaged by the mechanic. They don't fail that often and two failing at the exact same time, immediately after working on the engine, really points to some human intervention. While the ign should not cause this, I have experienced that auto plug wires (not shielded stuff) placed in close proximity to the probe wires can cause erratic readings.

The fact that you replaced ignitions right before the problem appeared, I suspect that some wires may have been moved around and now are too close to CHT wires.

Larry

 

[Coryb]

SO SO Sorry, I had a brain fart! I wrote down CHT but all along I meant EGT sensor. I know that makes a big difference. Has anyone lost 2 Dynon EGT sensors at the same time? Or is it most likely a connection?

 

[BobTurner]

Well, egt probes do wear out. And often die with the symptoms you described (erratic, then dead). I’d check their connections, and if they’re okay, just chalk it up to bad luck.

 

[kiwipete]

Corby

The original Dynon egt probes had a problem and only lasted 2-300 hours. Not sure if the ones they supply these days are better. I replaced mine with Electronics international ones and have had no problems since. Yes they are more expensive to buy but then you’re paying for quality.

Regards Peter