CubCrafters Lycoming IO-360 (cc363i) erratic RPM and now running rough on R lightspeed ignition

[Neal]

Well, it's been a joyous week of a lot of labor that if I couldn't have done this myself probably would have cost me a fortune. One heck of a learning experience and good stuff to learn so all good in the end.

So I had TWO BAD COIL PACKS. Prior to today 3 of them were changed and I still had erratic RPM on the L ignition so I decided to change out the 4th one, so all of them got either a swap or new. All 3 of my new coil packs are in use, I figured why deal with moving what is probably a good existing one over when I have new so I used the new ones. After replacing L ignition cylinders 3/4 (upper right coil) voila, my problem is gone! RPM is now stable.

Flight tested good with solid RPM at 2680 at WOT.

In talking with Lightspeed they have had some quality issues with the manufacturer of these coils, sadly, so getting these original ones out makes me feel better, I still have one in play and will leave it unless another problem presents itself.

 

[Neal]

Here is a video on this saga for those interested:

 

[Neal]

Stardate: MAY 24 2025
Plan: Get out of the local area, head west for new grass strips, put 5+ hours on and enjoy a full day in the cub. Something I haven't done since bringing it home.
Weather: Too windy, reschedule for tomorrow
Plan B (2 hours prior sunset): Winds calmed down, go fly local

Over recent past I've been getting ADSB FAIL anomalies on takeoff, not sure why, it seems to correct itself. So bank this issue, the cause may be what's coming next.

Preflight, all good, I inspect all connectors I can see, always use a flashlight to look in the side gills. Runup good, no issues noted. Takeoff was fine but something didn't seem quite right power wise but RPM and all checked good. Leveled off and powered back to around 20 squared, noticed 1 was higher EGT than others by about 130 degrees. 2 was around 30 less. Used lean assist and noticed 1 was running up in EGT fast, hmm, odd. Back to full rich, let it stabilize for a few minutes. Lean assist again and EGT is in the high 1400's and approaching 1500. Time to air abort and return home, something isn't quite right.

Landed. Did a post flight ground run and R is rough. Tried R in emergency, rough.

So it seems the coil pack for R1/2 is bad. This one was replaced 6 months and 25 tach hours ago. I'll replace it tomorrow and I'll reach out to Klaus and see if he will warranty replace it but I'm guessing it's going to be a no.

Very very sad. You better be carrying a spare coil pack. Today again was a day this would have found me 1.5 hours away from home just like the last time, in almost the same location I flew 6 months ago when this happened on the way home.

Anyone looking to buy a stupid expensive cub. Go find the absolute best J-3 you can find instead.

P.S. back to the ADSB issue, it seems these coil pack failures show a precursor of electrical anomalies. My bet is the coil pack was the cause of the ADSB problem.

 

[ve6yeq]

Is the “ADSB FAIL” from the G3X or the GNC 355?

For me, the traffic on the G3X Touch has always been stable but the traffic on the GNC 355 is often not working, I assume that it is a cabling issue as the serial connection to the G3X appears more stable than the ethernet connection to the GNC 355. (I have swapped the GNC 355 so I a pretty sure that the issue is in the cabling not the GNC)

 

[Neal]

I don't remember the message and I haven't been running my GoPro's but last night I did just in case it came on again and I had to seek support for it. It's happened about 3 times now, I think it's yellow large letters on the ADSB screen of the GNC 355 that I'm typically on and in the transponder section at the top left of the G3X. I'm hoping it's stray trons from the coil pack but I'll continue to monitor.

You may need your transponder firmware updated. It's the one thing we can't do ourselves, supposedly per Pete. Avionics is supposed to do the updates on this. I'm coming due for my every two year transponder cert so I need to check versions and consider having them update it.

 

[Cubonaut875]

That is crazy that it would happen again to the same coil pack! Very odd. Something to keep a double check on for sure.

 

[Neal]

That is crazy that it would happen again to the same coil pack! Very odd. Something to keep a double check on for sure.

I’m hoping this is the lone original coil pack. Three were replaced.

 

[Cubonaut875]

Keep us posted!

 

[Neal]

It was a bad coil pack. Ohm test at 3 Kohm, normal is 16. It was a new coil pack from lightspeed date code 0824 from last November. As two I pulled that were original and I marked “likely good” ohm checked good and installed instead of another new one just because I think it’s still good. Engine run tests perfect. IA was on board for verification and sign off with treat bribes. Obviously mutt muffs are not working. Trying her with the new Rex specs hearing protection for dogs. I think the one I got is too small so tried these again. I digress.

Approximately 1.5 hours to decowl and replace coil pack. Now to reassemble

 

[Tsquared]

I’ve been planning on ordering some spare coil packs but haven’t pulled the trigger yet. I’m very interested to hear what the Mfg has to say on why such a new coil pack with so few hours on it failed. It has me thinking I should delay any purchase to avoid getting a few from that same batch.

Nice to see the pup supporting your maintenance efforts.

 

[ve6yeq]

I don't remember the message and I haven't been running my GoPro's but last night I did just in case it came on again and I had to seek support for it. It's happened about 3 times now, I think it's yellow large letters on the ADSB screen of the GNC 355 that I'm typically on and in the transponder section at the top left of the G3X. I'm hoping it's stray trons from the coil pack but I'll continue to monitor.

I am seeing the same issue on the GNC 355. It seems to appear more often when there is no other traffic anywhere in range (Canada does not have ADS-B ground stations like the US so I get weather, notams, etc. via SirusXM). I wonder if there is a shielding issue on the Ethernet connection that makes it sensitive to electrical noise?

You may need your transponder firmware updated. It's the one thing we can't do ourselves, supposedly per Pete. Avionics is supposed to do the updates on this. I'm coming due for my every two year transponder cert so I need to check versions and consider having them update it.

I have the GTX 45R and the firmware update is possible as the windows software to update it via USB (USB connector is under the panel just behind the USB power) is available on the Garmin site. I need to install a Windows VM on my MacBook Pro and see if the USB will connect.

 

[Neal]

I've only seen the issue a few times, not sure the cause, maybe asking on the CC Facebook Official Support page you can get some answers or other people to chime in what they've seen.

I've seen that USB dongle but Pete said it was for Avionics to do but yeah, I was tempted to try. Let me know how it goes. I think it may be due to that the transponder has to be "certified" every two years and if you screw something up you may not even know it. I don't know, I'm new to all of this but I do like to try to keep things up to date as much as possible.

Maybe emailing g3xpert would be something to try as well?

 

[Neal]

Flew 1.6 yesterday evening, post maintenance flight, EGT's were about as even across the board as I've seen. All checks good. At least it's nice to finally recognize this situation and know how to fix it.

 

[Cubonaut875]

Is there anything with our planes that could cause a failure of a coil pack? Kinda strange, seems like those coil packs are not just used on Carbon Cubs.

 

[Neal]

I'm no expert and really can't answer it but my opinion is yes, there are probably a lot of factors that could cause it but it could also be a quality issue as Klaus told me over the phone he's had to send some back to the manufacturer. However, one thing I hate that are used for the coil pack connections are spade connectors. They come loose, in fact the yellow (comm) cable spade had opened the jaws up slightly so I recrimped it tighter when reconnecting after replacing the coil pack. I think soldering the connection would be better and then have a wire connector that can be unplugged along the cable run would be a better connection, and not a spade connection but something more reliable for electronics, power supply, etc. I think spades & crimps are the number one cause of problems in CubCrafters' planes. I wish the coil packs themselves had wires coming out and not spade terminals.