Resolved CubCrafters Lycoming cc363i erratic RPM and now running rough on R lightspeed ignition

[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.

 

[Cubonaut875]

I would assume these coil packs are used for certified airplanes as well. Are the specs the same for experimental coil packs equivalent to those used for certified planes? Maybe that is a question for Klaus.

 

[Neal]

I’m happy to report Klaus is going to warranty replace this one. He again reiterates how critical it is that spark plug wires are seated properly and securely as I’m sure mine are after November.

 

[Neal]

Well, something is going on somewhere and I don't know what. Today was supposed to be another long day of flying but I was tired so I chose to just go enjoy the evening after dinner. Runup was perfect and off I went. On takeoff again like last weekend I noticed a sound or feel that wasn't quite right, I checked the RPM and it was fine. I go to lean assist and I already see 3/4 EGT's are running up (last week was 1/2) and yep, leaning is going to run this through 1500 so I turn around and land. I do a runup when clear and again R ignition is rough. So now it's the right ignition opposite pair from last time. Just like last November, dual coil pack failure on the right side.

I have emails out to Lightspeed, now to email CubCrafters. I wonder if I have a bad set of spark plugs? Ignition module? No clue as to what's causing this. It's been perfect for 25 hours since the last time this was changed. Is it a bad batch of coil packs? Plugs were changed in November out of an abundance of caution even though I just replaced them at the condition inspection in July/August.

 

[Neal]

Klaus emailed me back this morning after a few follow-ups I provided such as how it's odd that both R ign coil packs failed each time, near simultaneously. He agreed and suggested I send in the ignition module. It would take a day to inspect it. Well, that's all well and good except that getting the ignition module out is another story and I tried and it's not happening. I replaced the failed coil pack and did a ground run and it checks good. If this happens a third time then I may replace spark plug cables or something along that line. Still waiting to hear Pete's suggestions from CubCrafters support.

 

[Neal]

Klaus called me yesterday afternoon to discuss spark plugs. I had read on the CubCrafters forums the possibility of chinese knock off spark plugs on the market and apparently there was an issue with Denso some time ago. I told him the plugs I've been using were from Amazon and that raises some concern. Apparently you need to be very careful where you buy spark plugs. I told him I ordered 24 directly from Denso as I wanted to ensure this was not a cause of my problem. Apparently you can't get them from Denso, I was slightly misunderstanding who I was buying them from but where I ordered he said is one of the correct suppliers, which I'll link below. They're using a separate domain name but ultimately it's coming from sparkplugs.com which is a reputable distributor.

I changed my plugs out at my condition inspection in July/August, and as they are only around $10/plug from Amazon I changed them again in November during my dual coil pack failure. As I ordered 24 from the link below it was a little over $8/plug. They should be arriving today and then I'll pull all the plugs, resistance check what comes out of the engine and also borescope the engine while I'm decowled as I just bought a borescope not long ago.

Klaus mentioned the plugs should have a resistance of 4-6 kohm so I'll test the plugs coming out and the ones going in. He also asked me about the gap and I told him they measure .031 out of the box and I didn't want to risk breaking the electrode to get them to the recommended .032 as I felt .031 was fine and that they open up over time with usage. He agreed, .031 is fine, if you have too much gap that can cause coil pack problems. He mentioned Bosch makes a good gap tool if needed, I'll just gently use my blade tool to verify 0.031/0.032.

We then discussed spark plug cables and he said pull them straight off, don't rock them side to side. If you get the prongs opened up that can cause arcing and coil pack failures. While I'm confident mine are/were secure, I will inspect them and try to use pliers to see if I can close up the prongs a little to ensure a secure fit when re-attached.

I heard from Pete as well from CubCrafters, he mentioned a few things regarding spark plug wires as well but ultimately he's awaiting feedback from anything I learn. If this happens again I will have no choice but to pull the ignition module and send it to Klaus. I'm hoping it doesn't come to that. As most of the builders know those go in nearly first thing after the fuselage is assembled and it's not the joyous task but it's doable, I just don't want to risk that right now.

Here's the link to one of the reputable sources for the Denso IK27 plugs which I have coming today. Again, I'll be resistance checking between the electrode and opposite end to ensure 4-6 kohm to quality check the plugs prior to install.

Denso 5312 IK27 Iridium Power Spark Plug

Denso 5312 IK27 Iridium Spark Plug - Same Day Shipping. Free Returns. PayPal Accepted. Secure Online Ordering. Est. 1969.

www.densoproducts.com