Alt Circuit Breaker Popped Twice Yesterday

[lrobichaux]

I’m working to download the actual data file and will post that up too.

Will load up CSV files later this afternoon.

 

[Cubonaut875]

Thread 'A look at FlySto.net - amazing tool for flight analytics'

Apr 6, 2025

FlySto — Flying stories you can trust

FlySto — innovative avionics log and flight data analysis software

flysto.net

• Neal
• Replies: 13
• Forum: Articles of interest (or videos)

That's it - thanks!

 

[lrobichaux]

Three files attached. The file dated 12/15 ending with "KDTO" is the first flight of the day with no abnormal electrical indications. The file dated 12/15 ending in "KRPH" is the last flight of the day during which the ALT circuit breaker popped. Abnormal indications can be seen for approx. 18 minutes with VOLT1 at which time the CB popped. CB was reset which resolved the abnormal voltage indications for the few minutes left in the flight.

Lastly, the file dated today ending in "30F" reflects a lengthy run-up this morning after inspecting the alternator connection, battery connections and connections at the firewall terminal block (all were normal). This morning, I did as good of a visual inspection as possible - no abnormalities were noted. Note that I pulled the ALT CB during this run-up today just to observe the VOT1 indication with the breaker pulled. All appeared normal.

Any ideas would be much appreciated.

 

[Neal]

The files didn't attach, please try again.

Bummer when you can't find the "smoking gun."

 

[lrobichaux]

Had to change file name extension. See attached.

 

[Neal]

What was the original file extension and I'll see if I can fix up the forum'ware for future uploads.

 

[lrobichaux]

Yes, the website does not accept CSV files. I converted to Excel and it accepted the files.

 

[Neal]

CSV is allowed now.

 

[Neal]

Had to change file name extension. See attached.

Hopefully @Cactus Charlie can take a look at the files you posted in this post when he has time.

 

[Cubonaut875]

I'm just taking a wild stab at this- Neal you remember when your ignition was about to fail that there were weird electrical things that happened? Same with me, I had weird fuel flow readings that caused me to take the whole cowling off and test fuel pressure, tested just fine and then an ignition coil failed. Replaced the coil and suddenly the fuel flow was fine. Remember - I'm a mostly retired orthodontist with zero engineering experience.

 

[Neal]

Yes, I had all kinds of issues with the coil packs failing but never an ALT breaker popping. I did have a FLD (field) breaker pop once when I tried using the USB port to power a GoPro from the GMA 245R. Wouldn't rule it out but sure seems like either a bad alternator or suspect wiring/connection. Reminder I'm no A&P or orthodontist and I'm just a mutt and relatively new aircraft owner trying to learn the ropes and keep safe

 

[Neal]

@lrobichaux has Pete provided any insight? Is a warranty replacement of the Alternator an option? I don't know if they can cause this or just completely fail. I hear they are robust. But hate to see whatever is causing your ALT breaker to pop.

 

[Cubonaut875]

Yeah - they said the coil packs were robust and almost never fail

 

[Neal]

Yeah - they said the coil packs were robust and almost never fail

LOL - good point

 

[lrobichaux]

Good morning, all. Pete suggested I take the steps outlined in Service Bulletin XK-SB004 focused on improper hardware installed at the factory to attach the alternator wire at the alternator "B" terminal. Yesterday morning, I removed the cowling and did just that. Everything was tight, correct with zero signs of interference, arcing or any sort of abnormality. I traced the charging wire back to the firewall and all was normal. I checked connections to the main battery and starter relay which are located in the aft avionics bay. All connections were tight and normal. Buttoned everything up and did an extended ground run, which was normal.

The CC393 does not use the same EIS as the CC363. I believe my engine has the Lycoming EIS which does not have external coil packs.

@Cactus Charlie is still looking at the data files and may have additional thoughts. Unless he finds something to investigate, my plan is to take it to my avionics shop to install the Hall effect sensor that that @Cactus Charlie mentioned and also have the shop see if they can find anything. If nothing turns up, I'm going to fly it locally until the problem repeats. Recall that I upgraded my right ignition IBBS to a 6AH battery, so I'm confident I will be able to safely return to an appropriate maintenance shop in the event the breaker pops again.

Appreciate the input.