On Sunday afternoon on May 28th, 2017 I was doing some pattern work (Runway 16) at my home base, Carrol County Regional Airport (KDMW). It has been a while since I last flew (1 month), and wanted to “knock the dust off” with a few touch and go’s. The startup and first two takeoffs were very normal. On the third takeoff, I noticed on my crosswind to downwind turn, my tachometer indication on my EFIS was registering 0 RPM as I pulled back the throttle once I reached pattern altitude. I also noticed the engine began to run a little rough and the EGT’s were spiking. It was clear my EMAG electronic ignition had just failed.
Simultaneously I noticed my EFIS give me high voltage warnings on my primary and secondary busses. I don’t recall the exact voltages, but they were higher than 15V. At this time I decided to turn off the alternator field voltage (disengage the alternator). This did not seem to fix the voltage issue – the alternator was still outputting excessive voltage. Since I was within gliding distance of the airport and no other traffic was in the pattern, I decided the safe option was to turn off the entire electrical system via the master switch. The engine would still be producing power with the Slick magneto still functional, and I was well within gliding distance of the runway. It seemed like the safe bet since I was clearly having an overvoltage event, and I felt this course of action was better than watching the alternator voltage continue to climb and potentially cause an electrical fire.
Upon turning off the relay, the smell of burning electrical components quickly filled the cabin. Some strange electrical phenomenon occurred as well – the strip of LED’s I have over my panel lit up (controller by a panel dimmer, which was in the off position). I taxied to the hangar and shut the airplane down. I turned on the master switch and noticed the following items not working:
1) Trim indicators
2) Both PFD and MFD EFIS’s
3) COM2 Radio
4) Instrument Lights
5) Panel Lights
I turned the power off and crawled under the panel to find the following fuses blown:
• Grand Rapids EFIS 1, Feed 1 (GRT Sport EFIS PFD) [5A]
• Grand Rapids EFIS 1, Feed 2 (GRT Sport EFIS PFD) [5A]
• Grand Rapids EFIS 2, Feed 2 (GRT Sport EFIS MFD) [5A]
• Grand Rapids ARINC Module [1A]
• COM2 (Icom A210) [10A]
• ADS-B Receiver (Garmin GDL39) [5A]
• ADS-B Transceiver (NavWorx ADS-600EXP) [3A]
• Panel/Hood Light [4A]
• Trim Servo Controller [1A]
• Trim Indicators [2A]
• Electronic Ignition (EMAG) [5A]
• GPS #2 (Garmin 18x-LVC) [1A]
I removed the engine cowling next. I found some black dust over the firewall and on the bottom of the lower cowl. I was able to locate the source of the black dust – the alternator. The alternator was extremely hot to the touch – seemed hotter than the cylinder heads. I removed the alternator to find the shaft was not turning freely. There was also some noticeable binding in portions of the shaft rotation. Upon removal of the alternator, a similar black dust fell out of the unit as was found on the lower cowl and firewall.
The inside of the lower cowling was covered with bits of black material. I had never seen this before.
The top of the FAB also had black dust-like material on it.
Clearly the alternator was the first thing I was suspect of, so off it came.
I yanked out everything in the panel to give it the smell test. EFIS's and COM2 were definitely cooked.
Good news - the GTN650 seemed to be working! It was locking onto satellites and COM transmit and receive worked. So the the PS Engineering PDA360EX audio panel.
Some of the hood LED lights were also fried - oh, and the hood lights potentiometer was in the off position when I took this pic. Looks like the lighting controller is also cooked.
The good old reliable 327 is still functioning!
The GRT ARINC module is cooked.
I yanked off the EMAG - as it was the original culprit it definitely needed to be sent back.
UGH! Not what I wanted to find. Half of the cotter pin had sheered off and was somewhere in the engine. NOT GOOD. When I found this, it was definitely time to head home and pour a tall one. A cotter pin being loose in the engine is not something I even want to think about.
Last Modified: August 12, 2019