Aircraft: Fusioncopter JK-2 Nano
Serial no: FCG014
Engine: Hirth F23
TIS: 25 hours
History: On pre-flight run-up checks, one ignition was found to be inoperative.
Analysis: One ignition kill wire was permanently grounded.
Traced to the 3PDT ignition master switch- one pole permanently made irrespective of switch position.
Switch was disassembled and one pole rocker was found welded in the made position.
The other ignition kill pole rocker also showed signs of arcing.
The switch is rated at 2A/260VAC- but the ignition circuit generates voltages well in excess of that.
The failure mode is most likely arcing/welding at the moment just prior to the switch closure to kill the ignition.
The switch was replaced with the same type as an interim fix until a higher rated compatible switch is found.
Recommend that Fusioncopter upgrade the switch rating.
Thank you so much for sharing this! Really appreciate this information.
Further to this-
I have now adopted the practice of shutting down the F23 by using the ignition test buttons as part of a shutdown mag drop check.
This is based on the assumption (?) that the test pushbuttons are more robust and have a higher voltage rating than the toggle switch, so better resistant to arcing.
Also detects any issue with the ignition system at end of flight rather than the next preflight when you are all geared up to fly.
-Test1 mag drop
-Test2 mag drop
-Test1 and Test 2 engine shutdown
-Ignition switch OFF