The FlightCom 403
in my RV-12 quit working. I removed the unit from the panel and heard something loose inside. I took off the top cover plate and discovered a nut and insulator bushing the holds a power transistor heatsink vibrated loose and fell on the circuit board. The remaining screw without its insulator allowed the power transistor to short-circuit against the metal case. The real problem is when the 403
quits working it prevents audio from the comm radio to reach the headsets.
A new (used) 403
is now on order and I will remove the top cover plate and put some adhesive on the exposed thread to prevent recurrence.