As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE PROP SYNCROPHASER BECAME INOP DUE TO AN ON/ON SWITCH BEING USED INSTEAD OF AN ON/OFF SWITCH. BEECH IS USING A THREE-POLE SWITCH AND THE ONE BARE UNPROTECTED TERMINAL HAS POWER SWITCHED TO IT WHEN YOU THINK IT IS SELECTED TO THE OFF POSITION. THIS HAS OCCURRED ON FOUR OTHER AIRCRAFT. (X)