As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) V-NAV SELECTOR SWITCH MOVED INADVERTENTLY BETWEEN POSITIONS DUE TO WORN SWITCH. THIS DISABLED THE ALTITUDE ALERTER AND AIRCRAFT DESCENDED BELOW ASSIGNED ALTITUDE. SWITCH HAS BEEN SAFETIED IN ALERTER POSITION UNTIL PARTS ARE AVAILABLE. PLACARD INSTALLED IN COCKPIT TO PROVIDE WARNING OF V-NAV INOPERATIVE STATUS.