As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB JUST AFTER TAKE-OFF CREW SELECTED GEAR UP, GEAR DID NOT RETRACT, FOLLOWED BY LG AIR/GRD FAIL CAS MESSAGE. CHECKLIST FOLLOWED, EMERGENCY DECLARED, AND UNSCHEDULED UNEVENTFUL LANDING PERFORMED. MAINTENANCE EVALUATION FOUND NOSE GEAR WOW PROXIMITY SWITCH CHECKED BAD. VISUAL INSPECTION OF NOSE GEAR PROX SWITCH CONNECTOR FOUND A CORRODED AND BURNT PIN. REMOVED AND REPLACED NOSE GEAR PROX SWITCH P/N OFF 80-057-01 S/N OFF 16815. REMOVED AND REPLACED NOSE GEAR PROX SWITCH WIRING HARNESS P/N OFF 145-21495-405 S/N OFF OP33146982.