As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TRAINING FLIGHT, INSTRUCTOR AND STUDENT NOTICED SMOKE COMING FROM LANDING LIGHT SWITCH. INSTRUCTOR IMMEDIATELY TURNED MASTER SWITCH OFF AND PROCEEDED BACK TO BASE. INSPECTION IN MAINTENANCE REVEALED LANDING LIGHT BREAKER SWITCH INOPERATIVE. REPLACED WITH NEW P/N CM3589-10. SYSTEM OPS CK OK. NO EXTERNAL OR WIRING DAMAGE.