As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKE OFF APPROXIMATELY 10 MILES FROM AIRPORT COCKPIT AND CABIN BEGAN FILLING WITH SMOKE. CABIN LIGHT CIRCUIT BREAKER OPENED. PILOT RETURNED TO AIRPORT AND MADE AN UNEVENTFUL LANDING. UPON TROUBLESHOOTINGFOUND FLUORESCENT LIGHT BALLAST ASSEMBLY PN 6900042 TO BE RUPTURED AND EMITTING SMOKE.