GRUMMAN AMERICAN TIGER PLT NOTICED SMOKE COMING FROM CIRCUIT BREAKER BOARD DURING INITIAL CLBOUT AFTER TKOF CAUSING HIM TO NOTIFY UNICOM THAT HE WAS RETURNING TO LAND. SMOKE DISSIPATED DURING APCH AND LNDG.

Narrative

AFTER A ROUTINE TKOF ON RWY; I WAS CLBING THROUGH 1000 FT MSL ON A XWIND LEG DEP; WHEN A 1-2 SECOND ERUPTION OF SMOKE EMERGED FROM NEAR THE CIRCUIT BREAKER PANEL; ON THE LOWER R PORTION OF THE INST PANEL. THE 'ALT' CIRCUIT BREAKER TRIPPED; WITH SUBSEQUENT CESSATION OF SMOKE FLOW. I PROMPTLY NOTIFIED THE UNICOM OPERATOR OF MY SIT; CONFIGURED FOR APCH; AND MADE A ROUTINE LNDG ON RWY. ON THE GND; A LCL A&P INSPECTED ON A COURTESY BASIS; FOR FREE; UNDERNEATH THE PANEL; WITH NO SIGNS OF BURNT WIRES; SCORCHING OR FIRE. THE 'ALT' CIRCUIT BREAKER FAILED TO RESET AFTER PWR DOWN. POSSIBLE RELATED FACTORS: MASTER SWITCH LEFT ON INADVERTENTLY THE 'ON' POS FOR 30-45 MINS PRIOR TO FLT; DURING MEAL BTWN LEGS. ACFT STARTED EASILY; AND AMMETER DID NOT INDICATE EXCESSIVELY HIGH CHARGE; AND PRETKOF RUNUP WAS UNEVENTFUL. LATER ON; THE OWNER'S MECH HAD NOT FULLY DIAGNOSED THE PROB; LOCATED THE GND FAULT (IF ANY) OR REPLACED THE AFFECTED CIRCUIT BREAKER. I CALLED THE FAA ON THE INCIDENT DAY; AS THE AFTER HRS NTSB RPTING POINT; ON AN ANONYMOUS BASIS; DETERMINED THAT THIS EVENT DID NOT CONSTITUTE AN 'INFLT FIRE' AND NOT SUBJECT TO 'IMMEDIATE RPTING' UNDER NTSB PART 830.