Narrative:

The flight was in and out of numerous rain showers and temperature at 14000 ft was zero to -2 degrees C. I was trained to turn on anti-ice from below 10 degrees C. The flowing items were on: all radios, navs, radar, strike finder, argus, ADF, transponder, RNAV, GPS, intercom. In addition, the following items were on: stall warning heat, fuel vent heat, pitot heat and when in rain I would put the propeller heat on. At approximately 1.45 mins into my flight, I was at 14000 ft with discretion to 7000 ft and approximately 65 mi to my destination, I smelled something. I immediately looked down and saw smoke coming into the cabin from under my yoke below my switches. I immediately told ATC and was cleared to 4000 ft. I began an emergency descent, dumped the cabin pressure and turned all the switches and avionics off except the radio and GPS. Smoke continued for approximately 30 seconds and I removed the fire extinguisher and opened my side window as I leveled at 4000 ft. I requested the closest airport and they vectored me to kerrville and cleared me for the approach. The smoke had stopped at this time and broke out into VFR approximately 5 mi to the airport and landed immediately. Upon landing, I shut everything down and went to the FBO and called to cancel and let ZHU know I was on the ground without incident.

Google
 

Original NASA ASRS Text

Title: BE58 PLT HAD SMOKE IN THE COCKPIT IN ZHU CLASS E AIRSPACE.

Narrative: THE FLT WAS IN AND OUT OF NUMEROUS RAIN SHOWERS AND TEMP AT 14000 FT WAS ZERO TO -2 DEGS C. I WAS TRAINED TO TURN ON ANTI-ICE FROM BELOW 10 DEGS C. THE FLOWING ITEMS WERE ON: ALL RADIOS, NAVS, RADAR, STRIKE FINDER, ARGUS, ADF, XPONDER, RNAV, GPS, INTERCOM. IN ADDITION, THE FOLLOWING ITEMS WERE ON: STALL WARNING HEAT, FUEL VENT HEAT, PITOT HEAT AND WHEN IN RAIN I WOULD PUT THE PROP HEAT ON. AT APPROX 1.45 MINS INTO MY FLT, I WAS AT 14000 FT WITH DISCRETION TO 7000 FT AND APPROX 65 MI TO MY DEST, I SMELLED SOMETHING. I IMMEDIATELY LOOKED DOWN AND SAW SMOKE COMING INTO THE CABIN FROM UNDER MY YOKE BELOW MY SWITCHES. I IMMEDIATELY TOLD ATC AND WAS CLRED TO 4000 FT. I BEGAN AN EMER DSCNT, DUMPED THE CABIN PRESSURE AND TURNED ALL THE SWITCHES AND AVIONICS OFF EXCEPT THE RADIO AND GPS. SMOKE CONTINUED FOR APPROX 30 SECONDS AND I REMOVED THE FIRE EXTINGUISHER AND OPENED MY SIDE WINDOW AS I LEVELED AT 4000 FT. I REQUESTED THE CLOSEST ARPT AND THEY VECTORED ME TO KERRVILLE AND CLRED ME FOR THE APCH. THE SMOKE HAD STOPPED AT THIS TIME AND BROKE OUT INTO VFR APPROX 5 MI TO THE ARPT AND LANDED IMMEDIATELY. UPON LNDG, I SHUT EVERYTHING DOWN AND WENT TO THE FBO AND CALLED TO CANCEL AND LET ZHU KNOW I WAS ON THE GND WITHOUT INCIDENT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.