Narrative:

While taxiing out to active runway; I noticed a voltage fluctuation. I contacted ground control and stated that I was having a charging system problem and needed to return to my hangar. Ground gave me new taxi instructions and I complied. While circling back smoke begin to enter the cockpit from the glove box area (to the right of copilot's yoke). I called ground again and advised that I believed I might have an electrical fire. Requested direct to the fire station on the field and this was immediately granted. Ground controller said she would phone fire station. I cut all electrical power at this point and taxied to the fire station where I killed the engine with the mixture; then shut off mags. I evacuated 3 passengers; then grabbed the extinguisher. Fireman were around the plane by this time. I retrieved a toolbox from the baggage compartment and uncowled the engine with the firemen holding an extinguisher at the ready. There was no smoke or evidence of fire in the engine compartment and no longer any smoke in the cockpit. I climbed back into the cockpit and investigated the glovebox area. At this time the cigar lighter power resistor was found to be very hot. Aircraft was towed to maintenance. Upon investigation; it was found that one of the connections to the power resistor was quite loose. This apparently increased the resistance and i2R heat production at that point. The resistor is bolted to the aluminum bottom of the glove box. The heat melted a pen in the glovebox and badly charred a wooden pencil. This was apparently the source of the smoke. The power resistor was replaced and the circuit now checks out ok.

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Original NASA ASRS Text

Title: P210N pilot reported seeing smoke in the cockpit during taxi; so he headed for the fire station. Smoke was traced to an overheating power resistor.

Narrative: While taxiing out to active runway; I noticed a voltage fluctuation. I contacted ground control and stated that I was having a charging system problem and needed to return to my hangar. Ground gave me new taxi instructions and I complied. While circling back smoke begin to enter the cockpit from the glove box area (to the right of copilot's yoke). I called ground again and advised that I believed I might have an electrical fire. Requested direct to the fire station on the field and this was immediately granted. Ground controller said she would phone fire station. I cut all electrical power at this point and taxied to the fire station where I killed the engine with the mixture; then shut off mags. I evacuated 3 passengers; then grabbed the extinguisher. Fireman were around the plane by this time. I retrieved a toolbox from the baggage compartment and uncowled the engine with the firemen holding an extinguisher at the ready. There was no smoke or evidence of fire in the engine compartment and no longer any smoke in the cockpit. I climbed back into the cockpit and investigated the glovebox area. At this time the cigar lighter power resistor was found to be very hot. Aircraft was towed to maintenance. Upon investigation; it was found that one of the connections to the power resistor was quite loose. This apparently increased the resistance and i2R heat production at that point. The resistor is bolted to the aluminum bottom of the glove box. The heat melted a pen in the glovebox and badly charred a wooden pencil. This was apparently the source of the smoke. The power resistor was replaced and the circuit now checks out OK.

Data retrieved from NASA's ASRS site 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.