A BE9L crew experienced smoke in the cockpit while cruising at FL210, they diverted to huf.

Attributes
ACN	545556
Time
Date	200204
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : huf.airport
State Reference	IN
Altitude	msl single value : 21000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	general aviation : corporate
Make Model Name	King Air C90 E90
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	VFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : commercial pilot : cfi pilot : atp pilot : instrument
Experience	flight time last 90 days : 40 flight time total : 3470 flight time type : 300
ASRS Report	545556
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : provided flight assist flight crew : landed in emergency condition flight crew : declared emergency flight crew : diverted to another airport
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Smoke appeared from an unknown source in the cockpit. I notified ZAU of the situation asking for a descent and vectors to the nearest airport. The smoke appeared to be tan, so I performed all checklist items for electrical smoke. After landing at terre haute, firemen boarded the aircraft noting that the smoke was beginning to clear. They were unable to determine the source and could not see any additional smoke. I notified my director of maintenance of the situation. We discussed what had happened, what actions I had taken, and that the firemen found no evidence nor any new smoke. We decided to slowly restore power to the aircraft, checking for evidence of smoke after each switch was moved. After starting both engines, I accomplished an electrical system check, noting no abnormalities and no new smoke. It was decided to continue the flight and I checked every 5 mins for smoke but none appeared. The flight was accomplished to the planned destination without further incident.

Original NASA ASRS Text

Title: A BE9L CREW EXPERIENCED SMOKE IN THE COCKPIT WHILE CRUISING AT FL210, THEY DIVERTED TO HUF.

Narrative: SMOKE APPEARED FROM AN UNKNOWN SOURCE IN THE COCKPIT. I NOTIFIED ZAU OF THE SIT ASKING FOR A DSCNT AND VECTORS TO THE NEAREST ARPT. THE SMOKE APPEARED TO BE TAN, SO I PERFORMED ALL CHKLIST ITEMS FOR ELECTRICAL SMOKE. AFTER LNDG AT TERRE HAUTE, FIREMEN BOARDED THE ACFT NOTING THAT THE SMOKE WAS BEGINNING TO CLR. THEY WERE UNABLE TO DETERMINE THE SOURCE AND COULD NOT SEE ANY ADDITIONAL SMOKE. I NOTIFIED MY DIRECTOR OF MAINT OF THE SIT. WE DISCUSSED WHAT HAD HAPPENED, WHAT ACTIONS I HAD TAKEN, AND THAT THE FIREMEN FOUND NO EVIDENCE NOR ANY NEW SMOKE. WE DECIDED TO SLOWLY RESTORE PWR TO THE ACFT, CHKING FOR EVIDENCE OF SMOKE AFTER EACH SWITCH WAS MOVED. AFTER STARTING BOTH ENGS, I ACCOMPLISHED AN ELECTRICAL SYS CHK, NOTING NO ABNORMALITIES AND NO NEW SMOKE. IT WAS DECIDED TO CONTINUE THE FLT AND I CHKED EVERY 5 MINS FOR SMOKE BUT NONE APPEARED. THE FLT WAS ACCOMPLISHED TO THE PLANNED DEST WITHOUT FURTHER 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.