Small aircraft has engine quit on base leg. Lands unlighted runway.

Attributes
ACN	250479
Time
Date	199309
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : osh
State Reference	WI
Altitude	agl bound lower : 300 agl bound upper : 300
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : osh
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	landing other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi
Experience	flight time last 90 days : 8 flight time total : 1720 flight time type : 8
ASRS Report	250479
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

I was returning to the airport after about a 1/2 hour local flight. As I entered the pattern on a base leg, I checked the carburetor heat, applied full rich mixture, turned on the fuel pump. The engine was operating normally. When I reduced power further on base, the engine started running rough and then quit. I reapplied carburetor heat and checked my magnetos and gas. Due to my altitude I had to divert to a closer runway which was unlighted. The landing was made without any problems. After towing the aircraft back to the hangar the fuel sumps were checked for contamination. They were ok. Each fuel tank had about 1/2 tank of fuel remaining. An engine restart was then attempted and the engine started and ran normally during a runup. I believe that the cause of this engine failure was carburetor ice. I think that the best way to prevent this in the future is to use carburetor heat at all times on base and final.

Original NASA ASRS Text

Title: SMA HAS ENG QUIT ON BASE LEG. LANDS UNLIGHTED RWY.

Narrative: I WAS RETURNING TO THE ARPT AFTER ABOUT A 1/2 HR LCL FLT. AS I ENTERED THE PATTERN ON A BASE LEG, I CHKED THE CARB HEAT, APPLIED FULL RICH MIXTURE, TURNED ON THE FUEL PUMP. THE ENG WAS OPERATING NORMALLY. WHEN I REDUCED PWR FURTHER ON BASE, THE ENG STARTED RUNNING ROUGH AND THEN QUIT. I REAPPLIED CARB HEAT AND CHKED MY MAGNETOS AND GAS. DUE TO MY ALT I HAD TO DIVERT TO A CLOSER RWY WHICH WAS UNLIGHTED. THE LNDG WAS MADE WITHOUT ANY PROBS. AFTER TOWING THE ACFT BACK TO THE HANGAR THE FUEL SUMPS WERE CHKED FOR CONTAMINATION. THEY WERE OK. EACH FUEL TANK HAD ABOUT 1/2 TANK OF FUEL REMAINING. AN ENG RESTART WAS THEN ATTEMPTED AND THE ENG STARTED AND RAN NORMALLY DURING A RUNUP. I BELIEVE THAT THE CAUSE OF THIS ENG FAILURE WAS CARB ICE. I THINK THAT THE BEST WAY TO PREVENT THIS IN THE FUTURE IS TO USE CARB HEAT AT ALL TIMES ON BASE AND FINAL.

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.