Narrative:

It was an overcast day. Temperature hovering around freezing. There was no visible moisture in the air, but there was no doubt a narrow margin between dewpoint and temperature. My intent was to stay in the traffic pattern practicing touch-and-goes in high wing/tricycle. After the customary preflight, I taxied out for departure. The standard before takeoff checklist was performed. The static run-up and carburetor heat check at 1700 RPM indicated no reason to be concerned. On the downwind leg I applied full carburetor heat before throttle back. There was no indication of engine roughness or any loss of RPM. After touching down, I proceeded to retract flaps, close carburetor heat and apply full throttle. I climbed to 500 ft MSL when within a time span of about 5 seconds I detected a loss of RPM and suddenly the engine quit. Primer, ignition, throttle, mixture all checked out. I was able to maintain best glide and set down on a nearby highway. The landing was otherwise uneventful. After being towed back to the airport, inspection and test flight all proved negative. Conclusion was carburetor icing had occurred. I had always been taught that carburetor ice at full power is not of concern. After reading a number of articles recently on this topic, I have concluded that carburetor ice can occur very quickly given the right meteorological conditions even at full power. In the future I will closely monitor the dewpoint/temperature spread. I will also be ready to respond faster with carburetor heat at the first sign of RPM slippage, even if at full power. And, when in doubt I will trade off touch-and-goes for full stop lndgs, rechking engine run-up each time or better yet, stay on the ground and wait for a better day to fly.

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Original NASA ASRS Text

Title: SMA PLT PRACTICING TOUCH-AND-GO LNDGS HAS ENG QUIT ON TKOF. OFF FIELD LNDG.

Narrative: IT WAS AN OVCST DAY. TEMP HOVERING AROUND FREEZING. THERE WAS NO VISIBLE MOISTURE IN THE AIR, BUT THERE WAS NO DOUBT A NARROW MARGIN BTWN DEWPOINT AND TEMP. MY INTENT WAS TO STAY IN THE TFC PATTERN PRACTICING TOUCH-AND-GOES IN HIGH WING/TRICYCLE. AFTER THE CUSTOMARY PREFLT, I TAXIED OUT FOR DEP. THE STANDARD BEFORE TKOF CHKLIST WAS PERFORMED. THE STATIC RUN-UP AND CARB HEAT CHK AT 1700 RPM INDICATED NO REASON TO BE CONCERNED. ON THE DOWNWIND LEG I APPLIED FULL CARB HEAT BEFORE THROTTLE BACK. THERE WAS NO INDICATION OF ENG ROUGHNESS OR ANY LOSS OF RPM. AFTER TOUCHING DOWN, I PROCEEDED TO RETRACT FLAPS, CLOSE CARB HEAT AND APPLY FULL THROTTLE. I CLBED TO 500 FT MSL WHEN WITHIN A TIME SPAN OF ABOUT 5 SECONDS I DETECTED A LOSS OF RPM AND SUDDENLY THE ENG QUIT. PRIMER, IGNITION, THROTTLE, MIXTURE ALL CHKED OUT. I WAS ABLE TO MAINTAIN BEST GLIDE AND SET DOWN ON A NEARBY HWY. THE LNDG WAS OTHERWISE UNEVENTFUL. AFTER BEING TOWED BACK TO THE ARPT, INSPECTION AND TEST FLT ALL PROVED NEGATIVE. CONCLUSION WAS CARB ICING HAD OCCURRED. I HAD ALWAYS BEEN TAUGHT THAT CARB ICE AT FULL PWR IS NOT OF CONCERN. AFTER READING A NUMBER OF ARTICLES RECENTLY ON THIS TOPIC, I HAVE CONCLUDED THAT CARB ICE CAN OCCUR VERY QUICKLY GIVEN THE RIGHT METEOROLOGICAL CONDITIONS EVEN AT FULL PWR. IN THE FUTURE I WILL CLOSELY MONITOR THE DEWPOINT/TEMP SPREAD. I WILL ALSO BE READY TO RESPOND FASTER WITH CARB HEAT AT THE FIRST SIGN OF RPM SLIPPAGE, EVEN IF AT FULL PWR. AND, WHEN IN DOUBT I WILL TRADE OFF TOUCH-AND-GOES FOR FULL STOP LNDGS, RECHKING ENG RUN-UP EACH TIME OR BETTER YET, STAY ON THE GND AND WAIT FOR A BETTER DAY TO FLY.

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.