Narrative:

While cruising at 4500 ft MSL. I added power to adjust my altitude. I was actually 100 ft lower than 4500 and wanted to get back up. When I pushed the throttle in, the engine faltered and lost power. Upon retracting the throttle to the original setting, the engine regained that power, after a couple more attempts were made to adjust power, I found that if I retracted power I could not gain it back. Given the high humidity and the fact that all of the engine monitoring instruments were normal, I felt I was experiencing ice build-up in the intake system. Not having carburetor heat. I decided to make an emergency landing at the nearest runway which was jackson, about 4 mi to the east. Without radio, I intermittently activated my ELT as I descended to the airport, in an attempt to attract attention. As I approached the runway I picked up the departing traffic and made sure to stay clear and was able to land between departing and landing aircraft without endangering anyone, and exited the runway into the grass immediately. The tower personnel did not even know I landed until the FBO called them asking if they were aware of me. I went up and spoke with them explaining myself as I have done here. I feel that the high humidity on that particular day caused ice buildup in the intake system. I've flown the aircraft for 140 hours since 1988, and have had no problems as such, but I don't recall every flying in such humid conditions. The plane was started about 5 mins after landing. It ran rough for about the first 30 seconds of adding throttle, went back down and added throttle a second time. The engine attained and maintained its normal static RPM, this was repeated 3 times. Because of the heat, I pulled the aircraft into a hangar on the field, decowled it, and gave it a thorough looking over, finding nothing unusual. I started and taxied the plane out and flew it home later that evening when the temperature cooled down. With the tower's permission and light signals I took off and climbed over the runway to 5000 ft MSL. When all seemed well, I wagged my wings and departed to the east for mettetal airport, the crafts home base. The flight back was uneventful. I am currently working on a way to induce warm air to the carburetor when needed, to hopefully avoid such a situation again. At 4500 ft MSL and the engine still able to produce power, I briefly thought of trying to make it to an uncontrolled field, but decided against it knowing for certain I could make jackson.

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Original NASA ASRS Text

Title: EXPERIMENTAL ACFT HAS PWR LOSS AT CRUISE.

Narrative: WHILE CRUISING AT 4500 FT MSL. I ADDED PWR TO ADJUST MY ALT. I WAS ACTUALLY 100 FT LOWER THAN 4500 AND WANTED TO GET BACK UP. WHEN I PUSHED THE THROTTLE IN, THE ENG FALTERED AND LOST PWR. UPON RETRACTING THE THROTTLE TO THE ORIGINAL SETTING, THE ENG REGAINED THAT PWR, AFTER A COUPLE MORE ATTEMPTS WERE MADE TO ADJUST PWR, I FOUND THAT IF I RETRACTED PWR I COULD NOT GAIN IT BACK. GIVEN THE HIGH HUMIDITY AND THE FACT THAT ALL OF THE ENG MONITORING INSTS WERE NORMAL, I FELT I WAS EXPERIENCING ICE BUILD-UP IN THE INTAKE SYS. NOT HAVING CARB HEAT. I DECIDED TO MAKE AN EMER LNDG AT THE NEAREST RWY WHICH WAS JACKSON, ABOUT 4 MI TO THE E. WITHOUT RADIO, I INTERMITTENTLY ACTIVATED MY ELT AS I DSNDED TO THE ARPT, IN AN ATTEMPT TO ATTRACT ATTN. AS I APCHED THE RWY I PICKED UP THE DEPARTING TFC AND MADE SURE TO STAY CLR AND WAS ABLE TO LAND BTWN DEPARTING AND LNDG ACFT WITHOUT ENDANGERING ANYONE, AND EXITED THE RWY INTO THE GRASS IMMEDIATELY. THE TWR PERSONNEL DID NOT EVEN KNOW I LANDED UNTIL THE FBO CALLED THEM ASKING IF THEY WERE AWARE OF ME. I WENT UP AND SPOKE WITH THEM EXPLAINING MYSELF AS I HAVE DONE HERE. I FEEL THAT THE HIGH HUMIDITY ON THAT PARTICULAR DAY CAUSED ICE BUILDUP IN THE INTAKE SYS. I'VE FLOWN THE ACFT FOR 140 HRS SINCE 1988, AND HAVE HAD NO PROBS AS SUCH, BUT I DON'T RECALL EVERY FLYING IN SUCH HUMID CONDITIONS. THE PLANE WAS STARTED ABOUT 5 MINS AFTER LNDG. IT RAN ROUGH FOR ABOUT THE FIRST 30 SECONDS OF ADDING THROTTLE, WENT BACK DOWN AND ADDED THROTTLE A SECOND TIME. THE ENG ATTAINED AND MAINTAINED ITS NORMAL STATIC RPM, THIS WAS REPEATED 3 TIMES. BECAUSE OF THE HEAT, I PULLED THE ACFT INTO A HANGAR ON THE FIELD, DECOWLED IT, AND GAVE IT A THOROUGH LOOKING OVER, FINDING NOTHING UNUSUAL. I STARTED AND TAXIED THE PLANE OUT AND FLEW IT HOME LATER THAT EVENING WHEN THE TEMP COOLED DOWN. WITH THE TWR'S PERMISSION AND LIGHT SIGNALS I TOOK OFF AND CLBED OVER THE RWY TO 5000 FT MSL. WHEN ALL SEEMED WELL, I WAGGED MY WINGS AND DEPARTED TO THE E FOR METTETAL ARPT, THE CRAFTS HOME BASE. THE FLT BACK WAS UNEVENTFUL. I AM CURRENTLY WORKING ON A WAY TO INDUCE WARM AIR TO THE CARB WHEN NEEDED, TO HOPEFULLY AVOID SUCH A SIT AGAIN. AT 4500 FT MSL AND THE ENG STILL ABLE TO PRODUCE PWR, I BRIEFLY THOUGHT OF TRYING TO MAKE IT TO AN UNCTLED FIELD, BUT DECIDED AGAINST IT KNOWING FOR CERTAIN I COULD MAKE JACKSON.

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.