Narrative:

I had asked departure for lower when they could, explaining that my WX brief stated the freezing level is at 6000 ft. Phl approach called an aircraft about 35 mi in front of me asking them if they have any icing conditions and they responded 'negative icing.' then another aircraft in the area advised that they were at 7000 ft with negative icing conditions. We continued our flight at 6000 ft and after being given to harrisburg approach, I again asked for lower. Harrisburg approach gave us 5000 ft and we came out of the rain showers west of harrisburg, but still in IMC. After passing muu, the engine started to run rough. I immediately applied carburetor heat. My next scan showed that the RPM was passing 1600 rpms. I deactivated the carburetor heat thinking that I needed the rpms to maintain my altitude. I then notified cleveland approach and asked for an ILS approach into altoona which was about 10 mi in front of us. They advised that altoona was at minimums, but a departing aircraft called and advised that it was really 300 ft and not 200 ft. They gave me vectors to the ILS. I became established and followed the GS and localizer. My training in high performance aircraft told me that 99.9% of engine malfunctions happen when there is a change in settings, so I elected to stay at cruise speed until I had the airport environment in sight. We broke out and I saw the airport at my 11 O'clock position and did an s-turn to get to the runway and also at the time I started backing off on the power and applying carburetor heat with no roughness noted. Unfortunately, this turned out to be a downwind landing and I did not get the mains on the ground until past the 2/3 mark down the runway and immediately stated I would do a go around. I was able to make my crosswind and downwind turns in VMC. I followed the runway lights, until I found myself in IMC again. I then called back to ZOB and advised them of the missed and also that the engine was now running ok. They asked me if I wanted to do another ILS at altoona, and I stated that since the engine was now running ok, that I would like to continue to my destination, but as a precaution I asked what the WX was at johnstown. Approach advised me that johnstown was worse than altoona, but the next airport west was latrobe and it was a lot better. Getting closer to agc, I was turned over to pit approach and was asked if I wanted to land at agc. I responded that since the engine was still running ok, I would like to continue to my destination. I was 'cleared for the approach' and followed the approach course to runway 8. After I came out of the cloud deck, I added looking for the airport to my scan, at which time pit approach called stating I was 100 ft low. I replied, 'correcting' at approximately the same time I saw the REIL's. I entered a left base to runway 8, then final, backing off on the power a little at a time. I made the landing with no problems whatsoever, but once we were down and rolling out, I backed off the last of the power and the engine's propeller stopped. The second try the engine started with no problem and we taxied to the parking spot. The next day, 3 different a&P mechanics all agreed that my problem was carburetor icing. We returned east the next day without any further items of interest. Lessons learned: after talking with a&P mechanics and flight instructors, I learned that I need to apply carburetor heat every 10-15 mins during a flight in similar conditions and also to increase my personal minimums from 500 ft to 1000 ft for departure and arrival airports.

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Original NASA ASRS Text

Title: C182 PLT EXPERIENCES A ROUGH RUNNING ENG AND DIVERTS. AFTER A GAR WITH NORMAL ENG OP, PLT ELECTS TO CONTINUE ON TO THE ORIGINAL DEST. ENG MALFUNCTION WAS ATTRIBUTED TO CARB ICING.

Narrative: I HAD ASKED DEP FOR LOWER WHEN THEY COULD, EXPLAINING THAT MY WX BRIEF STATED THE FREEZING LEVEL IS AT 6000 FT. PHL APCH CALLED AN ACFT ABOUT 35 MI IN FRONT OF ME ASKING THEM IF THEY HAVE ANY ICING CONDITIONS AND THEY RESPONDED 'NEGATIVE ICING.' THEN ANOTHER ACFT IN THE AREA ADVISED THAT THEY WERE AT 7000 FT WITH NEGATIVE ICING CONDITIONS. WE CONTINUED OUR FLT AT 6000 FT AND AFTER BEING GIVEN TO HARRISBURG APCH, I AGAIN ASKED FOR LOWER. HARRISBURG APCH GAVE US 5000 FT AND WE CAME OUT OF THE RAIN SHOWERS W OF HARRISBURG, BUT STILL IN IMC. AFTER PASSING MUU, THE ENG STARTED TO RUN ROUGH. I IMMEDIATELY APPLIED CARB HEAT. MY NEXT SCAN SHOWED THAT THE RPM WAS PASSING 1600 RPMS. I DEACTIVATED THE CARB HEAT THINKING THAT I NEEDED THE RPMS TO MAINTAIN MY ALT. I THEN NOTIFIED CLEVELAND APCH AND ASKED FOR AN ILS APCH INTO ALTOONA WHICH WAS ABOUT 10 MI IN FRONT OF US. THEY ADVISED THAT ALTOONA WAS AT MINIMUMS, BUT A DEPARTING ACFT CALLED AND ADVISED THAT IT WAS REALLY 300 FT AND NOT 200 FT. THEY GAVE ME VECTORS TO THE ILS. I BECAME ESTABLISHED AND FOLLOWED THE GS AND LOC. MY TRAINING IN HIGH PERFORMANCE ACFT TOLD ME THAT 99.9% OF ENG MALFUNCTIONS HAPPEN WHEN THERE IS A CHANGE IN SETTINGS, SO I ELECTED TO STAY AT CRUISE SPD UNTIL I HAD THE ARPT ENVIRONMENT IN SIGHT. WE BROKE OUT AND I SAW THE ARPT AT MY 11 O'CLOCK POS AND DID AN S-TURN TO GET TO THE RWY AND ALSO AT THE TIME I STARTED BACKING OFF ON THE PWR AND APPLYING CARB HEAT WITH NO ROUGHNESS NOTED. UNFORTUNATELY, THIS TURNED OUT TO BE A DOWNWIND LNDG AND I DID NOT GET THE MAINS ON THE GND UNTIL PAST THE 2/3 MARK DOWN THE RWY AND IMMEDIATELY STATED I WOULD DO A GAR. I WAS ABLE TO MAKE MY XWIND AND DOWNWIND TURNS IN VMC. I FOLLOWED THE RWY LIGHTS, UNTIL I FOUND MYSELF IN IMC AGAIN. I THEN CALLED BACK TO ZOB AND ADVISED THEM OF THE MISSED AND ALSO THAT THE ENG WAS NOW RUNNING OK. THEY ASKED ME IF I WANTED TO DO ANOTHER ILS AT ALTOONA, AND I STATED THAT SINCE THE ENG WAS NOW RUNNING OK, THAT I WOULD LIKE TO CONTINUE TO MY DEST, BUT AS A PRECAUTION I ASKED WHAT THE WX WAS AT JOHNSTOWN. APCH ADVISED ME THAT JOHNSTOWN WAS WORSE THAN ALTOONA, BUT THE NEXT ARPT W WAS LATROBE AND IT WAS A LOT BETTER. GETTING CLOSER TO AGC, I WAS TURNED OVER TO PIT APCH AND WAS ASKED IF I WANTED TO LAND AT AGC. I RESPONDED THAT SINCE THE ENG WAS STILL RUNNING OK, I WOULD LIKE TO CONTINUE TO MY DEST. I WAS 'CLRED FOR THE APCH' AND FOLLOWED THE APCH COURSE TO RWY 8. AFTER I CAME OUT OF THE CLOUD DECK, I ADDED LOOKING FOR THE ARPT TO MY SCAN, AT WHICH TIME PIT APCH CALLED STATING I WAS 100 FT LOW. I REPLIED, 'CORRECTING' AT APPROX THE SAME TIME I SAW THE REIL'S. I ENTERED A L BASE TO RWY 8, THEN FINAL, BACKING OFF ON THE PWR A LITTLE AT A TIME. I MADE THE LNDG WITH NO PROBS WHATSOEVER, BUT ONCE WE WERE DOWN AND ROLLING OUT, I BACKED OFF THE LAST OF THE PWR AND THE ENG'S PROP STOPPED. THE SECOND TRY THE ENG STARTED WITH NO PROB AND WE TAXIED TO THE PARKING SPOT. THE NEXT DAY, 3 DIFFERENT A&P MECHS ALL AGREED THAT MY PROB WAS CARB ICING. WE RETURNED E THE NEXT DAY WITHOUT ANY FURTHER ITEMS OF INTEREST. LESSONS LEARNED: AFTER TALKING WITH A&P MECHS AND FLT INSTRUCTORS, I LEARNED THAT I NEED TO APPLY CARB HEAT EVERY 10-15 MINS DURING A FLT IN SIMILAR CONDITIONS AND ALSO TO INCREASE MY PERSONAL MINIMUMS FROM 500 FT TO 1000 FT FOR DEP AND ARR ARPTS.

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.