Narrative:

I planned on flying back home yesterday afternoon. Preflight good; started up fine; back taxied to the runway. Good run-up; everything as expected. Took off and made right turn to head north back home. Kept the climb at sixty mph to 2500 ft since it was a bit bumpy down low and the landing options are limited over downtown. I'd just found a nice emergency field off the left side; reached for the throttle to power back and level off -- hadn't touched it yet when suddenly power went down from 2500 RPM to 2000 RPM and the engine sounded sick -- very sick -- as if it were a lawn mower running on bad gas. I glanced at oil pressure; looked for the field; then decided to do a 180 to see how far it was back to the airport. The engine was still putting out some power -- but barely. I had the handheld radio set to 122.800. Announced: 'returning to airport; loss of power; clear the runway' (there was a C172 at the fuel pump that just started after I taxied out -- I never heard him make any calls so didn't know where he was).I looked ahead -- plenty of altitude with this amount of power. If it died between here and there I'd make the river. I didn't touch the throttle until I was two miles out. I was over 1200 ft AGL. I reduced the throttle slightly and it went nearly to idle. I slipped aggressively (very aggressively -- this airplane will fly sideways with enough aileron and counter-rudder) and was still pretty high. I kept the slip in until I was about five feet above the pavement; one third the way down the runway; then wheelied it on the upwind side (when I departed there was a direct crosswind varying from 6-10 KTS. I couldn't see the sock before I landed; but really didn't care).I rolled on one wheel for about 400 ft (I was doing about seventy when I touched down); and kept the weight on the upwind wheel. When the lift decayed I kept the tail up. Eventually both mains were down and I held some brake. I wheeled a long way; but actually only used about 1000 ft of runway. The combination brake and wheel landing allowed me to brake fairly heavily. I pulled the throttle completely to idle -- the engine continued to run; but unevenly. There was no possibility of go around and the end of runway 23 has a nice tall road berm about fifty feet above the runway. I had plenty of runway left once I touched down. I taxied in; parked in front of the hangar; and ran it up -- lots of unburned fuel smell. The FBO owner and a mechanic came out -- we pulled the cowling off. Sure enough; number one plug on the left front cylinder was hanging out in space. They'll repair it there and I'll bring it back home later this week. Bottom line: training took over. As soon as I heard the power change I had my field in sight; did a turn to lose altitude. When I knew I had residual power; made for the airport; kept it high; had an out if the airport wasn't made; and slipped aggressively and wheelied when it was the only option. Practice engine outs; practice slips; and make sure you know how your airplane will fly at different reduced power settings.

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Original NASA ASRS Text

Title: Climbing through 2500 FT departing an uncontrolled airport a Bellanca pilot found his engine performing 'as if it were a lawn mower running on bad gas'. A successful return to the airport was completed.

Narrative: I planned on flying back home yesterday afternoon. Preflight good; started up fine; back taxied to the runway. Good run-up; everything as expected. Took off and made right turn to head north back home. Kept the climb at sixty MPH to 2500 FT since it was a bit bumpy down low and the landing options are limited over downtown. I'd just found a nice emergency field off the left side; reached for the throttle to power back and level off -- hadn't touched it yet when suddenly power went down from 2500 RPM to 2000 RPM and the engine sounded sick -- very sick -- as if it were a lawn mower running on bad gas. I glanced at oil pressure; looked for the field; then decided to do a 180 to see how far it was back to the airport. The engine was still putting out some power -- but barely. I had the handheld radio set to 122.800. Announced: 'Returning to Airport; Loss of power; clear the runway' (there was a C172 at the fuel pump that just started after I taxied out -- I never heard him make any calls so didn't know where he was).I looked ahead -- plenty of altitude with this amount of power. If it died between here and there I'd make the river. I didn't touch the throttle until I was two miles out. I was over 1200 FT AGL. I reduced the throttle slightly and it went nearly to idle. I slipped aggressively (very aggressively -- this airplane will fly sideways with enough aileron and counter-rudder) and was still pretty high. I kept the slip in until I was about five feet above the pavement; one third the way down the runway; then wheelied it on the upwind side (When I departed there was a direct crosswind varying from 6-10 KTS. I couldn't see the sock before I landed; but really didn't care).I rolled on one wheel for about 400 FT (I was doing about seventy when I touched down); and kept the weight on the upwind wheel. When the lift decayed I kept the tail up. Eventually both mains were down and I held some brake. I wheeled a long way; but actually only used about 1000 FT of runway. The combination brake and wheel landing allowed me to brake fairly heavily. I pulled the throttle completely to idle -- the engine continued to run; but unevenly. There was no possibility of go around and the end of Runway 23 has a nice tall road berm about fifty feet above the runway. I had plenty of runway left once I touched down. I taxied in; parked in front of the hangar; and ran it up -- lots of unburned fuel smell. The FBO owner and a mechanic came out -- we pulled the cowling off. Sure enough; number one plug on the left front cylinder was hanging out in space. They'll repair it there and I'll bring it back home later this week. Bottom line: Training took over. As soon as I heard the power change I had my field in sight; did a turn to lose altitude. When I knew I had residual power; made for the airport; kept it high; had an out if the airport wasn't made; and slipped aggressively and wheelied when it was the only option. Practice engine outs; practice slips; and make sure you know how your airplane will fly at different reduced power settings.

Data retrieved from NASA's ASRS site as of April 2012 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.