Narrative:

At a point approximately twenty minutes from destination; the engine abruptly began running quite rough; with an associated loss of power. The roughness/vibration initially seemed like a serious mechanical failure might have occurred. Soon thereafter; the rough symptoms settled and the engine was running but at a lower power output. I imagined that I might be operating on three of four cylinders.I asked the center for a possible diversion airport and they vectored me toward a nearby private; sod field. But the engine actually returned to 'normal' at some point while looking for the grass field. As I was unable to visually acquire the diversion airport; I chose to continue to my original destination which I recall was about eighteen miles east. While proceeding direct to my destination the engine vacillated between 'normal' and a reduced output at least two more times. The reduction was not particularly rough; but seemed like a significant percent of the power would just 'go away'; probably for only a few seconds at a time; then returning to full power. Fuel tank position seemed irrelevant so I selected the known greatest quantity on the left tank.approximately five miles out I had the runway in sight although I knew reaching it was not 100% assured. So I kept a constant look-out for any available landing site. I checked in on CTAF; stating that I was an emergency aircraft inbound for a straight in approach to the runway. I didn't note any other traffic on frequency; nor did I see any activity yet. At about one mile closer; after the CTAF call; I noted another landing site to my left that appeared more suitable than anything between my present position and the runway. It consisted of a north/south road (unimproved; dry and wide enough with no power lines). The road divided two fields: to the east was a corn field and on the west was a lower crop; perhaps a bean field.shortly after noting this possible landing site; the engine lost power. I clearly was not in a position to make the runway so I immediately turned toward the area described above. I was initially confident that I would have the energy to reach the road and make a right turn to successfully land to the north. Unfortunately the glide performance was not what I expected. Now my greatest concern became avoiding the corn field. It seemed I might be able to keep just enough energy to actually cross the corn field and reach the road. For a moment I was tempted to execute a right turn for the road; however landing straight ahead seemed to be a safer choice. I was determined to maintain flying speed; and keep the aircraft upright throughout the forced landing.the airplane came across the road touching down in a clear area but immediately entered the bean field. The subsequent roll out in the bean field was approximately forty feet. The airplane started to nose over as the bean plants apparently created a massive drag but finally came to rest on all three gears.

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Original NASA ASRS Text

Title: An RV4 pilot landed safely in a bean field after suffering engine failure.

Narrative: At a point approximately twenty minutes from destination; the engine abruptly began running quite rough; with an associated loss of power. The roughness/vibration initially seemed like a serious mechanical failure might have occurred. Soon thereafter; the rough symptoms settled and the engine was running but at a lower power output. I imagined that I might be operating on three of four cylinders.I asked the Center for a possible diversion airport and they vectored me toward a nearby private; sod field. But the engine actually returned to 'normal' at some point while looking for the grass field. As I was unable to visually acquire the diversion airport; I chose to continue to my original destination which I recall was about eighteen miles east. While proceeding direct to my destination the engine vacillated between 'normal' and a reduced output at least two more times. The reduction was not particularly rough; but seemed like a significant percent of the power would just 'go away'; probably for only a few seconds at a time; then returning to full power. Fuel tank position seemed irrelevant so I selected the known greatest quantity on the left tank.Approximately five miles out I had the runway in sight although I knew reaching it was NOT 100% assured. So I kept a constant look-out for any available landing site. I checked in on CTAF; stating that I was an emergency aircraft inbound for a straight in approach to the runway. I didn't note any other traffic on frequency; nor did I see any activity yet. At about one mile closer; after the CTAF call; I noted another landing site to my left that appeared more suitable than anything between my present position and the runway. It consisted of a north/south road (unimproved; dry and wide enough with NO power lines). The road divided two fields: To the east was a corn field and on the west was a lower crop; perhaps a bean field.Shortly after noting this possible landing site; the engine lost power. I clearly was not in a position to make the runway so I immediately turned toward the area described above. I was initially confident that I would have the energy to reach the road and make a right turn to successfully land to the north. Unfortunately the glide performance was not what I expected. Now my greatest concern became avoiding the corn field. It seemed I might be able to keep just enough energy to actually cross the corn field and reach the road. For a moment I was tempted to execute a right turn for the road; however landing straight ahead seemed to be a safer choice. I was determined to maintain flying speed; and keep the aircraft upright throughout the forced landing.The airplane came across the road touching down in a clear area but immediately entered the bean field. The subsequent roll out in the bean field was approximately forty feet. The airplane started to nose over as the bean plants apparently created a massive drag but finally came to rest on all three gears.

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.