Narrative:

I flew from tcl to F85 without a problem. Several hours later (after refueling and doing a preflight) I departed F89 en route to tcl. I was flying my 1989 RV3A. Some 25-30 mins into the flight ZME instructed me to contact jackson, ms, approach. I did, and they acknowledged. I was at 5500 ft in relatively smooth air. Good visibility and all gauges in the green. Without warning, I experienced severe engine roughness. I couldn't read the gauges and the airplane was bucking significantly. Within seconds I: 1) closed the throttle and 2) told approach that I had rather severe engine roughness and needed to make a precautionary landing at the nearest available airport. They told me raymond was at my 1 or 2 O'clock and about 10 mi. They asked if I needed vectors. I reported that I was going to raymond and that I would need vectors since I couldn't read my vertical compass which was virtually spinning (no gyros available). They gave vectors and I reported raymond in sight. They were talking with raymond and told me there was no traffic. They told me I could land straight in but because I was in a taildragger and had sufficient altitude, I elected to do a downwind and land into the wind. I asked for the airport frequency (unicom), but approach told me to stay with them. I landed without incident. Fire and police arrived within mins. By the time I landed, the engine was idling smoothly. We checked fuel, engine and couldn't find anything. Run-ups and test flts did not duplicate the problem. I did not declare an emergency and I remained on approach frequency per their request. I flew the pattern due to wind conditions. I believe everyone acted appropriately under the circumstances. Approach was a real help.

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Original NASA ASRS Text

Title: HOME BUILT ACFT SUFFERS EXTREME ENG VIBRATION. PLT GETS VECTOR TO NEAREST ARPT FROM JACKSON APCH CTLR. POSTFLT INSPECTION AND TEST FLT FAILED TO REVEAL FURTHER SYMPTOMS. A CASE OF POSSIBLE FUEL CONTAMINATION FROM REFUELING AT F89 ARPT, WINNSBORO, LA.

Narrative: I FLEW FROM TCL TO F85 WITHOUT A PROB. SEVERAL HRS LATER (AFTER REFUELING AND DOING A PREFLT) I DEPARTED F89 ENRTE TO TCL. I WAS FLYING MY 1989 RV3A. SOME 25-30 MINS INTO THE FLT ZME INSTRUCTED ME TO CONTACT JACKSON, MS, APCH. I DID, AND THEY ACKNOWLEDGED. I WAS AT 5500 FT IN RELATIVELY SMOOTH AIR. GOOD VISIBILITY AND ALL GAUGES IN THE GREEN. WITHOUT WARNING, I EXPERIENCED SEVERE ENG ROUGHNESS. I COULDN'T READ THE GAUGES AND THE AIRPLANE WAS BUCKING SIGNIFICANTLY. WITHIN SECONDS I: 1) CLOSED THE THROTTLE AND 2) TOLD APCH THAT I HAD RATHER SEVERE ENG ROUGHNESS AND NEEDED TO MAKE A PRECAUTIONARY LNDG AT THE NEAREST AVAILABLE ARPT. THEY TOLD ME RAYMOND WAS AT MY 1 OR 2 O'CLOCK AND ABOUT 10 MI. THEY ASKED IF I NEEDED VECTORS. I RPTED THAT I WAS GOING TO RAYMOND AND THAT I WOULD NEED VECTORS SINCE I COULDN'T READ MY VERT COMPASS WHICH WAS VIRTUALLY SPINNING (NO GYROS AVAILABLE). THEY GAVE VECTORS AND I RPTED RAYMOND IN SIGHT. THEY WERE TALKING WITH RAYMOND AND TOLD ME THERE WAS NO TFC. THEY TOLD ME I COULD LAND STRAIGHT IN BUT BECAUSE I WAS IN A TAILDRAGGER AND HAD SUFFICIENT ALT, I ELECTED TO DO A DOWNWIND AND LAND INTO THE WIND. I ASKED FOR THE ARPT FREQ (UNICOM), BUT APCH TOLD ME TO STAY WITH THEM. I LANDED WITHOUT INCIDENT. FIRE AND POLICE ARRIVED WITHIN MINS. BY THE TIME I LANDED, THE ENG WAS IDLING SMOOTHLY. WE CHKED FUEL, ENG AND COULDN'T FIND ANYTHING. RUN-UPS AND TEST FLTS DID NOT DUPLICATE THE PROB. I DID NOT DECLARE AN EMER AND I REMAINED ON APCH FREQ PER THEIR REQUEST. I FLEW THE PATTERN DUE TO WIND CONDITIONS. I BELIEVE EVERYONE ACTED APPROPRIATELY UNDER THE CIRCUMSTANCES. APCH WAS A REAL HELP.

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.