Narrative:

During descent from 6500 ft to pattern altitude, passing through 3800 ft at approximately a 300 FPM descent, the engine started running rough. I immediately pitched for best glide, went through emergency checklist, mixture rich, full throttle, magnetos both, etc. Engine power was intermittent, as if low fuel. Fuel was more than adequate, however, with about 20 gallons left at destination. Engine RPM dropped by about 200, but I continued on to make the field. Syracuse was my destination. I decided not to do a magneto check mid-air as I was so close to the airport and did not want to risk shutting down the engine. I asked approach control for a short approach which was approved. He asked if I wanted the emergency equipment. Receding to many NTSB reports about proud, invulnerable pilots, I said sure, get the trucks. I landed safely and parked the airplane. I made a report to the ATC supervisor and to rochester FSDO the following day. At the maintenance FBO they removed 8 fouled (badly fouled) plugs, and reset the mixture control, which was the source of the problem. (Ps: I leaned at altitude as best as I could). The mixture was way rich prior to this maintenance. On the ground, the engine was real rough, airplane shaking during the magneto check, with a 200-250 RPM drop. The mechanic noted that tigers are notorious for running rich and fouling. It was quite a disturbing experience with the thought of not making the field and not having a suitable landing site, over a city at night. I was alert however, calm, and took the necessary actions, ie: fuel pump on, mixture adjustment, best glide, short approach, etc. There were no contribution of human factors, ie, fatigue, etc.

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Original NASA ASRS Text

Title: EMER GND EQUIP CALLED OUT FOR SMA WITH ENG PROB IN A NIGHT OP.

Narrative: DURING DSCNT FROM 6500 FT TO PATTERN ALT, PASSING THROUGH 3800 FT AT APPROX A 300 FPM DSCNT, THE ENG STARTED RUNNING ROUGH. I IMMEDIATELY PITCHED FOR BEST GLIDE, WENT THROUGH EMER CHKLIST, MIXTURE RICH, FULL THROTTLE, MAGNETOS BOTH, ETC. ENG PWR WAS INTERMITTENT, AS IF LOW FUEL. FUEL WAS MORE THAN ADEQUATE, HOWEVER, WITH ABOUT 20 GALLONS LEFT AT DEST. ENG RPM DROPPED BY ABOUT 200, BUT I CONTINUED ON TO MAKE THE FIELD. SYRACUSE WAS MY DEST. I DECIDED NOT TO DO A MAGNETO CHK MID-AIR AS I WAS SO CLOSE TO THE ARPT AND DID NOT WANT TO RISK SHUTTING DOWN THE ENG. I ASKED APCH CTL FOR A SHORT APCH WHICH WAS APPROVED. HE ASKED IF I WANTED THE EMER EQUIP. RECEDING TO MANY NTSB RPTS ABOUT PROUD, INVULNERABLE PLTS, I SAID SURE, GET THE TRUCKS. I LANDED SAFELY AND PARKED THE AIRPLANE. I MADE A RPT TO THE ATC SUPVR AND TO ROCHESTER FSDO THE FOLLOWING DAY. AT THE MAINT FBO THEY REMOVED 8 FOULED (BADLY FOULED) PLUGS, AND RESET THE MIXTURE CTL, WHICH WAS THE SOURCE OF THE PROB. (PS: I LEANED AT ALT AS BEST AS I COULD). THE MIXTURE WAS WAY RICH PRIOR TO THIS MAINT. ON THE GND, THE ENG WAS REAL ROUGH, AIRPLANE SHAKING DURING THE MAGNETO CHK, WITH A 200-250 RPM DROP. THE MECH NOTED THAT TIGERS ARE NOTORIOUS FOR RUNNING RICH AND FOULING. IT WAS QUITE A DISTURBING EXPERIENCE WITH THE THOUGHT OF NOT MAKING THE FIELD AND NOT HAVING A SUITABLE LNDG SITE, OVER A CITY AT NIGHT. I WAS ALERT HOWEVER, CALM, AND TOOK THE NECESSARY ACTIONS, IE: FUEL PUMP ON, MIXTURE ADJUSTMENT, BEST GLIDE, SHORT APCH, ETC. THERE WERE NO CONTRIBUTION OF HUMAN FACTORS, IE, FATIGUE, ETC.

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.