A GRUMMAN CHEETAH PVT PLT PERFORMS AN ENG OUT EMER FORCED LNDG ON A RETURN LAND AT FTW; TX.

Narrative

AFTER A NORMAL PREFLT AND PREFLT RUN-UP; I DEPARTED FT WORTH MEACHAM FIELD IN ACFT X; A GRUMMAN AA5A CHEETAH; VIA RWY 16L. TKOF AND CLBOUT WERE NORMAL WITH ENG AND FLT INSTS INDICATING NORMAL OPS. AT APPROX 2000 FT MSL 2 NM S OF FTW; THE ENG BEGAN RUNNING EXTREMELY ROUGH WITH AN INTENSE VIBRATION AND ACCOMPANYING ABNORMAL SOUND FROM THE ENG. PWR WAS IMMEDIATELY REDUCED AND ENG OUT PROCS WERE DEPLOYED (FUEL TANKS SWITCHED; MIXTURE VERIFIED FULL; FUEL PUMP ON). AFTER APPROX 15 SECONDS WITH NO IMPROVEMENT; I CONTACTED FTW MEACHAM TWR; DECLARED AN EMER; INDICATED A ROUGH ENG AND STATED I WAS RETURNING TO THE ARPT. MEACHAM PASSED WIND INFO AND CLRED ME TO LAND ON ANY AVAILABLE RWY. I ALIGNED MYSELF WITH RWY 34R; OPTING TO LAND WITH THE WIND OUT OF THE S AT 8 KTS. ONCE ALIGNED WITH RWY; I CUT OFF ENG AND ON SHORT FINAL; TURNED OFF ELECTRICAL PWR. ACFT TOUCHED DOWN APPROX 2000 FT DOWN THE RWY AND A NORMAL LNDG WAS MADE. ACFT CONTINUED TO ROLL DOWN RWY 34R AND EXITED AND STOPPED ON TXWY A2. AFTER EXITING THE RWY; I TURNED ON ELECTRICAL PWR; AND CONTACTED THE TWR TO INDICATE EVERYTHING WAS OK. THE REASON FOR THE LOSS OF PWR IS STILL TO BE DETERMINED. MOST LIKELY CAUSES INCLUDE SOME FORM OF VALVE FAILURE WITHIN 1 CYLINDER OR A MAGNETO FAILURE (UNLIKELY). OIL PRESSURE REMAINED CONSTANT THROUGHOUT.