NTSB Identification: ATL91LA113.
The docket is stored on NTSB microfiche number 45059.
Accident occurred Monday, June 17, 1991 in CAMILLA, GA
Probable Cause Approval Date: 03/31/1993
Aircraft: Rockwell S-2R, registration: N8549V
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE PILOT REPORTED THAT SHORTLY AFTER TAKEOFF, THE ENGINE SHUDDERED VIOLENTLY, THEN QUIT. THE AIRPLANE WAS FORCE LANDED STRAIGHT AHEAD, AND WAS SUBSTANTIALLY DAMAGED BY THE ENSUING COLLISION WITH TREES. POST-CRASH INSPECTION OF THE ENGINE REVEALED THAT THE SPARK PLUGS WERE BADLY CARBON FOULED. NO COMPRESSION WAS OBSERVED ON THE NUMBER ONE CYLINDER, AND COMPRESSION ON THE REMAINING CYLINDERS WAS ONLY 'FAIR.' DISASSEMBLY OF THE NUMBER ONE CYLINDER REVEALED THAT THE EXHAUST VALVE AND SEAT WERE PARTIALLY BURNED. A HAMMER WAS REQUIRED TO REMOVE THE VALVE FROM THE CYLINDER. THE PISTON WAS BADLY CARBONED. A MECHANIC REPORTED THAT THE OPERATOR WAS USING AUTOMOTIVE GASOLINE IN THIS AIRPLANE, WITHOUT AN STC FOR ITS USE.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

RESTRICTED EXHAUST VALVE MOVEMENT, LOW CYLINDER COMPRESSION, AND FOULING OF THE ENGINE SPARK PLUGS, WHICH RESULTED IN THE LOSS OF ENGINE POWER. FACTORS WERE THE IMPROPER SERVICING OF THE AIRCRAFT, AND THE USE OF AN IMPROPER FUEL GRADE.

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