TOMBALL, TX, USA
N1ZY
BEECH BE-35M
THE AIRPLANE WAS DAMAGED WHEN IT COLLIDED WITH A FENCE AND A DITCH DURING A FORCED LANDING FOLLOWING A COMPLETE ENGINE FAILURE. INVESTIGATION REVEALED THAT THE NO. 5 PISTON WAS SEVERELY HEAT ERODED WITH PIECES MISSING. THE EROSION ALLOWED EXHAUST VENTING (BLOW BY) INTO THE CASE. THERE WAS SOME EVIDENCE OF PRE-IGNITION ON THE OTHER PISTONS' BUT NOT TO THE EXTENT AS ON NO. 5. IT WAS DETERMINED THAT THE ENGINE WAS 17 HOURS OUT OF A MAJOR OVERHAUL AND HAD BEEN USING AUTO GAS AT THE TIME OF THE ACCIDENT. IT APPEARED THAT THE PISTON EROSION HAD OCCURRED OVER A LONG PERIOD OF TIME.
AN ENGINE FAILURE DUE TO DETONATION AND SUBSEQUENT PISTON OVERTEMPERATURE AND EROSION. A FACTOR RELATED TO THE ACCIDENT WAS THE LACK OF SUITABLE TERRAIN.
Source: NTSB Aviation Accident Database
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