GEORGETOWN, CA, USA
N9933N
CESSNA T210N
THE PILOT SAID HE WAS IN CRUISE AT 10,500 FEET WHEN THE OIL PRESSURE WENT TO ZERO AND THE OIL TEMPERATURE ROSE. THE ENGINE QUIT SHORTLY THEREAFTER. THE AIRCRAFT THEN COLLIDED WITH GROUND OBSTRUCTIONS DURING A UPHILL FORCED LANDING ATTEMPT IN MOUNTAINOUS TERRAIN. EXTERNAL EXAMINATION OF THE ENGINE REVEALED THAT THE NUMBER 2 CONNECTING ROD HAD FAILED AND WAS STICKING UP THROUGH THE CASE. INTERNAL EXAMINATION OF THE ENGINE REVEALED THAT THE NUMBER 2 MAIN BEARING HAD SPUN IN THE JOURNAL, WITH SEVERE ABRASION NOTED UNDER THE BEARING INSERTS. THE OIL CHANNEL IN THE NUMBER 2 MAIN BEARING JOURNAL WAS FOUND TOTALLY PLUGGED WITH METAL PARTICLES. PROGRESSIVE HEAT DISCOLORATION AND COMPONENT DISTRESS WAS FOUND DOWNSTREAM IN THE OILING PATH OF THE NUMBER 2 MAIN BEARING. THE ENGINE AND BEARINGS WAS EXAMINED BY A TECHNICAL REPRESENTATIVE FROM CONTINENTAL ENGINES WHO OPINED THAT THE BEARING HAD BEEN INTERMITTENTLY SPINNING ON THE JOURNAL FOR 10 HOURS AND THAT THE FAILURE OF THE NUMBER 2 CONNECTING ROD WAS DUE TO OIL STARVATION CAUSED BY THE RESTRICTIONS IN THE OIL PATH. HE STATED THAT THE MOST LIKELY CAUSE OF THE BEARING SPIN CONDITION WAS UNDER TORQUE OF THE CASE THROUGH BOLTS AT THE NUMBER 2 MAIN BEARING AREA. THE ENGINE WAS OVERHAULED 70 HOURS PRIOR TO THE ACCIDENT.
THE UNDER TORQUE OF THE CRANKCASE THROUGH BOLTS DURING OVERHAUL CAUSING; 1) THE NUMBER 2 MAIN BEARING TO SPIN, 2) THE RESULTANT BLOCKAGE OF THE INTERNAL OIL PASSAGE, AND 3) THE OIL STARVATION INDUCED FAILURE OF THE NUMBER 2 CONNECTING ROD AND CAP. A FACTOR IN THE ACCIDENT WAS THE UNSUITABLE NATURE OF THE TERRAIN WHICH MADE A SUCCESSFUL FORCED LANDING IMPOSSIBLE.
Source: NTSB Aviation Accident Database
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