NTSB Identification: NYC97LA035.
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Accident occurred Friday, December 20, 1996 in LEXINGTON, KY
Probable Cause Approval Date: 10/31/1997
Aircraft: Cessna T210M, registration: N732UH
Injuries: 1 Minor,4 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 Cessna 210 was cruising at 11,000 ft at night, when the engine began to run rough & lose power. The pilots attempted to fly to an airport with suitable services, but all engine power was lost. The pilots then performed a forced landing on a divided highway. During the landing, two vehicles were struck. Examination of the airplane & engine revealed oil on the underside of the fuselage & a hole on the top of the engine case. Further examination revealed the #5 exhaust valve guide had fractured just below the flange that seated the guide into the cylinder head, with evidence of fatigue. The #5 exhaust valve was fractured between the valve head & stem; but the cause of this fracture could not be determine due to impact damage to the fractured surfaces. The #5 intake valve was also partially broken, but fracture of this valve appeared to have been from overload, due to impact with debris inside the cylinder. Also, the #5 piston crown was found mutilated, & a hole was broken through the crown to the interior. Additionally, the main bearings and connecting rod bearings were damaged due to a lack of lubrication, and the #2 and #4 connecting rods had failed.

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

failure of #5 exhaust valve and/or #5 exhaust valve guide, which resulted in a progressive engine failure (debris puncturing the #5 piston crown, exhaust gasses entering the crankcase, loss of oil through the breather system, oil exhaustion, and subsequent damage to the engine bearings and connecting rods). Darkness and obstructions (vehicles) in the emergency landing area were related factors.

Full narrative available

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