NTSB Identification: MIA97LA006.
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Accident occurred Saturday, October 19, 1996 in LEXINGTON, TN
Probable Cause Approval Date: 05/30/1997
Aircraft: Cessna 150F, registration: N7102F
Injuries: 2 Serious.

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 initially attempted to takeoff with a slight quartering tailwind, but he aborted the takeoff, then initiated a takeoff into the wind. Takeoff distance calculations showed that 1,315 feet would be required to clear a 50-foot obstacle. The airplane was observed to rotate about 4,300 feet down the 5,000 foot runway, climb to about 150 to 200 feet agl, roll left, then pitch nose down. The airplane impacted the ground nose and left wing low. Examination of the flight control systems revealed no evidence of a preimpact failure or malfunction. Examination of the engine revealed that the No. 4 cylinder exhaust valve was open. Dimensional measurements of the exhaust valve stem and the valve guide revealed that they had less then the minimum clearance as required by the overhaul manual. Review of the engine logbooks revealed that the engine was overhauled by an A & P mechanic in 1988. The overhaul manual indicated that after replacement of the exhaust valve guides, they were to be reamed to size. The engine had accumulated 443.96 hours since overhaul at the time of the accident. A pilot, who had flown the accident airplane on a previous flight, noted excessive rpm drop during the carburetor heat check. The airplane owner had been notified of the excessive rpm drop, but review of the maintenance records did not reflect that engine maintenance was performed.

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

failure of the pilot to abort the takeoff after encountering excessive ground roll, and failure (or inability) of the pilot to obtain/maintain adequate airspeed, which resulted in an inadvertent stall. Factors relating to the accident were: restricted movement of the No. 4 cylinder exhaust valve, due to improper engine overhaul by the previous owner/mechanic, and failure of the current owner to perform maintenance after being advised by a pilot of excessive rpm drop during a carburetor heat check.

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