NTSB Identification: CHI99LA352.
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Accident occurred Sunday, September 05, 1999 in LEBANON, MO
Probable Cause Approval Date: 03/02/2001
Aircraft: Cessna 150M, registration: N63668
Injuries: 2 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 airplane was in level cruise flight at 2,500 feet msl, 85 knots, 2450 RPM, and heading 020 degrees toward Camdenton, Missouri, when the airplane's engine 'began running rough with RPM drop to 1500-1600.' The pilot said he applied carburetor heat, raised the nose of the airplane to minimize the altitude loss, and started heading toward Lebanon, Missouri. By leaning the mixture, the pilot was 'able to bring the engine RPM up to 1600-1700.' The pilot contacted the approach control at Springfield, Missouri, and informed them of their situation. The pilot said that the RPM began decreasing again. He placed the mixture to full rich, but noticed no change in performance. Then the engine stopped. The pilot said he maintained a 50-55 knot glide until the airplane impacted into a heavily wooded area. Examination of the airplane's engine showed that the shaft supporting the number 3 cylinder rocker arm had broken off. Examination of the remaining airplane systems showed no anomalies.

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

A loss of engine power due to a fractured shaft supporting the number three cylinder rocker arm. A factor relating to this accident was the trees.

Full narrative available

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