Middlesboro, KY, USA
N6651F
CESSNA 150F
During a period of 6 months, a major engine overhaul and annual inspection was being performed on the pilot's airplane. The work was being performed by the pilot's friend, who was an airframe and powerplant mechanic with an inspector authorization. The accident flight was the first flight after the work was completed. About 10 minutes after departure, the engine began vibrating and lost all power during cruise flight. The major overhaul had included the installation of new cylinders. Proper installation of the new cylinders required that the exhaust valve rocker arms have a small orifice to allow oil to pass and lubricate the valves. The intake valve rocker arms did not have an orifice. Examination of the accident engine revealed that the No. 1 cylinder intake valve was stuck open, and exhibited features consistent with oil starvation. Further examination revealed that the No. 1 cylinder had an intake rocker arm (no orifices) on both the intake and exhaust valves. The No. 3 cylinder had an exhaust valve rocker arm (with orifice) on both the intake and exhaust valves. Review of a make and model engine overhaul manual revealed a caution, noting that the exhaust valve rocker arms have an orifice. Further examination of the cylinder did not reveal any additional mechanical anomalies.
On March 13, 2008, about 1520 eastern daylight time, a Cessna 150F, N6651F, was substantially damaged during a forced landing, following a total loss of engine power in cruise flight near Middlesboro, Kentucky. The certificated commercial pilot was seriously injured. No flight plan was filed for the personal flight conducted under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the flight that departed Middlesboro-Bell County Airport (1A6), Middlesboro, Kentucky; destined for Pike County Airport (PBX), Pikeville, Kentucky. The pilot owned and operated the airplane. He stated that the airplane was based at PBX, but had been at 1A6 for about 6 months, while undergoing a major engine overhaul and annual inspection. The work was being performed by the pilot's friend, who was an airframe and powerplant mechanic with an inspector authorization. The accident flight was the first flight after the work was completed. The pilot was attempting to ferry the airplane back to PBX. About 10 minutes after departure, the engine began vibrating and lost all power during cruise flight. The pilot attempted a forced landing; however, the airplane struck utility wires. The airplane then pitched up, descended inverted, and impacted the ground. The airplane was equipped with a Teledyne Continental Motors (TCM) O-200, 100-horsepower engine. The major overhaul included the installation of Airmotive Engineering Corporation (AEC) cylinders. According to a Federal Aviation Administration (FAA) inspector, the exhaust valve rocker arms, for cylinders on that model engine, had a small orifice to allow oil to pass and lubricate the valves. The intake valve rocker arms did not have an orifice. Examination of the accident engine by the FAA inspector revealed that the No. 1 cylinder intake valve was stuck open, and exhibited features consistent with oil starvation. Further examination revealed that the No. 1 cylinder had an intake rocker arm (no orifices) on both the intake and exhaust valves. The No. 3 cylinder had an exhaust valve rocker arm (with orifice) on both the intake and exhaust valves. Review of a TCM overhaul manual for the O-200 model engine revealed, "CAUTION...Exhaust rocker has an oil orifice in the valve stem end for valve stem lubrication." Further examination of the No. 1 cylinder, at the cylinder manufacturer, under the supervision of an FAA inspector, did not reveal any additional mechanical anomalies with the cylinder. The reported weather at K1A6, at 1515, was: wind from 180 degrees at 15 knots, gusting to 19 knots; visibility 10 miles; scattered clouds at 9,000 feet; temperature 22 degrees Celsius (C); dew point 4 degrees C; altimeter 29.86 inches of mercury.
The mechanic's improper maintenance installation of the No. 1 cylinder rocker arms which led to oil starvation and a loss of engine power.
Source: NTSB Aviation Accident Database
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