What happened
On September 19, 2015, a Cessna 150M, registration N714CW, experienced an engine malfunction during a flight from Clearview Airpark in Westminster, Maryland, to Leesburg Executive Airport in Virginia. Approximately 10 minutes after takeoff, while cruising at 2,500 feet, the pilot noted the engine was not producing full power. The pilot adjusted the flight path toward Davis Airport in Laytonsville, Maryland, as a precaution.
As the flight continued, the engine performance became increasingly sluggish and began running roughly before losing further power. The pilot declared an emergency and identified a landing site in a field. During the approach, the pilot observed electrical wires at the end of the field and attempted a downwind landing in the opposite direction. Due to insufficient altitude to reach the intended site, the pilot landed in an adjacent field planted with mature corn. Upon touchdown, the aircraft flipped over, resulting in substantial damage to the airframe. The pilot was not injured.
The investigation
An FAA inspector examined the wreckage at the scene, noting that the nose landing gear had been sheared off, causing damage to the firewall and engine mounts. Both wing spars were damaged, and the vertical stabilizer was bent. The investigation also revealed damage to the number 4 cylinder and oil streaks on the engine cowling and fuselage.
Detailed examination of the Continental O-200-A engine revealed that the number 4 cylinder had fractured at the barrel portion, approximately two inches from the engine case, completely separating from the bottom portion of the cylinder. The number 4 piston was found to be gouged and missing significant material. Microscopic analysis of the fracture face showed a fatigue crack that originated from a corrosion pit on the outer surface of the cylinder barrel. The piston also showed signs of overstress separation.