History of Flight
On April 3, 2011, at approximately 1253 Pacific daylight time, an experimental amateur-built Tomei Rans S12 XL airplane, registration N8113N, collided with the ground shortly after takeoff from a private airstrip near Pleasant Grove, California. The certificated sport pilot, who was also the airplane's owner, sustained fatal injuries. The airplane was substantially damaged, including the forward fuselage, empennage, and wing assembly. The flight was conducted under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed.
Witness Observations
A witness who held a pilot certificate and was acquainted with the pilot reported that the accident airplane landed at the private airstrip at about 1150. The witness and the pilot conversed for 30 to 45 minutes, discussing a potential flight to another airstrip south of their location as a flight of two. While performing a run-up, the witness observed the accident airplane depart to the northwest. Shortly after takeoff, as the airplane reached an altitude between 200 and 300 feet above ground level, it appeared to slow down, bank to the left, and subsequently spiraled to the ground. In a separate conversation, the witness stated that the airplane was airborne for about two minutes after engine start.
Aircraft and Engine Information
The airplane was equipped with a 2-stroke Rotax 582 liquid-cooled, 2-cylinder piston engine, serial number 4656067. The engine had accumulated a total time since new of 318.6 hours.
Post-Accident Examination
Examination of the engine revealed evidence of abnormal piston wear. Mechanical scoring and vertical grooves were noted along the forward cylinder walls and forward piston skirt. Both piston rings were intact but seized within their ring lands. The piston wrist pin, wrist pin bearings, and connecting rod were in place with no damage.
Manufacturer Information
A representative of the engine manufacturer stated that the observed cylinder and piston wear and damage signatures were indicative of an in-flight "cold seizure" of the piston. According to the representative, this condition occurs when there is a thermal imbalance between the piston and cylinder, often due to lack of engine warm-up or excessive temperature coolant difference between inlet and outlet. A manufacturer-issued Service Information Letter dated July 1994 addressed the potential for piston seizure, noting that putting a cold engine to hard work without uniform and correct warm-up can cause the piston to expand quicker than the cylinder, minimizing clearance and leading to scuffing and seizure.