Primary finding
Probable cause
The total loss of engine power due to an out-of-temperature seizure of the PTO cylinder.
Investigator assessment
Analysis narrative
The pilot reported the engine lost power shortly after takeoff, while at an altitude of about 900 ft. The pilot established best glide speed and attempted to restart the engine several times; however, the engine did not regain power. The pilot then performed a forced landing. During the forced landing, the airplane impacted a tree followed by terrain and sustained substantial damage to the wings and fuselage. Postaccident examination of the two-stroke engine revealed that the power take-off (PTO) cylinder had significant scoring along the cylinder walls, which was consistent with the cylinder being subjected to an out-of-temperature seizure. No further anomalies or mechanical failures were observed that would have prevented normal operation. Given that the visible signatures of a hot seizure and a cold seizure of a cylinder are the same, the type of seizure could not be determined with the available information.
Source record
Factual narrative
On August 4, 2023, about 1030 eastern daylight time, an experimental amateur-built Challenger II, N906WV, was substantially damaged when it was involved in an accident in Port Orange, Florida. The pilot sustained serious injuries and the passenger incurred minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot and passenger departed Spruce Creek Fly-In (7FL6), Port Orange, Florida, for Deland Municipal Airport (DED), DeLand, Florida. Shortly after departure, when the airplane reached about 900 ft above ground level, the engine lost power. The pilot established best glide speed and attempted to restart the engine several times; however, the engine did not regain power. The pilot performed a forced landing, during which the airplane impacted a tree and terrain. Examination of the wreckage at the accident site by a Federal Aviation Administration inspector revealed that the wreckage came to rest inverted in a residential area about 2 miles from 7FL6. Examination of the airplane revealed that the fuselage and wings sustained substantial damage. Postaccident examination of the two-cylinder, two-stroke engine revealed that PTO cylinder displayed significant scoring along the cylinder walls, consistent with the cylinder and piston being subjected to an out-of-temperature seize condition. An examination of the coolant pump, radiator, and coolant hoses revealed no anomalies that would have prevented normal operation of the coolant system. The radiator was noted to have adjustable louvers to facilitate changing the amount of cooling air flowing through the radiator fins. The louvers were noted to be near the fully closed position. The magneto cylinder and the rest of the engine displayed normal operating signatures. The examination of the airframe revealed no anomalies or mechanical failures that would have precluded normal operation.