Accident Overview
During takeoff, the flight instructor (CFI) and student pilot reported an inability to push the control column forward. The CFI reduced engine power, but the aircraft stalled and subsequently crashed into a lake, coming to rest inverted.
Post-Crash Examination
A post-crash examination of the aircraft revealed that a screwdriver was located near the control tee. The control tee was found to be scratched. Investigators noted a similar event had occurred during a previous flight with the same CFI aboard, but a mechanic's inspection at that time could not determine the reason for the binding control.
Attempts to Replicate
After the accident, multiple attempts to artificially cause binding of the elevator control were unsuccessful. No definitive link between the screwdriver and the control binding was established.
Investigation Status
The investigation focused on the physical evidence but did not determine a conclusive cause for the control column binding. The presence of the screwdriver and the scratches on the control tee were noted as possible contributors, but no causal relationship was confirmed.