What happened
On September 8, 2019, a flight student was conducting training in an ultra-light aircraft, a Flight Design CTSW with registration OH-U552. The flight began at Eura aerodrome, traveling to Turku for several circuits and a break. Following several legs of the flight involving Tampere-Pirkkala and Turku, the student decided to perform a solo cross-country flight back to Eura.
During the final approach to runway 11 at Eura, the aircraft experienced a sudden loss of altitude. The aircraft struck the left edge of the runway with significant force, causing a bounce. In an attempt to recover, the student applied full power and pulled back on the control stick. This maneuver caused the nose to pitch up abruptly, leading to a loss of airspeed and a subsequent stall. The aircraft then impacted a wooded area adjacent to the airfield, resulting in extensive damage to the airframe.
The investigation
The OTKES investigation examined the aircraft's performance characteristics, the student's training progress, and the sequence of events leading to the loss of control. The investigation looked into the handling qualities of the Flight Design CTSW, specifically noting its high power-to-weight ratio and the significant pitch-up tendency when power is added during a landing approach. Investigators also reviewed the student's flight hours, noting that the student had accumulated 5 hours and 20 minutes of flight time and 12 landings on the day of the accident.
Findings
- The primary cause of the accident was the pilot's improper control inputs during a recovery attempt following a heavy touchdown.
- The Flight Design CTSW has a high power-to-weight ratio and a significant tendency to pitch its nose up when full power is applied during a landing configuration.
- The aircraft features a short nose design that limits the pilot's view of the aircraft's attitude.
- The student's decision to pull back on the stick while applying full power caused the aircraft to enter a stall.
- The student was performing the flight solo, which altered the aircraft's handling characteristics compared to dual instruction.