What happened
On July 18, 2017, at Poznań Kobylnica (EPPK), an Extra EA 300/L was engaged in glider towing operations for training purposes. The aircraft had completed 15 successful towing cycles over a period of 75 minutes before preparing for a new series of flights. After refueling, the pilot taxied from the fuel station toward the threshold of runway 25, where the gliders were positioned.
Due to the limited visibility from the rear cockpit, the pilot utilized a serpentine taxiing method. While executing a 90-degree turn to align the aircraft perpendicular to the runway, the pilot received a hand signal from the pilot of an S-1 Swift glider indicating readiness. As the pilot applied increased throttle to begin a left turn to align with the glider, the increased airflow caused the cockpit canopy to spontaneously open. The canopy fell onto the right side of the aircraft's fuselage, resulting in damage to the canopy itself, though the frame and hinges remained intact.
The investigation
The investigation focused on the locking mechanism of the Extra EA 300/L canopy. The process for securing the canopy requires the pilot to close the canopy, compress the handle, press the canopy against the fuselage, and then release the handle. A successful lock is indicated by the color red appearing on the inner edge of the frame. The investigation examined the physical state of the hinges and locks, finding no visible cracks, damage, or mechanical jams.
Findings
- The primary cause of the canopy failure was the imprecise closing of the cockpit canopy.
- A contributing factor was the pilot's failure to perform a physical check of the canopy'1s security by attempting to lift it by hand after closing it.
- The pilot was highly experienced and possessed the necessary qualifications for the task.