Covering form of preliminary or final report

On 10 August 2019, AAII received a notification of an air accident of the ELLIPSE Spirit ultralight aircraft, identification mark OM-M118, at LKSK. The ultralight aircraft cabin canopy opened during the take-off. The pilot attempted to return by left-hand turn and land on RWY 13. During the turn, the ultralight aircraft decelerated and started falling, which resulted in the pilot’s serious injury and destruction of the ultralight aircraft. The cause of the air accident was the canopy opening during the take-off as a result of opening of the mechanical locks of the canopy. The opened canopy caused a loss of controllability of the ultralight aircraft due to the turbulent airflow around the tailplanes in the wake behind the open canopy.

 

On 10 August 2019, at 07:22, the FRS and later at 07:30, the RCC notified AAII of an air accident of the ELLIPSE Spirit ultralight aircraft, identification mark OM-M118, at LKSK. The ultralight aircraft cabin canopy opened during the take-off. The pilot attempted to return by left-hand turn and land on RWY 13. During the turn, the ultralight aircraft decelerated and started falling. It fell down into the trees at the end of the airport. The air accident resulted in the pilot’s serious injury and destruction of the ultralight aircraft.

On 10 August 2019, the pilot took over the repaired ultralight aircraft, prepared for the flight and took off from RWY 31 at 07:09 to fly from LKSK to LKFR. The cabin canopy opened during the take-off. The ultralight aircraft took off in the middle of the RWY, but then touched down the runway again with all the wheels at the level of the hangar. Nevertheless, the pilot did not interrupt the take-up. The ultralight aircraft took off again and continued to climb. Having flown over the end of the runway, the pilot started making a left turn to land on RWY 13. Shortly before the ultralight aircraft reached the forest cover, 112 metres to the right from which there is the RWY 13 threshold, it began to fall in a negative roll at the altitude of approximately 50 m. During the fall, there was a contact between the aircraft and the trees at the edge of the forest, whose height varied from 8 to 10 m. The vegetation decreased the impact speed of the aircraft. The ultralight aircraft fell over the edge of the vegetation under a great angle with the nose down to the ground and rolled over on its back.

 

The ultralight aircraft had a valid Certificate of airworthiness issued by SFUL SK. The aircraft operation documentation had not been updated to correspond with the factual state of the aircraft.

The pilot held valid LAA CZ and SFUL SK certificates, qualifications for the said flight and a valid medical certificate.

The pilot had not familiarised himself sufficiently with the airfield area and the surrounding areas suitable for performing a forced landing, should such need arise.

The operator had the wing integrated slots taped over which caused the stall speed limit to rise, and it also impaired the aircraft’s manoeuvrability and stability at low speeds.

Prior to maintenance procedures, the pilot had disconnected the brace of the linear electro-mechanism of the canopy control, and did not re-connect the same after the aircraft takeover after the maintenance.

The construction of the side locks was not equipped with mechanisms securing the closed position.

During the event flight, the pilot did not abort the take-off after a spontaneous opening of the canopy locks.

The weather and meteorological conditions at the time of event flight had no effect on the cause of the air accident.

 

The immediate cause of the air accident was the canopy opening during the take-off as a result of opening of the mechanical locks of the canopy.

The joint effects to the accident cause were represented by a chain of events:

• During the whole operation time of the aircraft in question, the pilot had been flying the ultralight aircraft with unreliably functioning side canopy locks.
• The pilot did not connect the brace of the linear electro-mechanism when taking the aircraft over from the maintenance procedure.
• The pilot did not close the rear lock of the canopy to the end stop.
• The loss of controllability of the ultralight aircraft was caused by the turbulent airflow around the tailplanes in the wake behind the open canopy.
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AAII issues no safety recommendations.

Attached final report in PDF file is in original Czech language.