Covering form of preliminary or final report
| Date of event : | 2020-10-10 |
| Incident number : | CZ-20-0689 |
| Report : | Final report |
| Place of event : | Olomouc airport |
| Registration mark : | Accident |
| Weight category MTOM: : | <2250 kg |
| Type of operation : | Recreational and sport aviation |
| Plane / SFM : | Airplanes |
| Type of plane / SFM : | Zlín Z 526 AFS-V |
| Health effects of event : | Without injury |
| PDF document : | 
|
Description:
SUMMARY
Synopsis
On 10 October 2020, the AAII was notified of an air accident of the ZLÍN Z 526 AFS-V aircraft at LKOL. The pilot was carrying out aerotows of gliders from RWY 27R. During the fourth take-off run phase, at a speed of approx. 80 km∙h-1 (IAS), the main landing gear became unloaded and then retracted. The aircraft pancaked and made a belly landing. The propeller blades were damaged and the engine was brought to forced stall. The pilot was not hurt.
The glider pilot released the towline from the towing aircraft and landed safely at LKOL.
Factual Information
The pilot, flying the Z 526 AFS-V aircraft, was performing a take-off aerotowing of the L-23 SUPER BLANÍK glider from the grassy RWY 27R. The glider was attached to the towing aircraft with a 40-meter towline. During the take-off run phase, at a speed of approx. 80 km∙h-1 (IAS), the landing gear became unloaded and then retracted. The aircraft pancaked and belly-landed on the runway. The aircraft was skidding on the unpaved grassy ground for some 50 m until full stop. In his testimony, the pilot said among other things: “It was my fourth flight with this aircraft today and the previous three were perfectly fine. The same applies to landing after the third flight. As regards the fourth take-off, I can say that it was my fault when controlling the landing gear. I checked the aircraft before the said fourth flight properly and found no visible damage.”
Analyses
During aircraft take-off run in aerotow with a glider, the landing gear legs became unloaded and then retracted because the landing gear control switch was in the "RETRACTED" (N) position. The aircraft still did not have sufficient speed for take-off. Due to pancaking, which followed the landing gear retracting, the propeller came into contact with the ground. The aircraft decelerated, hit the ground and, having been skidding on an unpaved grassy runway for some 50 meters, came to a full stop. The glider crew responded to the critical situation correctly and in time. The instructor released the towline, took a collision avoidance action, and safely landed on RWY 27L.
Conclusions/Causes
The cause of the air accident was an incorrect switching of the landing gear control switch to the “retracted” position before the flight, which resulted in landing gear retraction during a take-off run with a subsequent aircraft impact on the ground.
Attached final report in PDF file is in original Czech language.