Covering form of preliminary or final report
| Date of event : | 2020-08-19 |
| Incident number : | CZ-20-0522 |
| Report : | Final report |
| Place of event : | Field 2,8 km NE of Kardašova Řečice |
| Registration mark : | Accident |
| Weight category MTOM: : | <2250 kg |
| Type of operation : | Recreational and sport aviation |
| Plane / SFM : | Airplanes |
| Type of plane / SFM : | ZLÍN Z-43 |
| Health effects of event : | With injury |
| PDF document : | 
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Description:
SUMMARY
Overview
On 19 August 2020, at 16:12, the AAII was notified by RCC Prague, LKJH FOM and then by the Police of the Czech Republic of an air accident of aircraft Z-43, registration mark OK-COE. The female student pilot was conducting a training flight within the airspace when a considerable drop in the engine power output occurred. As it was not possible to continue flying to LKJH, she decided to perform emergency landing on the field she had selected. After the aircraft touchdown on the field with low crop, at the end of landing run, the nose landing gear sank in the water-logged terrain and broke down when the propeller, front part of the aircraft and the right half of the wing touched the ground. The student pilot suffered a minor injury and the aircraft sustained substantial damage in the air accident.
Factual Information
On 19 August 2020, the female student pilot was performing training flights from LKJH. Between 15:07 and 15:47, she was, under instructor’s supervision, training turns and forced landing in accordance with the syllabus included in the CAA-VP-142-3 training programme at the altitude of 300–700 m AGL in the area west of Kardašova Řečice. After they landed, the instructor disembarked and let the student pilot (hereinafter the “student pilot”) conduct a solo flight.
At 15:50, after the instructor disembarked, the student pilot took off from LKJH
RWY 25R without turning off the engine. She continued in the second turn of the right circuit and then ascended to the altitude of 1,000 m at QNH (550 m AGL) in the area east of Kardašova Řečice.
Before she completed one turn in the direction to LKJH, the engine markedly lost power output and did not respond to any changes in the position of controls. The student pilot decided to perform an emergency landing in the terrain. The aircraft was located approx. 10 km NW from LKJH. The student pilot selected a field without a high crop for emergency landing. However, the area was partially water-logged and soggy. Approximately in one third of landing run, the aircraft started sinking in the soil. After about 110m landing run, the nose landing gear leg broke off. The propeller thus touched the ground and the aircraft stopped in a nose down position. Meanwhile, the aircraft rolled to the right and the end of the right half of the wing crashed into the ground. After that, the aircraft again “sat down” on the main landing gear. The student pilot closed the fuel feed, shut off electric power supply, deplaned, and called for help by phone.
Analysis
The student pilot held the necessary qualification and was medically fit for performing the given flight. She had little experience with flying on this type.
Until the engine malfunction, the aircraft was airworthy and in good technical condition. The aircraft airframe was damaged when the aircraft sank into the soggy ground and the right half of the wing touched the ground after the front landing gear leg broke. The fracture was caused by one-off force exertion when the front landing gear sank into the water-logged ground. The force resulted in a bending moment exceeding the breaking and elastic limits of the shock absorber piston rod material.
The aircraft landing weight and the centre of gravity were within the permitted limits and had no impact on the occurrence of the event.
According to the conclusions of chemical analyses of fuel and oil samples, their quality and type were within the prescribed standards. The oil and fuel volumes were also as required.
The weather was suitable for the flight activity and had no effect on the cause of the air accident.
The engine was disassembled in order to identify the cause of its power output loss. Engine dismantling showed that the gear and injecting pump drive was cut off as a result of the vertical shaft cog teeth destruction. The teeth were destroyed because of limited rotary power of the vertical shaft after the fall of the Sc1404 locking pin out of the bearing bushing. The most likely cause of the defect was a loose bearing bushing with a little overlap, which caused the locking pin to drop out. This situation resulted in rotating of the bearing bushing and due to misalignment, the vertical shaft was blocked during rotation and the teeth on the upper part of the vertical (royal) shaft were broken out. The reason for the loss of bearing bushing overlap as against the collector orifice cannot be clearly established on the basis of available information.
Causes
The main cause of the air accident was a technical defect of engine, which caused a loss of power output and necessary emergency landing on the field.
The contributory cause was the fact that the pilot had selected for emergency landing an area that was water-logged where the aircraft was performing its landing run. The nose landing gear sank, which resulted in its breakage and further major damage to the aircraft upon touching the ground.
Attached final report in PDF file is in original Czech language.