Covering form of preliminary or final report
| Date of event : | 2021-07-29 |
| Incident number : | CZ-21-0476 |
| Report : | Final report |
| Place of event : | LKFR |
| Registration mark : | Accident |
| Weight category MTOM: : | <2250 kg |
| Type of operation : | Recreational and sport aviation |
| Plane / SFM : | Sports flying machines |
| Type of plane / SFM : | MH-46 Eclipse |
| Health effects of event : | With injury |
| PDF document : | 
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Description:
Overview
On 29 July 2021, the AAII received a report of an air accident involving a foreign UL aircraft MH-46 Eclipse in Frýdlant nad Ostravicí where the UL aircraft crashed into the forest, approximately 0.8 km north of LKFR. The pilot was performing a check flight of the UL aircraft from LKFR. After take-off, at an altitude of about 30 m, the pilot noticed a drop in engine power. With the intention of making an emergency landing, he directed the UL aircraft to a grain field, in front of which there was a stand of trees. A frontal impact occurred with the top of one of the trees, which was located in the flight axis in front of the intended emergency landing site. Shortly after impact with the ground, the UL aircraft caught fire. The air accident resulted in the pilot’s serious injury and destruction of the ultralight aircraft.
Factual Information
On 29 July 2021, the test pilot was scheduled to conduct flight tests of a foreign UL aircraft. The pilot participated in a preflight inspection conducted by a technician with the executive officer of the UL aircraft owner. The pilot consulted the executive officer of the UL aircraft owner in regards of matters relating to the operation of the UL aircraft. Together they then carried out a cockpit drill and a technical condition check of the UL aircraft. Two engine tests were performed as part of the preflight checks. During boarding the UL aircraft and performing the prestart operations, the pilot was assisted by the UL aircraft owner’s executive officer who, at the pilot’s request, assisted the pilot with strapping in, opening the fuel tap and adjusting the flaps to the take-off position. At the pre-take-off line, the pilot again performed a short engine test and taxied to the take-off point. A critical situation occurred after take-off at an the altitude of approximately 30 metres when the pilot experienced a drop in engine power. After throttling back to increase speed, the pilot decided to make a forward landing, but he observed a built-up area beyond the end of the runway and also the airport terrain dropping in the direction of the runway. The pilot decided to turn to the right where there was a grain field behind a stand of trees. Since the power unit did not stop working completely and at one point there was a spontaneous short-term increase in power, after the power dropped again, the pilot unsuccessfully attempted to increase the RPMs to gain speed and altitude, with the intention of flying over the woodland and landing in the grain field behind it. However, due to the lack of altitude, the UL aircraft struck the top of a tree and subsequently crashed into the forest growth.
Analysis
The pilot held the necessary qualification and was medically fit for performing the given flight. The pilot had little experience with flying on this type. He performed the pre-start tasks together with another person. He failed to warm up the engine to the prescribed temperature before take-off.
Maintenance and operating records of the UL aircraft and engine were not kept and maintained. The UL aircraft had been issued a special airworthiness certificate for the purpose of flight testing and had valid insurance. For the flight in question, the UL aircraft was loaded with a disproportionately large amount of fuel. Prior to take-off, the engine of the UL aircraft was not at the prescribed temperature.
At the time of take-off, the UL aircraft had a tailwind.
Causes
The cause of the accident was loss of engine power, probably due to overflooding of the engine with fuel (very rich mixture) combined with low operating temperature of the engine cylinder heads. This led to the loss of speed and subsequent crash of the UL aircraft.
A contributing cause of the accident was the effect of tailwind and the probable setting of the flaps to an angle other than that appropriate for take-off.
Attached final report in PDF file is in original Czech language.