What happened
On June 4, 2020, a commercial sightseeing flight was underway near Leśna Podlaska when the pilot experienced a sudden loss of climb capability. After taking off from a nearby meadow at approximately 19:20 LMT, the Nucleon WRC Cabrio 42 UL-PPGG “DUDE/K” reached an altitude of 15 to 20 meters. Despite the pilot applying maximum engine power, the aircraft began to descend.
Observing low-voltage power lines approximately 100 meters ahead in the flight path, the pilot attempted an emergency landing. The aircraft struck uneven, tall grass at the edge of the meadow, causing the trike to overturn onto its left side. The impact ruptured the fuel tank, triggering a fire that engulfed the aircraft and the occupants. Both the pilot and the passenger sustained serious injuries (burns). While the pilot was transported to a hospital in Biała Podlaska, the passenger was airlifted to a specialized facility in Łęczna, where they later succumbed to their injuries.
The investigation
The PKBWL investigation focused on the mechanical integrity of the propulsion system and the maintenance history of the aircraft. Investigators examined the wreckage of the trike, which was an amateur-built construction. The examination revealed that the engine, a Honda Silver Wing 592cc, had become detached from the frame due to the fire.
Technical analysis of the drive system uncovered evidence of substandard maintenance and unauthorized modifications. Investigators found that various components had been repaired using low-quality methods, including the use of mismatched bolts and improper welding. Notably, recent repairs performed by third parties had interfered with the ability to properly adjust the tension of the drive belt.
Findings
- The primary cause of the accident was the slipping of the V-belt in the drive system, which resulted in a significant reduction of power being transmitted to the propeller.
- Improperly executed repairs by unqualified individuals prevented the necessary adjustment of the drive belt tension.
- The aircraft was an unregistered, amateur-built construction that had not been reported to the Civil Aviation Authority (ULC).
- The pilot had previously attempted to manage belt slippage using aftermarket anti-slip products rather than addressing the underlying mechanical issues.
- The landing site consisted of highly uneven terrain covered in tall grass, which contributed to the severity of the impact.