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| Date: | Tuesday 28 May 2024 |
| Time: | |
| Type: | Aéro Services Guépard Guepy 582 |
| Owner/operator: | Private |
| Registration: | 25AAG |
| MSN: | |
| Fatalities: | Fatalities: 1 / Occupants: 1 |
| Other fatalities: | 0 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | near Besançon-Thise Airfield (LFSA) -
 France
|
| Phase: | Initial climb |
| Nature: | Private |
| Departure airport: | Besançon-Thise Airfield (LFSA) |
| Besançon-Thise Airfield (LFSA) | |
| Investigating agency: | BEA |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot lost control of the aircraft at an altitude of approximately 30 meters after takeoff.
The pilot was making his first flight after a long period of grounding lasting more than a year, during which he carried out various maintenance tasks on his microlight. Before takeoff, the pilot did not perform any full-throttle engine tests, according to witnesses.
The bore of the front carburetor exhibited a local irregularity. When applying power for takeoff, the front carburetor slide valve may have become stuck in the upper position ("full throttle" position). When the pilot reduced power during the climb, the difference in position between the slide valves may have caused the two carburetors to become desynchronized. The imbalance between the thrust developed by each of the two pistons may have led to severe vibrations, variations in engine speed, and a reduction in the power delivered by the engine. Witnesses on the ground observed significant variations in engine speed during the flight.
The investigation was unable to explain the trajectory followed by the pilot.
The pilot found himself above a row of trees and a meadow with an upward slope, upstream of the town of Thise. The pilot lost control of the microlight as he began a low turn.
Accident investigation:
 |
|
Sources:
https://bea.aero/en/investigation-reports/notified-events/detail/accident-to-the-microlight-aeroservices-guepy-582-identified-25aag-on-28-05-2024-at-besancon-thise/
https://france3-regions.francetvinfo.fr/bourgogne-franche-comte/doubs/besancon/un-avion-s-ecrase-sur-l-aerodrome-de-besancon-thise-dans-le-doubs-2976857.html
https://www.estrepublicain.fr/faits-divers-justice/2024/05/28/crash-d-un-ulm-un-homme-se-tue-a-thise
https://www.pleinair.net/actualites/item/12358-thise-crash-d-un-ulm-le-pilote-perd-la-vie
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 07-Jun-2024 17:32 | ASN | Added |
| 07-Jun-2024 17:33 | ASN | Updated [Location, Nature, Source, ] |
| 07-Jun-2024 17:35 | ASN | Updated |
| 16-Oct-2025 15:04 | ASN | Updated [Narrative, Accident report, ] |
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