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| Date: | Wednesday 19 August 2009 |
| Time: | morning |
| Type: |  Aérospatiale AS 350B |
| Owner/operator: | Magyar Légimentő Nonprofit Kft. |
| Registration: | HA-BDC |
| MSN: | 1715 |
| Year of manufacture: | 1983 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Other fatalities: | 0 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Balatonfüred -
 Hungary
|
| Phase: | Take off |
| Nature: | Calibration/Inspection |
| Departure airport: | Balatonfüred |
| Investigating agency: | TSB Hungary |
| Confidence Rating: |  Accident investigation report completed and information captured |
Rolled over during engine testing 19.8.2009 at Balatonfured, Hungary; cause reported in contemporary newspaper reports as ground resonance.
3.1 Factual findings directly related to the occurrence
The prerequisite for starting is the securing of the control stick and the collective lever. According to the witness, this happened (but the securing was presumably not perfect).
After the helicopter pilot increased the main rotor speed, the vibration may have caused the securing head of the collective lever to slip out of the locking plate, thereby allowing the collective lever to rise on its own. This increased the forces, torques, and harmonic imbalance, which may have led to the final development of the aviation incident.
3.2 Factual findings indirectly related to the occurrence
When the helicopter reached the critical movement position, the mechanics fell backward, which reduced the mass burdening the left side of the aircraft.
Due to the secured flight controls, the pilot could only intervene with coarse control inputs. It is highly probable that these factors collectively caused the aviation incident.
Accident investigation:
 |
|
Sources:
1. https://www.veol.hu/cimlapon/felborult-egy-mentohelikopter-balatonfureden-frissitve-uj-informaciok-kepgaleria-1348896/
2. http://helihub.com/2009/08/19/19-aug-09-ha-bdc-eurocopter-as350-lake-balaton-hungary/
3. http://www.kbsz.hu/j25/dokumentumok/2009-192-4P.pdf
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 20-Aug-2009 02:13 | Bender4ever | Added |
| 20-Aug-2009 03:23 | bender4ever | Updated |
| 21-Aug-2009 07:58 | snoopy55 | Updated |
| 21-Aug-2009 12:24 | RobertMB | Updated |
| 21-Aug-2009 12:37 | Bender4ever | Updated |
| 22-Aug-2009 01:24 | Bender4ever | Updated |
| 19-Jul-2014 00:42 | Dr. John Smith | Updated [Time, Total fatalities, Other fatalities, Departure airport, Source, Damage, Narrative, ] |
| 26-Sep-2025 18:51 | HanayoPlus | Updated [Operator, Total occupants, Source, Narrative, ] |
| 26-Sep-2025 18:53 | ASN | Updated [Departure airport, Narrative, Accident report, ] |
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