ASN Wikibase Occurrence # 272962
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| Date: | Thursday 30 March 2000 |
| Time: | |
| Type: |  Bell 206B |
| Owner/operator: | |
| Registration: | ZS-HMB |
| MSN: | 3639 |
| Year of manufacture: | 1982 |
| Fatalities: | Fatalities: 0 / Occupants: 4 |
| Aircraft damage: | |
| Category: | Accident |
| Location: | Crocodile River Gorge (Nelspruit area) -
 South Africa
|
| Phase: | |
| Nature: | |
| Departure airport: | FANS |
| FQMA (Maputo) | |
| Investigating agency: | CAA S.A. |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot accompanied by three passengers was engaged in an international charter flight en route from Nelspruit to Maputo. While flying through the Crocodile Gorge to avoid cloudy conditions at higher levels there was a sudden bang and the helicopter yawed to the left. The pilot applied right rudder pedal to counter act the swing. At the same time the ENG OUT warning light illuminated followed by the ENG OUT Audio warning. With the throttle still at full power the main rotor RPM was decreasing, the helicopter was established in autorotational flight. Due to the terrain limited-landing options were available and the pilot elected to land in an open area on the riverbank. During the descent the pilot noticed that the power turbine rpm was greater than the main rotor rpm. Due to recent recurrent training on type where they had discussed this exact scenario and symptoms he left the engine running until after the landing to maintain tail rotor control. During the descent he also noticed the ENG CHIP warning light illuminating. On landing, one of the main rotor blades severed the tailboom and tail rotor drive shaft. On landing with the throttle still open the pilot observed that the engine Ng was at idle (58%) with the power turbine at 100% and the main rotor rpm at approximately 45% and decreasing. Once the main rotor blades stopped turning all the occupants disembarked uninjured. The main rotor brake was inoperative due to the failure of the input drive shaft coupling from the engine to the main rotor gearbox. PROBABLE CAUSE: The power transferred from the engine by the main drive shaft via the inner coupling to the outer coupling, combined with the relative movement between the two couplings causes the generation of heat.
Accident investigation:
 |
|
Sources:
S.A. CAA
Revision history:
| Date/time | Contributor | Updates |
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