ASN Wikibase Occurrence # 214036
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| Date: | Thursday 26 October 1978 |
| Time: | 14:28 |
| Type: |  Bell 206B |
| Owner/operator: | |
| Registration: | VH-FJT |
| MSN: | |
| Fatalities: | Fatalities: 0 / Occupants: 5 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | near Mt Isa, QLD -
 Australia
|
| Phase: | Unknown |
| Nature: | Survey |
| Departure airport: | YBMA |
| YBMA | |
| Investigating agency: | BASI |
| Confidence Rating: |  Accident investigation report completed and information captured |
The helicopter was engaged in an aerial inspection of the Spear Creek area, to the north-northwest of Mt. Isa Airport. Several runs were made over the area, at various heights between 100 and 700 feet above ground level, whilst photographs were taken. A systematic visual inspection pattern was then commenced until, after some five minutes, a sighting of potential interest was made. The pilot commenced to orbit the area, at a height of about 125 feet and at an airspeed of approximately 30 knots.
The pilot's first awareness of a malfunction was a loud bang from the rear of the cabin. This was followed by a muffled grating sound. Because of the helicopter's low height and speed a transition to autorotational flight was not possible. However, the pilot lowered the collective control and then pulled it up again just prior to ground contact. At the same time, he attempted to steer the helicopter between the trees.
The helicopter struck a tree and pivoted through approximately 180 degrees. It then bounced about 15 metres and came to rest with the cabin broken open. There was no fire. The accident was seen by personnel at the Airport and emergency services were alerted.
Examination of the main drive shaft established that the failure sequence was initiated by excessive wear in the forward shaft coupling. This restricted flexibility of the coupling, thereby producing bending loads in the shaft forward flange. Fatigue cracking resulted from the abnormal bending loads and had propagated through some 80 percent of the shaft cross-sectional area before the final overload failure occurred.
The main drive shaft assembly had operated for a total of some 1456 hours. The helicopter maintenance records indicated all required maintenance had been carried out on the assembly. No reason was found for the excessive wear in the forward coupling.
Accident investigation:
 |
|
Sources:
https://www.atsb.gov.au/publications/investigation_reports/1978/aair/197800058/
https://www.atsb.gov.au/media/5226305/197800058.pdf
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 04-Aug-2018 09:33 | Pineapple | Added |
Corrections or additions? ... Edit this accident description
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