ASN Wikibase Occurrence # 209031
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| Date: | Tuesday 15 August 1995 |
| Time: | 10:30 |
| Type: |  Bell 412 |
| Owner/operator: | |
| Registration: | VH-HRS |
| MSN: | 33118 |
| Fatalities: | Fatalities: 0 / Occupants: |
| Aircraft damage: | Minor |
| Location: | Maitland, NSW -
 Australia
|
| Phase: | Landing |
| Nature: | Ambulance |
| Departure airport: | Newcastle, NSW |
| Newcastle, NSW | |
| Investigating agency: | BASI |
| Confidence Rating: |  Accident investigation report completed and information captured |
The helicopter had undergone a maintenance check which included changing both forward and aft coupling assemblies of the main driveshaft and the forward boot assembly. Prior to release for service, vibration monitoring tests were carried out on the ground and during flight. On the final flight, whilst climbing to 4,000 ft in preparation for a descent test, the maintenance crew observed an increase in longitudinal vibration of the main driveshaft. On reaching 4,000 ft, there was a noticeable grinding noise and all power to the main rotor was lost. Following the driveshaft failure, the pilot carried out an autorotation into the only available open field. The field initially appeared flat but as the helicopter approached the ground level, the pilot saw that it was undulating and sloped upwards in the direction of his approach. The pilot was unable to correct for this in time to avoid a heavy landing. A coupling is fitted to each end of the driveshaft. Each coupling is a splined unit packed with grease as a lubricant between its inner and outer components. A rubber boot assembly bolts to the outer coupling to contain the grease as the assembly rotates. An O-ring packing is retained in a groove in the boot as a seal between the boot and the outer coupling. Investigation found that the main driveshaft forward coupling assembly had failed. The outer coupling remained intact but the splines of the inner coupling had failed.
Accident investigation:
 |
|
Sources:
https://www.atsb.gov.au/publications/investigation_reports/1995/aair/199502624/
https://www.atsb.gov.au/media/4933128/199502624.pdf
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 09-Apr-2018 18:26 | Pineapple | Added |
Corrections or additions? ... Edit this accident description
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