ASN Wikibase Occurrence # 199145
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| Date: | Friday 18 August 2017 |
| Time: | 14:00 |
| Type: |  Robinson R44 II |
| Owner/operator: | MW Contracting (QLD) Pty Ltd |
| Registration: | VH-LGN |
| MSN: | 12052 |
| Year of manufacture: | 2008 |
| Fatalities: | Fatalities: 0 / Occupants: 4 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Channel Point, NT -
 Australia
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Darwin, NT |
| Channel Point, NT | |
| Investigating agency: | ATSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During approach to Channel Point, the helicopter began to vibrate in which the pilot conducted a precautionary landing. The helicopter landed hard and the tail boom was severed. None of the four occupants sustained any injuries.
ATSB final report:
Analysis
The onset of the mast oscillations, as described during this occurrence, was largely consistent with the flight conditions described in Safety Tip 19 in the Robinson Pilot’s Operating Handbook. While the pilot’s actions in this occurrence did not follow the recommendation listed in the Safety Tip, his actions were consistent with those from previous occurrences and also in accordance with Safety Tip 7, which recommends making a safe landing if unusual sound or vibration begins in flight.
Incorrect forward main rotor gearbox mounts were installed in the R44 helicopter during recent maintenance. The manufacturer had previously found that these softer forward gearbox mounts increased the likelihood of the onset of oscillations associated with mast rocking in Robinson R44 helicopters. The onset of the airframe oscillations experienced by the pilot in this occurrence were therefore consistent with the manufacturer’s findings.
The circumstances that resulted in the installation of the incorrect parts was not clear. However, this type of error highlights the importance of extra vigilance around visually and dimensionally‑similar parts.
Findings
These findings should not be read as apportioning blame or liability to any particular organisation or individual.
As the pilot commenced a descending right turn, the unexpected onset of severe fore and aft mast oscillations resulted in the pilot conducting an immediate landing that significantly damaged the helicopter.
The maintainer had inadvertently installed incorrect forward main rotor gearbox mounts, which had previously been found to contribute to the initiation of fore and aft mast oscillation.
Accident investigation:
 |
|
Sources:
http://www.atsb.gov.au/publications/investigation_reports/2017/aair/ao-2017-086/
http://www.airliners.net/photo/Untitled/Robinson-R-44-Raven-II/1394919
________________
Report: https://www.atsb.gov.au/media/5775360/ao-2017-086-final.pdf
Images:
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 22-Aug-2017 11:26 | Pineapple | Added |
| 22-Aug-2017 22:29 | Geno | Updated [Source] |
| 04-Dec-2018 00:57 | Iceman 29 | Updated [Source, Narrative, Photo] |
| 04-Dec-2018 01:00 | Iceman 29 | Updated [Photo] |
| 05-Dec-2018 10:43 | harro | Updated [Source, Accident report, ] |
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