ASN Wikibase Occurrence # 169232
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| Date: | Friday 29 August 2003 |
| Time: | 17:15 LT |
| Type: |  Aérospatiale AS 332L Super Puma |
| Owner/operator: | Bristow Helicopters Australia (BHA) |
| Registration: | VH-BHY |
| MSN: | 2129 |
| Fatalities: | Fatalities: 0 / Occupants: 8 |
| Aircraft damage: | Minor |
| Location: | Karratha, WA -
 Australia
|
| Phase: | En route |
| Nature: | Offshore |
| Departure airport: | Karratha, WA |
| North Rankin A offshore platform | |
| Confidence Rating: |  Information verified through data from accident investigation authorities |
The crew reported feeling a sudden airframe jolt, followed by a pitch up, roll, and a left yawing motion. Finding they had lost tail rotor control, the crew stabilised the aircraft using pitch and roll control inputs, before declaring a MAYDAY to air traffic services.
The crew elected to return to Karratha where a run-on landing was safely conducted.
The investigation found that the loss of tail rotor control reported by the flight crew of VH-BHY occurred as a result of the disconnection of the tail rotor pitch change servo from the control rod. That disconnection was a direct result of a breakdown in the anti-friction properties of the tail rotor pitch change shaft bearing, allowing the rotational torque along the pitch change shaft to overcome the assembly torque and locking assembly of the servo end shaft nut. The rotating shaft subsequently unscrewed the nut, allowing it to drop into the tail structure from where it was recovered.
The tail rotor pitch change shaft bearing failure occurred as a result of the contamination and dilution of the grease lubricant, leading to the internal mechanical breakdown of the bearing cage and the partial seizure of the assembly. Testing showed that the bearing grease was contaminated by hydraulic fluid, which likely released from a leaking tail rotor servo-actuator unit identified and replaced 22 days before the incident. The bearing was inspected at the time of the leak discovery and was found to be satisfactory for further service. At that time, there was no requirement to change the bearing in the event of the leakage of hydraulic fluid into the bearing space.
Sources:
http://www.atsb.gov.au/publications/investigation_reports/2003/aair/aair200303804.aspx
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Aug-2014 07:01 | Aerossurance | Added |
| 10-Apr-2015 20:23 | TB | Updated [Aircraft type] |
Corrections or additions? ... Edit this accident description
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