ASN Wikibase Occurrence # 342907
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| Date: | Thursday 15 August 2002 |
| Time: | |
| Type: |  Aerospatiale SA 315B Lama |
| Owner/operator: | Western Aerial Applications Ltd. |
| Registration: | C-GGHG |
| MSN: | 2524 |
| Year of manufacture: | 1978 |
| Engine model: | Turbomeca ARTOUSTE IIIB |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | 19 NM SE of McBride, BC -
 Canada
|
| Phase: | En route |
| Nature: | Ferry/positioning |
| Departure airport: | Kamloops, BC |
| McBride, BC | |
| Investigating agency: | TSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The Aerospatiale SA 315B Lama helicopter was on a visual flight rules ferry flight from Mission, British Columbia, to McBride, via Kamloops, with the pilot and two passengers on board. At about 1830 Pacific daylight time, 45 minutes after take-off, the passenger sitting in the left rear seat reported hearing a bang behind him. The pilot did not observe anything unusual and felt nothing abnormal in the controls. During the refuelling stop in Kamloops, the pilot inspected the helicopter and found nothing remarkable. Near Blue River, about 45 minutes after departing for McBride, the passenger once more heard the bang from the left side; again, the pilot did not experience anything unusual and continued the flight.
Between Valemount and McBride, at about 6000 feet above sea level, the helicopter yawed briskly to the right, followed by a loud bang and a 'woof' sound. The pilot lowered the collective lever to enter autorotation, confirmed that the engine had stopped, turned the helicopter to a suitable landing site, and carried out a run-on landing with low rotor rpm. The helicopter landed hard, the rear passenger seat broke, and the passengers suffered minor injuries. The helicopter remained upright, and no fire occurred. Visual meteorological conditions existed at the time of the accident, and the emergency locator transmitter activated at impact.
Findings as to Causes and Contributing Factors
1. The forward coupling sleeve and its stub shaft in the engine drivetrain failed. As a result, the reduction gearbox driving the rotor became disconnected from the engine, forcing the pilot to conduct an autorotation.
2. The splitting of the forward coupling assembly is attributed to premature wear.
3. The premature wear was caused by a wobble of the shaft at the forward coupling sleeve, due to improper axial placement of the stub shaft into the coupling sleeve.
4. The below-specification hardness, resulting from improper heat treatment at manufacture, contributed to the premature wear.
5. The serrated adjusting washer failed and interfered with the lubrication of the drive coupling splines, thereby remarkably accelerating wear.
6. An anti-seize compound applied to the fuel injection tube outer support bushings during overhaul became displaced and combined with metallic debris to clog the coupling sleeve lubrication grooves. This contamination altered lubrication to the splined drive and contributed to accelerated wear.
7. The engine flamed out when the fuel supply through the fuel injection tube was disrupted.
8. The distortion of the fuel tube was caused by the amplitude of the vibration and the rotational flexion of the shaft, due to the fast-growing, premature wear of the splined drive.
9. During the autorotation descent, the rotor rpm was allowed to decrease, resulting in a high rate of descent and a hard landing, the rear seat breaking, and the two passengers sustaining minor injuries.
10. The sampling process and results of the spectrometric oil analysis were likely compromised. Consequently, they did not provide the operator with adequate warning of the deteriorating condition of the engine axial compressor forward coupling sleeve assembly.
Accident investigation:
 |
|
Sources:
CADORS 2002P0896
History of this aircraft
Other occurrences involving this aircraft
| 24 July 2000 | C-GGHG | Dwayne Air | 0 | S of Blairmore, AB | |
sub |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 25-Oct-2023 09:43 | harro | Updated |
Corrections or additions? ... Edit this accident description
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