ASN Wikibase Occurrence # 151308
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| Date: | Saturday 15 December 2012 |
| Time: | 10:05 |
| Type: |  Eurocopter AS 350B3 Ecureuil |
| Owner/operator: | Prism Helicopters Inc. |
| Registration: | C-GYPH |
| MSN: | 3688 |
| Year of manufacture: | 2003 |
| Total airframe hrs: | 5559 hours |
| Engine model: | Turbomeca Arriel 2B |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | near Beluga, AK -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | External load operation |
| Departure airport: | Beluga, AK (PABG) |
| Beluga, AK (PABG) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The commercial helicopter pilot was transporting a 1,000-pound external sling load attached to a lightweight, synthetic 100-foot long-line when the load began to spin and swing underneath the helicopter. As the helicopter neared its destination, it suddenly yawed, and then started to spin uncontrollably, and the pilot immediately jettisoned the external load. As the helicopter continued to spin uncontrollably, it descended into an area of tall trees and then came to rest on its left side.
A postaccident inspection of the helicopter revealed that portions of the severed lightweight synthetic long-line had become entangled in the tail rotor gearbox output shaft and that the tail rotor gearbox assembly was torn free of the tail boom. Examination of the long-line revealed that its entire length was tightly wrapped, knotted, and kinked. The pilot reported that he had not received training in procedures to adequately stabilize external sling loads. Given the postaccident condition of the lightweight synthetic long-line, the pilot's statements, and the lack of a rotating swivel, it is likely that, once the external load began to spin, the long-line continued to tangle and tightly knot and ultimately reached its breaking point. Once the synthetic long-line separated, the portion still attached to the belly of the helicopter recoiled upward and eventually became entangled with the tail rotor gearbox output shaft. In addition, it is likely the pilot did not adequately monitor the condition of the external sling load while en route, and he failed to recognize the need to stabilize the load.
Probable Cause: The pilot's failure to stabilize the external load, which led to the synthetic long-line separating about midspan and the remaining line becoming entangled in the tail rotor gearbox output shaft and resulted in the separation of the tail rotor gearbox and subsequent loss of control. Contributing to the accident was the pilot's inadequate training.
Accident investigation:
 |
|
Sources:
NTSB
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 18-Dec-2012 21:55 | Geno | Added |
| 21-Dec-2012 10:55 | Alpine Flight | Updated [Aircraft type, Phase, Nature, Narrative] |
| 21-Dec-2016 19:28 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 28-Nov-2017 14:02 | ASN Update Bot | Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative] |
| 17-Apr-2022 16:31 | Aerossurance | Updated [Operator, Location] |
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