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| Date: | Thursday 10 October 2024 |
| Time: | 15:22 |
| Type: |  Bell 412EP |
| Owner/operator: | Shin Nihon Helicopter - SNK |
| Registration: | JA6412 |
| MSN: | 36561 |
| Year of manufacture: | 2010 |
| Engine model: | P&W Canada PT6T |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Other fatalities: | 0 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Yasuduka ward, Joetsu city, Niigata prefecture -
 Japan
|
| Phase: | En route |
| Nature: | Cargo |
| Departure airport: | Yasuduka Temporary Airfield |
| Cupidvalley, Joetsu city, Niigata prefecture | |
| Investigating agency: | JTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
A Bell 412EP of Shin Nihon Helicopter carrying 820 kg of freshly mixed concrete to a skiing facility "Cupidvalley" of Jotsu city, Niigata. Just before the landing, the onboard crew noticed the whole of the concrete had been lost in the carrying backet while flying 500 feet over mountaineous terrain. No ground damage were reported.
PROBABLE CAUSES
The JTSB concludes that the probable cause of this serious incident was that the bottom plate of the bucket most likely opened unintentionally while the helicopter was flying with a bucket of ready-mixed concrete slung over, causing the ready-mixed concrete inside the bucket to fall.
Regarding the unintentional opening of the bottom plate of the bucket, it is more likely that as the service time of the bucket increased, the fulcrum of the link became shallower, preventing the lock from working properly, in addition, as the load on the bottom plate increased due to centrifugal force as the helicopter turned right, the bottom plate was no longer able to withstand the load.
Accident investigation:
 |
|
Sources:
https://nordot.app/1217109478357303435
https://newsdig.tbs.co.jp/articles/bsn/1485208?display=1
https://snkk-net.com/news/%e3%80%90%e3%81%8a%e8%a9%ab%e3%81%b3%e3%80%91%e3%83%98%e3%83%aa%e3%82%b3%e3%83%97%e3%82%bf%e3%83%bc%e3%81%8b%e3%82%89%e3%81%ae%e9%81%8b%e6%90%ac%e7%89%a9%e8%90%bd%e4%b8%8b%e3%81%ab%e3%81%a4%e3%81%84/
https://jtsb.mlit.go.jp/jtsb/aircraft/detail2.php?id=2406
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 10-Oct-2024 15:42 | isamuel | Added |
| 11-Oct-2024 16:18 | isamuel | Updated [Destination airport, Source, Narrative, ] |
| 15-Oct-2024 11:12 | isamuel | Updated [Departure airport, Source, Narrative, ] |
| 16-Oct-2025 06:22 | ASN | Updated [Narrative, Accident report, ] |
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