ASN Wikibase Occurrence # 153629
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| Date: | Monday 12 November 2001 |
| Time: | 14:20 |
| Type: |  Bell 407 |
| Owner/operator: | Helicopter Express Inc. |
| Registration: | N11HX |
| MSN: | 53471 |
| Year of manufacture: | 2001 |
| Total airframe hrs: | 321 hours |
| Engine model: | Allison 250-C47B |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | near Whitley City, KY -
 United States of America
|
| Phase: | Unknown |
| Nature: | Fire fighting |
| Departure airport: | Whitley City, KY |
| Investigating agency: | NTSB |
| Confidence Rating: |  Information verified through data from accident investigation authorities |
The pilot was conducting a fire suppression flight. While indicating approximately 100 knots of airspeed, with an empty water bucket that was occasionally unstable during the flight, the pilot heard a "bang." The helicopter yawed to the right, and the tail rotor quit spinning. The pilot jettisoned the bucket, and because there was no place to land, he continued to the dip-point. At the dip-point, the pilot selected an open area. The area was sloped, but the pilot was uncertain of the airworthiness of the helicopter and did not want to look for another area. He entered a "needles joined autorotation." As the helicopter slowed, it started to spin to the right. The spin stopped, the helicopter impacted the ground, and then rolled onto its right side with little or no power applied to the main rotor. Examination of the wreckage revealed that the bucket had entered the arc of the tail rotor, and that the tail-rotor driveshaft was severed consistent with overload. The operating manual for the bucket stated that the bucket had been proven stable up to an airspeed of approximately 96 knots, and that a bucket with a overall length greater than the distance from the cargo hook to the front arc of the tail rotor could result in a tail rotor strike. The emergency procedure for a complete loss of tail rotor thrust in-flight was reduce throttle to idle, and immediately enter autorotation. If a suitable landing site was not available, the vertical fin may permit controlled flight to a suitable area.
Probable Cause: The pilots decision to operate the helicopter at an airspeed in excess of the maximum demonstrated stable airspeed for the water bucket. A factor in the accident was the pilot did not follow the published emergency procedure.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20011202X02329&key=1
Air International March 2002, p143
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 01-Mar-2013 11:38 | TB | Added |
| 21-Dec-2016 19:28 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 10-Dec-2017 13:17 | ASN Update Bot | Updated [Operator, Nature, Departure airport, Source, Narrative] |
| 11-Apr-2018 06:59 | TB | Updated [Nature, Source, Damage] |
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