ASN Wikibase Occurrence # 44747
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| Date: | Wednesday 11 August 2004 |
| Time: | 10:25 |
| Type: |  Bell 205A-1 |
| Owner/operator: | U.S. Forest Service |
| Registration: | N205XP |
| MSN: | 30017 |
| Year of manufacture: | 1968 |
| Total airframe hrs: | 28600 hours |
| Engine model: | Lycoming T-53-L-17A |
| Fatalities: | Fatalities: 1 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Leavenworth, WA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Fire fighting |
| Departure airport: | Leavenworth, WA |
| Leavenworth, WA | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The helicopter was operating under contract to the United States Forest Service (USFS). The purpose of the external load flight was to deliver equipment to a crew of smoke jumpers fighting a fire in heavily wooded, mountainous terrain. The jumpers estimated the trees in the area were a maximum of 120 feet tall, and therefore, they requested a 150 foot long line be used for the equipment drop. The helicopter was dispatched with a tandem load on a 160 foot long line. The smoke jumpers placed a marker on a sand bar in a stream bed. There was a tall dead tree (snag) located on a cut bank overlooking the sand bar. As the helicopter approached the area, one of the smoke jumpers communicated by radio with the pilot that if he did not like the marked site, he could choose his own spot. The pilot replied that he would give the marked spot a try. The radio operator did not mention the snag to the pilot. The pilot successfully placed both loads on the marker. Another smoke jumper disconnected both loads and then reconnected one of the loads meant to be dropped at another location. As the helicopter began its departure, the pilot who was sitting in the left seat, slowly turned the helicopter's nose to the left and its tail to the right. This maneuver allowed the helicopter's tail rotor to contact the snag. The helicopter began to spin and then fell to the ground. Investigation revealed that the snag was located 36 feet from the marker and was about 173 feet tall. The rotor diameter of the helicopter was 48 feet. Following the accident, the USFS issued an Aviation Safety Alert on the subject of "Clearance From Obstacles During External Load Operations." One of the recommendations in the alert stated the following: "In areas of sloping terrain or with obstacles rising to one or more sides of the cargo pickup/delivery area, or dip site, pilot should maintain aircraft clearance from all obstacles in accordance with the landing area safety circle requirements for the type aircraft. The safety circle is generally recognized as 1 1/2 times the rotor diameter."
Probable Cause: The pilot's failure to maintain clearance from the snag while hovering out of ground effect during an external load operation. Factors were the smoke jumper's misjudgment of the tree heights in the area, which resulted in the use of too short a long line, and their failure to communicate with the pilot about the tall snag.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20040816X01225&key=1
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 28-Oct-2008 00:45 | ASN archive | Added |
| 02-Sep-2014 10:25 | Aerossurance | Updated [Nature, Source, Narrative] |
| 21-Dec-2016 19:24 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 07-Dec-2017 18:20 | ASN Update Bot | Updated [Operator, Nature, Source, Narrative] |
| 01-May-2022 08:59 | Ron Averes | Updated [Operator] |
| 12-Nov-2022 02:51 | Ron Averes | Updated [Operator] |
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