Sikorsky S-55 accident near Chelan, Washington, July 24, 2009
On July 24, 2009 at about 9:45 pm local time, a Sikorsky S-55 (helicopter), registered N1255T, was substantially damaged in an accident during maneuvering (low-alt flying) near Chelan, Washington. It was an other work-use flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
Failure of a seal in the hydraulic system resulting in a loss of hydraulic pressure while maneuvering at low altitude.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 24, 2009 · about 9:45 pm local time
- Place
- Chelan, Washington · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Sikorsky S-55 · all S-55s on the register
- Registration
- N1255T · registry record · serial 55607
- Damage
- Substantial damage
- Flight
- Other work-use flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot was using rotor wash to dry cherries at low altitude when the helicopter lost hydraulic pressure. After clearing a stand of trees, the pilot made an emergency run-on landing into a vacant field. During the landing, one of the landing skids hit a large hole, and the main rotor severed the tail boom. Post accident examination revealed that an internal seal had leaked resulting in the loss of pressure in the hydraulic system.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Sys/Comp malf/fail (non-power) during maneuvering (low-alt flying) defining event
- Off-field or emergency landing during landing (landing roll)
- Collision with terrain or object (not controlled flight into terrain) during landing (landing roll)
The NTSB's findings
- cause Aircraft › Aircraft systems › Hydraulic power system › Hydraulic, main system › Malfunction
- Environmental issues › Physical environment › Terrain › Rough terrain › Contributed to outcome
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instructor: airplane multi-engine; instructor: instrument airplane; instrument: airplane; rotorcraft: helicopter
- Flight time: 35,000 hours in all; 200 in this make and model
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 7,530 hours
- Landing gear: fixed
- Engine: Aireasearch TSE331 (turboshaft); 0 hours total
The flight
- Departed from: Chelan WA at 7:45 pm
- Destination: Chelan WA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 300° at 5 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 9,000 ft
- Temperature: 79°F (26°C), dew point 50°F (10°C)
- Altimeter: 29.98 inHg
- Observation at 9:55 pm from KEAT
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number WPR09LA371.