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).
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 November 2, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 24, 2009 · about 9:45 pm local time · cases in 2009
- 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 other cases naming the heating, ice protection and utility systems
- 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
2 documents, released by the NTSB on September 15, 2010. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Witness Statement - Record of Conversation Pilot | PDF, 1 page | View Download |
| 2 | Record of Conversation FAA | PDF, 1 page | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Connections how this case links to the rest of the register
- N1255T on the register today · the tail number may have moved to another aircraft since
- Sikorsky S-55 15 registered today · the model family and its accident history
- Sikorsky 825 aircraft on the register
- Engine: Aireasearch TSE331 · as the NTSB recorded it
- Accidents and incidents in Washington 2,713 since 1982 · 362 in the last ten years
- Washington 10,662 aircraft registered
The whole map of how records connect · these connections as data: /graph/accident/WPR09LA371.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.