Probable cause
Failure of a seal in the hydraulic system resulting in a loss of hydraulic pressure while maneuvering at low altitude.
NTSB analysis
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.
Text from the NTSB. Open the NTSB docket for WPR09LA371 for the full record.
Event
- Date
- Jul 24, 2009
- Type
- Accident
- Place
- Chelan, Washington
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Sikorsky S-55
- N-number
- N1255T
- Category
- Helicopter
- Damage
- Substantial
- Operating rule
- Part 91 (general aviation)
- Purpose of flight
- Other work use
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.