Probable cause
The pilot's improper use of the throttle grip, which resulted in the deactivation of the rpm governor and a loss of rotor rpm.
NTSB analysis
During a solo instructional flight, the pilot reported that while on the downwind leg of the traffic pattern, just before turning to the base leg, the helicopter sustained a loss of rotor rpm. The pilot reported that he entered an autorotation and that the throttle was unresponsive. After landing in a marsh area, the helicopter rolled over.
A postaccident examination of the helicopter and a successful engine run revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The pilot's flight instructor related that the pilot had a documented history of inadvertently gripping the throttle on the collective which, while manipulating the collective, would result in overriding the governor and a low rotor condition.
Text from the NTSB. Open the NTSB docket for WPR12LA140 for the full record.
Event
- Date
- Mar 15, 2012
- Type
- Accident
- Place
- Palo Alto, California
- Nearest airport
- Palo Alto Airport (PAO)
- Highest injury
- Minor
- Minor injuries
- 1
- Weather
- Visual (VMC)
- Light
- Day
Robinson Helicopter R22 BETA
- N-number
- N290SH
- Category
- Helicopter
- Damage
- Substantial
- Operating rule
- Part 91 (general aviation)
- Purpose of flight
- Instructional
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.