Probable cause
The catastrophic failure and disintegration of the No. 6 engine piston, which resulted in a total loss of engine power.
NTSB analysis
The pilot reported that he was on a survey flight when the helicopter engine suddenly stopped; he elected to autorotate to a field. The area he landed in had high vegetation, which “grabbed” the helicopter skids and the helicopter impacted the ground hard. Examination of the helicopter revealed that the main rotor impacted the tailboom during the accident and the tail rotor had separated from the helicopter. Examination of the engine revealed the No. 6 piston had disintegrated catastrophically, which caused additional internal damage to the engine.
Text from the NTSB. Open the NTSB docket for CEN12LA650 for the full record.
Event
- Date
- Sep 19, 2012
- Type
- Accident
- Place
- Rio Vista, Texas
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Hiller UH-12B
- N-number
- N94735
- Category
- Helicopter
- Damage
- Substantial
- Operating rule
- Part 91 (general aviation)
- Purpose of flight
- Personal
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.