Probable cause
The failure of the engine's No.3 intake valve resulting is a loss of engine power and a rollover following the autorotation to soft ground.
NTSB analysis
The student pilot turned the helicopter onto the crosswind leg of the traffic pattern during a training flight when the engine suddenly began to run rough and lost partial power. The flight instructor took the controls and executed an autorotation into a clearing. The skids of the helicopter sank into the soft mud, the rotor blades contacted the ground, and the helicopter rolled onto its side.
Examination of the engine revealed that a portion of the No. 3 cylinder intake valve had broken off and migrated into the No. 1 cylinder, where it lodged between the No. 1 cylinder's intake valve and seat, holding that valve in the open position and resulting in the partial loss of engine power.
Text from the NTSB. Open the NTSB docket for CEN20LA051 for the full record.
Event
- Date
- Dec 31, 2019
- Type
- Accident
- Place
- Danbury, Texas
- Nearest airport
- Salaika Aviation (07TA)
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Enstrom F28
- N-number
- N57SJ
- Category
- Helicopter
- Year built
- 1975
- 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.