Probable cause
A partial loss of engine power for reasons that could not be determined based on available information.
NTSB analysis
The pilot reported a decrease in engine and rotor rpm during cruise flight. The pilot reported that he heard sounds from the engine “like detonations,” and he placed the helicopter into autorotation and landed on a road. The helicopter rotor blades struck a pole and the helicopter rolled onto its right side. Downloaded data from the engine monitoring unit confirmed the decrease in engine and rotor rpm.
Functional testing of the engine and electronic governor control revealed no anomalies. Bench testing of the engine rpm sensor and the electronic governor control unit also revealed no anomalies. During functional testing, it was confirmed that the manual throttle control could be used to override the governor control.
Based on the available information, the reason for the decrease in engine rpm reported by the pilot could not be determined.
Text from the NTSB. Open the NTSB docket for CEN21LA369 for the full record.
Event
- Date
- Aug 11, 2021
- Type
- Accident
- Place
- Wheeling, Illinois
- Nearest airport
- Chicago Exec (PWK)
- Highest injury
- Minor
- Minor injuries
- 1
- Weather
- Visual (VMC)
- Light
- Day
Robinson Helicopter Company R44 II
- N-number
- N4043B
- Category
- Helicopter
- Year built
- 2021
- 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.