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| Date: | Wednesday 11 August 2021 |
| Time: | 06:40 LT |
| Type: |  Robinson R44 Raven II |
| Owner/operator: | Crown Point Helicopter LLC |
| Registration: | N4043B |
| MSN: | 14431 |
| Year of manufacture: | 2021 |
| Total airframe hrs: | 70 hours |
| Engine model: | Lycoming IO-540-AE1A5 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Other fatalities: | 0 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Prospect Heights, IL -
 United States of America
|
| Phase: | Initial climb |
| Nature: | Private |
| Departure airport: | Wheeling, IL |
| Morton Grove, IL | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: A partial loss of engine power for reasons that could not be determined based on available information.
Accident investigation:
 |
|
Sources:
NTSB CEN21LA369
Location
Media:
⚠️🇺🇸#ALERT: Helicopter crash reported on highway northwest of Chicago, Illinois#ProspectHeights l #IL
— Intel Point ALERTS (@IntelPointAlert) August 11, 2021
Two occupants are injured after a helicopter lost control and hit a busy roadway. Milwaukee Avenue will be closed in the coming hours as NTSB investigators work on scene. pic.twitter.com/lJVqhHdRL8
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 11-Aug-2021 14:48 | harro | Added |
| 11-Aug-2021 14:51 | harro | Updated [Location, Phase, Nature, Embed code, Narrative, ] |
| 11-Aug-2021 14:54 | harro | Updated [Phase, Departure airport, Source, Narrative, Category, ] |
| 11-Aug-2021 14:55 | harro | Updated [Time, ] |
| 11-Aug-2021 15:00 | harro | Updated [Time, Aircraft type, Registration, Cn, Operator, Source, ] |
| 11-Aug-2021 19:17 | Anon. | Updated [Total occupants, ] |
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