CEN21LA173 · Robinson Helicopter Company R44 II
Brush Popper Aviation Robinson Helicopter Company R44 II · Accident: loss of control in flight while maneuvering
From Henryetta Municipal Airport (F10) to an unrecorded destination
Event
- NTSB case
- CEN21LA173
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- Event fatalities
- Unknown
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Robinson Helicopter Company R44 II
- Aircraft type
- Robinson R44
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N178DF
- Operator
- Brush Popper Aviation
- Onboard fatalities
- Unknown
- Route
- From Henryetta Municipal Airport (F10), Henryetta, OKTo not recorded
- Aircraft age
- About 14 years (built 2007)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering · low-altitude flying
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of control in flight
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft oper/perf/capability
- Environmental issues › Physical environment
- Personnel issues › Action/decision
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot of the helicopter stated that, while maneuvering “low and slow” with three passengers onboard, he noticed “insufficient power” and shortly thereafter, the low rotor rpm warning annunciated. He applied full throttle and attempted to regain rotor rpm but was unsuccessful. The pilot stated that he was forced to land immediately, during which the helicopter impacted a tree then terrain, resulting in substantial damage.
The pilot reported that there were no mechanical malfunctions or failures of the helicopter and recommended operating “at a lower gross weight.” Postacccident examination of the helicopter revealed no anomalies that would have precluded normal operation.
Probable cause
The pilot’s insufficient monitoring of the helicopter’s power while flying at low altitude and at low airspeed, which resulted in the loss of rotor rpm and impact with a tree and terrain.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN21LA173
- Event ID
- 20210401102855
- Case number
- CEN21LA173
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 75c93fe5822aafc399c5a0dd2ed6affcc17f2b5259e923dffeb2100e66e209e4; retrieved 2026-09-16T13:54:56.290Z.