# NTSB CEN21LA155: Robinson Helicopter R44, N7184N, Dunn, TX, February 26, 2021

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: February 26, 2021, 15:40 local (21:40 UTC)
- Place: Dunn, TX
- Coordinates: 32.553436, -100.88875 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=32.5534&lon=-100.8888&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Defining event: [Maneuvering-low-alt flying: Low altitude operation/event](https://openairdocs.org/ntsb-events/220)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Central Region
- Parties: Federal Aviation Adminsitration, Lycoming Engines, Robinson Helicopter Company
- NTSB case key (mKey): 102747
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA155
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102747/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102747
- Page: https://openairdocs.org/ntsb/CEN21LA155

## Probable cause

The loss of rotor RPM for reasons that could not be determined based on available evidence.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R44, 15 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=7640120), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md)
- [Environmental issues](https://openairdocs.org/ntsb-findings/03010000): Environmental issues › Operating environment · Contributed to outcome (probable cause); cases with it: [Robinson Helicopter R44, 1 case](https://openairdocs.org/ntsb-findings/03010000/cases.md?model=7640120), [All aircraft, 14 cases](https://openairdocs.org/ntsb-findings/03010000/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Maneuvering-low-alt flying: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Robinson Helicopter R44, 43 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=7640120), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md)
- [Maneuvering-low-alt flying: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) (defining event); cases with it: [Robinson Helicopter R44, 26 cases](https://openairdocs.org/ntsb-events/220/sequence.md?model=7640120), [All aircraft, 780 cases](https://openairdocs.org/ntsb-events/220/sequence.md)

## Analysis

The pilot and two passengers were completing an aerial gunning flight. The helicopter was flying at 80 ft above ground level (agl), when the pilot heard the “rotors droop” and the “engine bog down.” He stated that he applied right pedal and increased the throttle input, but the engine did not respond. The helicopter descended into the trees and impacted the ground. The main rotor blades and fuselage sustained substantial damage. The investigation was unable to determine the airspeed of the helicopter and the reason for the loss of rotor RPM based on the available evidence. A postaccident examination and engine functional test run revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

## Factual narrative

On February 26, 2021, at about 1540 central standard time, a Robinson R44 helicopter, N7184N, was substantially damaged when it was involved in an accident near Dunn, Texas. The pilot and two passengers were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 aerial gunning flight. The pilot reported that he had just refueled the helicopter and departed again with the fuel tanks about half full. While flying at 80 ft above ground level (agl), he heard the “rotors droop” and “engine bog down.” He applied right pedal and increased the throttle input, but the engine did not respond. The helicopter descended into the trees. The helicopter impacted the ground and sustained substantial to the fuselage. The investigation was unable to determine the airspeed of the helicopter based on the available evidence. A postaccident examination and engine functional test run revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

## Aircraft

- Registration: [N7184N](https://openairdocs.org/aircraft/N7184N), registered now, S/N 0116 (OpenAirDocs)
- Reported make and model: ROBINSON HELICOPTER R44
- Registry model: [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44) (registry code 7640120) (OpenAirDocs)
- Category: Helicopter
- Serial number: 0116
- Year built: 1999
- Airframe hours: 1749
- Engines: Lycoming O-540-F1B5 540 horsepower reciprocating
- Damage: Substantial damage
- Flight: Other work use, Part 91
- Operator: Top Gun Precision Ag LLC, doing business as Ace High Helos
- Registered owner: Top Gun Precision Ag LLC
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, February 16, 2021, 10 hours before
- Equipment: ADS-B

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 32; injuries: none; commercial; medical: class 2, without waivers/limitations; last flight review February 28, 2020; seat: right; restraint: lap only; flight hours: 1,398 total, 378 in this make and model, 1,318 as pilot in command, 70 in the last 90 days, 70 in the last 30 days, 8 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 240° at 11 knots, gusting 14
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 68 °F, dew point 28 °F
- Altimeter: 29.83 inHg
- Observed at: KSNK, 9 nm away
- METAR: KSNK 262155Z AUTO 24011G14KT 10SM CLR 20/M02 A2983 RMK AO2 T01991023

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20210226003599A](https://openairdocs.org/incident/20210226003599A), Feb 26, 2021: Robinson Helicopter R44, Dunn, TX, Destroyed. On February 26, 2021 at approximately 1600, a Robinson R44 helicopter bearing registration number N7184N, [privacy data omitted], experienced a loss/reduction…

## Docket (8 files)

The files NTSB released with the investigation on September 23, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102747. 324 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 5.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12053904&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf
- Correspondence - owner (item 2, PDF, 2 pages, 129 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12874297&FileExtension=pdf&FileName=ROC%20-%20Brandon%20Nau%20(owner)-Rel.pdf
- Maintenance logbook entries - annual inspection (item 3, PDF, 2 pages, 47.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12875348&FileExtension=pdf&FileName=Last%20annual%20inspection_Redacted-Rel.pdf
- Engine test run summary (item 4, PDF, 3 pages, 227 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12876091&FileExtension=pdf&FileName=Engine%20run%20and%20exam%20summary-Rel.pdf
- Engine functional test run video (item 5, MP4, 265 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12875392&FileExtension=mp4&FileName=Engine%20run%20video-Rel.mp4
- Photos (item 6, PDF, 7 pages, 7 photos, 4.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12875822&FileExtension=pdf&FileName=Photos-Rel.pdf
- Statement of party representatives to NTSB investigation (item 7, PDF, 2 pages, 945 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12875454&FileExtension=pdf&FileName=Party%20forms%20signed_Redacted-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 8, PDF, 1 page, 134 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12876081&FileExtension=pdf&FileName=Wreckage%20Release%20Form%20-%20N7184N%20(signed)_Redacted-Rel.pdf

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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