# NTSB CEN21LA173: Robinson Helicopter R44 II, N178DF, Dustin, OK, March 26, 2021 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Final report - Date: March 26, 2021, 15:15 local (20:15 UTC) - Place: Dustin, OK - Coordinates: 35.2707, -96.0308 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.2707&lon=-96.0308&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Serious injuries - Injuries: 2 serious, 2 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Federal Aviation Administration; Will Rogers Flight Standards District Office - NTSB case key (mKey): 102855 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA173 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102855/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102855 - Page: https://openairdocs.org/ntsb/CEN21LA173 ## 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. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Robinson Helicopter R44 II, 12 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=7640122), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R44 II, 6 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=7640122), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Object/animal/substance: tree(s)](https://openairdocs.org/ntsb-findings/03022020): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [Robinson Helicopter R44 II, 9 cases](https://openairdocs.org/ntsb-findings/03022020/cases.md?model=7640122), [All aircraft, 933 cases](https://openairdocs.org/ntsb-findings/03022020/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) (defining event); cases with it: [Robinson Helicopter R44 II, 74 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=7640122), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Uncontrolled descent: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Robinson Helicopter R44 II, 24 cases](https://openairdocs.org/ntsb-events/060/sequence.md?model=7640122), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Landing: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Robinson Helicopter R44 II, 16 cases](https://openairdocs.org/ntsb-events/490/sequence.md?model=7640122), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Analysis 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. ## Factual narrative On March 26, 2021, about 1515 central daylight time, a Robinson Helicopter Company R44 II, N178DF, was substantially damaged when it was involved in an accident near Dustin, Oklahoma. The private pilot and one passenger received serious injuries, and two passengers received minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight. The pilot 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 the helicopter immediately, during which the helicopter impacted a tree then terrain, resulting in substantial damage that included damage to the main rotor, fuselage, and tailboom. The pilot reported that there were no mechanical malfunctions or failures with the helicopter, and recommended operating “at a lower gross weight.” Postacccident examination of the helicopter revealed no anomalies that would have precluded normal operation. ## Aircraft - Registration: [N178DF](https://openairdocs.org/deregistered/N178DF-2023-06-28), registration cancelled 2023-06-28, S/N 11969, built 2007 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER COMPANY R44 II - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540-AE1A5](https://openairdocs.org/engine/lycoming-io-540-ae1a5) (registry code 41899, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 11969 - Year built: 2007 - Airframe hours: 2347 - Engines: Lycoming IO-540-AE1A5 290 hp reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Operator: Brush Popper Aviation LLC - Registered owner: Brush Popper Aviation LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 18, 2021 - Departed: F10, Henryetta, OK - Equipment: Electronic flight bag or handheld device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; injuries: serious; private; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review June 3, 2020; seat: right; restraint: 4-point; flight hours: 3,687 total, 1,447 in this make and model, 3,552 as pilot in command, 124 in the last 90 days, 82 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 14 knots, gusting 21 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 45 °F - Altimeter: 29.89 inHg - Observed at: OKM, 90 nm away ## 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 20210326005769A](https://openairdocs.org/incident/20210326005769A), Mar 26, 2021: Robinson Helicopter Company R44 II, Dustin, OK, Substantial damage. The pilot was hired [privacy data omitted] for hog depredation. On March 26, 2021 the pilot picked up three passengers from the property, flew to henrietta… ## Docket (5 files) The files NTSB released with the investigation on July 29, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102855. 159 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 796 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12210194&FileExtension=pdf&FileName=NTSB%20Form_Redacted-Rel.pdf - FAA inspector statement (item 2, PDF, 1 page, 156 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12210329&FileExtension=pdf&FileName=ASI%20Inspection%20report%20N178DE%20(002)-Rel.pdf - Photo log (item 3, PDF, 1 page, 523 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13598451&FileExtension=pdf&FileName=Photo%20Log-Rel.pdf - Airframe logs (item 4, PDF, 38 pages, 79.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12210233&FileExtension=pdf&FileName=Airframe%20Logbook%20Entries%20-%20N178DF_Redacted-Rel.pdf - Engine logs (item 5, PDF, 37 pages, 78.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12210393&FileExtension=pdf&FileName=Engine%20Logbook%20Entries%20-%20N178DF_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. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.