# NTSB CEN19LA162: Robinson R44, N4504L, Last Chance, CO, June 8, 2019 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: June 8, 2019, 11:59 local (17:59 UTC) - Place: Last Chance, CO - Coordinates: 39.787498, -103.770553 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.7875&lon=-103.7706&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of lift](https://openairdocs.org/ntsb-events/500) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 99593 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN19LA162 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99593/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99593 - Page: https://openairdocs.org/ntsb/CEN19LA162 ## Probable cause The pilot's failure to maintain adequate main rotor rpm while descending with a tailwind during an aerial application maneuver, which resulted in an uncontrolled descent into terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Robinson Helicopter R44 II, 99 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7640122), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: descent rate](https://openairdocs.org/ntsb-findings/01062037): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R44 II, 7 cases](https://openairdocs.org/ntsb-findings/01062037/cases.md?model=7640122), [All aircraft, 242 cases](https://openairdocs.org/ntsb-findings/01062037/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Decision related to condition (probable cause); cases with it: [Robinson Helicopter R44 II, 13 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=7640122), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause); cases with it: [Robinson Helicopter R44 II, 13 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=7640122), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Response/compensation (probable cause); cases with it: [Robinson Helicopter R44 II, 13 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=7640122), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Awareness of condition (probable cause); cases with it: [Robinson Helicopter R44 II, 13 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=7640122), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Contributed to outcome (probable cause); cases with it: [Robinson Helicopter R44 II, 13 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=7640122), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/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 lift](https://openairdocs.org/ntsb-events/500) (defining event); cases with it: [Robinson Helicopter R44 II, 4 cases](https://openairdocs.org/ntsb-events/500/sequence.md?model=7640122), [All aircraft, 252 cases](https://openairdocs.org/ntsb-events/500/sequence.md) ## Analysis The helicopter pilot was performing an agricultural application flight. He approached the field from the east and completed a survey of the area that he intended to spray about 100 ft above ground level (agl). After maneuvering around the area, he decided to complete the east-west spray passes on the south side of the field and work north in order to have a crosswind during the passes. While flying east about 100 ft and 50 knots, he initiated a right turn, and the helicopter descended. As the helicopter continued the right turn and passed through a southwest heading, the gusting wind from the northeast resulted in a tailwind condition. During the descent with full throttle applied, the main rotor rpm began to decrease. The pilot lowered the collective and pitched forward to gain airspeed, but the main rotor rpm continued to decrease. About 50 ft agl, he started to jettison the spray load and was unable to increase the rotor rpm; the helicopter subsequently impacted the ground and came to rest on its side resulting in substantial damage to the tailboom. A postaccident examination of the helicopter did not reveal any anomalies that would have precluded normal operation. The circumstances of the accident are consistent with a loss of main rotor rpm while descending with a tailwind, which resulted in an uncontrolled descent into terrain. ## Factual narrative On June 8, 2019, at 1159 mountain daylight time, a Robinson R44 helicopter, N4504L, was substantially damaged when it was involved in an accident when it impacted terrain during a low altitude aerial application operation near Last Chance, Colorado. The commercial pilot sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. After the accident, the pilot stated that the helicopter was loaded with about 50 gallons of herbicide and about 10 gallons of fuel and that he intended to spray a 20-acre pasture. He estimated that the wind was from the north-northwest about 10 to 12 knots when he departed; the wind was shifting toward the north. He reported that after takeoff the helicopter exhibited no performance issues. He reported that he completed a survey of the area that he intended to spray about 100 ft above ground level (agl), then noticed that the helicopter was "lacking performance" so he completed one spray pass into the wind and then jettisoned about 5 gallons of herbicide to increase the helicopter's performance characteristics. After circling around the area, he decided to complete the east-west spray passes on the south side of the field and work north, in order to have a crosswind during the passes. He added that he completed the circle and flew south at about 100 ft and 50 knots with a tailwind, then made a gradual 90° right turn to start the decent into the field. He stated that during the descent the rotor rpm started to decrease. He stated that he already had the throttle full open, so he lowered the collective and pitched forward to gain airspeed; the rotor rpm continued to decrease. About 50 ft agl he started to jettison the entire load and was unable to increase the rotor rpm; the helicopter impacted the ground with a forward speed of about 60 knots. The owner spoke with the pilot after the accident and he stated that the pilot was setting up to spray a thistle patch. The pilot banked the helicopter around to the right to start the spray first pass when the rotor rpm began to decay. The pilot tried to recover the rotor rpm but was unable to at such a low altitude. He added that the engine was already at full throttle, so the pilot jettisoned the load. The pilot thought he had enough forward speed to begin a climb but was unable. The helicopter came to rest on its right side in an open field. The tailboom and spray equipment separated during the accident sequence. The company's recorded GPS data revealed that the helicopter initially approached the field from the south and made one pass over the field about 15 ft agl. The helicopter completed a figure-eight maneuver on the north side of the field then looped around on the west side of the field and approached to the east. While heading east, the helicopter made another pass over the field about 5 ft agl. The helicopter made one final right turn back toward the south side of the field and headed west; theapex of the turn was about 100 ft agl. The helicopter descended and the flight track ended on the south corner of the field. The responding Federal Aviation Administration (FAA) inspector confirmed from the recorded weather report that the wind was from the northeast at the time of the accident. The inspector completed an examination of the wreckage which revealed no anomalies that would have precluded normal operation. FAA Helicopter Flying Handbook – Helicopter Performance "Headwinds are the most desirable as they contribute to the greatest increase in performance. Strong crosswinds and tailwinds may require the use of more tail rotor thrust to maintain directional control. This increased tail rotor thrust absorbs power from the engine, which means there is less power available to the main rotor for the production of lift." ## Aircraft - Registration: [N4504L](https://openairdocs.org/deregistered/N4504L-2020-10-17), registration cancelled 2020-10-17, S/N 13084, built 2011 (OpenAirDocs) - Reported make and model: Robinson 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: 13084 - Year built: 2011 - Airframe hours: 1809.8 - Engines: Lycoming IO-540-AE1A5 245 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Scott, Kyle - Registered owner: CO Fire Aviation - Airworthiness certificate: Standard, Normal; Special, Restricted (Special) - Last inspection: 100 hour, January 24, 2019 - Departed: Last Chance, CO - Destination: Last Chance, CO ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 39; injuries: minor; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane, helicopter; medical: class 2, without waivers/limitations; last flight review June 3, 2017; seat: right; restraint: 3-point; flight hours: 1,539 total, 1,261 in this make and model, 1,416 as pilot in command, 50 in the last 90 days, 42 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 21° at 17 knots, gusting 21 - Lowest ceiling: none - Temperature: 73 °F, dew point 50 °F - Altimeter: 29.94 inHg - Observed at: 3 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 20190608006239A](https://openairdocs.org/incident/20190608006239A), Jun 8, 2019: Robinson Helicopter Company R44 II, Last Chance, CO, Destroyed. While conducting part 137 spraying operations near Last Chance, CO, N4504L experienced a loss of main rotor RPM and impacted terrain in the field being sprayed… ## Docket (8 files) The files NTSB released with the investigation on November 19, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99593. 7.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 4.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8282643&FileExtension=pdf&FileName=6120%20-%20pilot%20walters_Redacted-Rel.pdf - Correspondence - owner (item 2, PDF, 1 page, 49 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8282929&FileExtension=pdf&FileName=ROC%20-%20Kyle%20Scott%20(owner)-Rel.pdf - Correspondence - pilot (item 3, PDF, 1 page, 129 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8282652&FileExtension=pdf&FileName=ROC%20-%20Jason%20Walters%20(pilot)-Rel.pdf - Correspondence - FAA inspector (item 4, PDF, 1 page, 53 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8285879&FileExtension=pdf&FileName=ROC%20-%20Bret%20Proud%20(FAA)-Rel.pdf - Photos (item 5, PDF, 7 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8290989&FileExtension=pdf&FileName=Docket%20Photos-Rel.pdf - Flight track tabular data (item 6, CSV, 836 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8282056&FileExtension=csv&FileName=Flight%20track%20data%20csv%20final-Rel.csv - Release of aircraft wreckage, NTSB form 6120.15 (item 7, PDF, 1 page, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11369269&FileExtension=pdf&FileName=-%20Wreckage%20Release%20Form%20-%20N4504L%20(signed)_Redacted-Rel.pdf - Weather reports and records (item 8, PDF, 1 page, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8286575&FileExtension=pdf&FileName=Weather%20data%20(raceway)-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.