# NTSB GAA17CA151: Robinson Helicopter R44, N4534G, Holtville, CA, February 14, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: February 13, 2017, 21:30 local (Feb 14, 2017, 05:30 UTC) - Place: Holtville, CA - Coordinates: 32.811111, -115.380279 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=32.8111&lon=-115.3803&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 22, 2017 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 94756 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA17CA151 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94756/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94756 - Page: https://openairdocs.org/ntsb/GAA17CA151 ## Probable cause The pilot’s initiation of a left turn at a low altitude with low airspeed and a tailwind while operating near maximum gross weight, which resulted in the helicopter losing altitude, touching down on a dirt surface, and a subsequent dynamic rollover. ## 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, 40 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7640120), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Robinson Helicopter R44, 15 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=7640120), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Robinson Helicopter R44, 22 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=7640120), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/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, 3 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=7640120), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [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) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause); cases with it: [Robinson Helicopter R44, 6 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=7640120), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) - [Aircraft capability: maximum weight](https://openairdocs.org/ntsb-findings/01061035): Aircraft › Aircraft oper/perf/capability · Related operating info; cases with it: [Robinson Helicopter R44, 3 cases](https://openairdocs.org/ntsb-findings/01061035/cases.md?model=7640120), [All aircraft, 152 cases](https://openairdocs.org/ntsb-findings/01061035/cases.md) - [Runway/land/takeoff/taxi surface: soft surface](https://openairdocs.org/ntsb-findings/03023020): Environmental issues › Physical environment · Effect on operation; cases with it: [Robinson Helicopter R44, 2 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md?model=7640120), [All aircraft, 264 cases](https://openairdocs.org/ntsb-findings/03023020/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: Low altitude operation/event](https://openairdocs.org/ntsb-events/220); 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) - [Maneuvering-low-alt flying: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) (defining event); cases with it: [Robinson Helicopter R44, 1 case](https://openairdocs.org/ntsb-events/241/sequence.md?model=7640120), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R44, 56 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640120), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Maneuvering-low-alt flying: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Robinson Helicopter R44, 13 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=7640120), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot in the skid-equipped helicopter reported that he had performed an agricultural application flight. The helicopter was within 100 lbs of the maximum gross weight at the time of the accident. The helicopter was headed south, and the pilot made a left turn to the west, and the helicopter began to settle with power. The pilot noticed the low rotor rpm, and the helicopter touched down on the soft dirt surface and rolled over. The helicopter sustained substantial damage to both rotor drive systems and the fuselage and tailboom. In an interview with National Transportation Safety Board investigator-in-charge, the pilot stated that the helicopter was about 20 ft above ground level when he noticed the low rotor rpm horn and that the airspeed was about 20 knots. He recalled that, when he made the left turn, he was operating with a tailwind. He added that the design of the hopper was not approved by the Federal Aviation Administration to be jettisoned. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. Additional Information According to the Federal Aviation Administration (FAA) Helicopter Flying Handbook FAA-8083-21A (HFH) (pg. 2-4, para. 5), turns in a helicopter increase the load factor exponentially, ultimately increasing the power requirement that is necessary to maintain the helicopter's altitude. Left pedal turns increase the quantity of anti-torque produced by the tail rotor, by demanding additional power from the 260-brake horsepower engine. Pilot flight control inputs demanding more power than the engine is capable of producing, with respect to the atmospheric conditions, adversely affects the helicopters ability to sustain its altitude. Available engine power is directly correlated to main and tail rotor RPM. FAA-8083-21A (pg. 7-2, para. 5), "Factors Affecting Performance," stated: The wind direction is also an important consideration. 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. FAA-8083-21A (pg. 2-4, para. 6), "Weight," stated: To overcome this additional load factor, the helicopter must be able to produce more lift. If excess engine power is not available, the helicopter either descends or has to decelerate in order to maintain the same altitude. The load factor and, hence, apparent gross weight increase is relatively small in banks up to 30°. Even so, under the right set of adverse circumstances, such as high DA, turbulent air, high gross weight, and poor pilot technique, sufficient or excess power may not be available to maintain altitude and airspeed. FAA-8083-21A (pg. 2-5, para. 1), "Weight," further stated: Regardless of howmuch weight one can carry or the engine power that it may have, they (helicopters) are all susceptible to aerodynamic overloading. Unfortunately, if the pilot attempts to push the performance envelope the consequence can be fatal. Aerodynamic forces effect every movement in a helicopter, whether it is increasing the collective or a steep bank angle. Anticipating results from a particular maneuver or adjustment of a flight control is not good piloting technique. Instead pilots need to truly understand the capabilities of the helicopter under any and all circumstances and plan to never exceed the flight envelope for any situation. ## Factual narrative The pilot in the skid-equipped helicopter reported that he had performed an aerial application flight. The helicopter was within 100 pounds of the maximum gross weight at the time of the accident. The helicopter was headed south and the pilot made a left turn to the west and began to settle with power. The pilot noticed the low rotor revolutions per minute (RPM) and the helicopter touched down on the soft dirt surface and rolled over. The helicopter sustained substantial damage to both rotor drive systems, fuselage and tailboom. In an interview with National Transportation Safety Board investigator-in-charge the pilot stated that the helicopter was about 20 feet above ground level when he noticed the low rotor RPM horn and the airspeed was about 20 knots. He recalled that when he made the left turn, he was operating with a tailwind. He added that the design of the hopper was not approved by the Federal Aviation Administration to be jettisoned. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. Additional Information According to the Federal Aviation Administration (FAA) Helicopter Flying Handbook FAA-8083-21A (HFH) (pg. 2-4, para. 5), turns in a helicopter increase the load factor exponentially, ultimately increasing the power requirement that is necessary to maintain the helicopter's altitude. Left pedal turns increase the quantity of anti-torque produced by the tail rotor, by demanding additional power from the 260-brake horsepower engine. Pilot flight control inputs demanding more power than the engine is capable of producing, with respect to the atmospheric conditions, adversely affects the helicopters ability to sustain its altitude. Available engine power is directly correlated to main and tail rotor RPM. The FAA Helicopter Flying Handbook FAA-8083-21A (pg. 7-2, para. 5) per the section entitled Factors Affecting Performance: The wind direction is also an important consideration. 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. The FAA Helicopter Flying Handbook FAA-8083-21A (pg. 2-4, para. 6) entitled Weight, asserts: To overcome this additional load factor, the helicopter must be able to produce more lift. If excess engine power is not available, the helicopter either descends or has to decelerate in order to maintain the same altitude. The load factor and, hence, apparent gross weight increase is relatively small in banks up to 30°. Even so, under the right set of adverse circumstances, such as high DA, turbulent air, high gross weight, and poor pilot technique, sufficient or excess power may not be available to maintain altitude andairspeed. The FAA Helicopter Flying Handbook FAA-8083-21A (pg. 2-5, para. 1) entitled Weight, further states: Regardless of how much weight one can carry or the engine power that it may have, they (helicopters) are all susceptible to aerodynamic overloading. Unfortunately, if the pilot attempts to push the performance envelope the consequence can be fatal. Aerodynamic forces effect every movement in a helicopter, whether it is increasing the collective or a steep bank angle. Anticipating results from a particular maneuver or adjustment of a flight control is not good piloting technique. Instead pilots need to truly understand the capabilities of the helicopter under any and all circumstances and plan to never exceed the flight envelope for any situation. ## Aircraft - Registration: [N4534G](https://openairdocs.org/deregistered/N4534G-2018-11-06), registration cancelled 2018-11-06, S/N 2034, built 2009 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER R44 (UNDESIGNAT) - Registry model: [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44) (registry code 7640120) (OpenAirDocs) - Registry engine: [Lycoming O-540-F1B5](https://openairdocs.org/engine/lycoming-o-540-f1b5) (registry code 42353, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 2034 - Year built: 2009 - Engines: LYCOMING O-540-F1B5 235 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Hammond Charlie D - Registered owner: Hammond Charlie D - Airworthiness certificate: Standard, Normal - Departed: CXL, Calexico, CA - Destination: CXL, Calexico, CA - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 60; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review June 23, 2016; seat: left; restraint: 3-point; flight hours: 30,000 total, 1,500 in this make and model, 200 in the last 90 days, 50 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 250° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 57 °F, dew point 43 °F - Altimeter: 29.95 inHg - Observed at: KIPL, 10 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 20170213001649A](https://openairdocs.org/incident/20170213001649A), Feb 13, 2017: Robinson Helicopter R44, Holtville, CA, Destroyed. Pilot was making a turn after completing an application. Pilot appears to have experienced settling with power condition. Pilot noticed rotor RPM was too low… ## Docket (3 files) The files NTSB released with the investigation on August 30, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94756. 1.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 666 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40455706&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Memorandum for Record – Telephone Interview, PIC (item 2, .PDF, 135 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40455707&FileExtension=.PDF&FileName=Memorandum%20for%20Record%20%E2%80%93%20Telephone%20Interview,%20PIC-Master.PDF - Photo (item 3, .PDF, 397 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40455708&FileExtension=.PDF&FileName=Photo-Master.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.