# NTSB CEN17LA290: Helicopteres Guimbal Cabri G2, N722TX, Beaumont, TX, July 28, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 28, 2017, 15:32 local (20:32 UTC) - Place: Beaumont, TX - Coordinates: 30.070278, -94.214996 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=30.0703&lon=-94.2150&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: Minor injuries - Injuries: 2 minor - Status: Completed, report December 19, 2018 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards - NTSB case key (mKey): 95696 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN17LA290 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95696/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95696 - Page: https://openairdocs.org/ntsb/CEN17LA290 ## Probable cause The flight instructor's low-altitude maneuvering, which exceeded the helicopter's performance capability in the high-density altitude conditions and resulted in a loss of control. ## 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 · Instructor/check pilot (probable cause); cases with it: [Helicopteres Guimbal CABRI G2, 11 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=9000001), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Aircraft capability](https://openairdocs.org/ntsb-findings/01061000): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [Helicopteres Guimbal CABRI G2, 1 case](https://openairdocs.org/ntsb-findings/01061000/cases.md?model=9000001), [All aircraft, 57 cases](https://openairdocs.org/ntsb-findings/01061000/cases.md) - [Temp/humidity/pressure: high density altitude](https://openairdocs.org/ntsb-findings/03031020): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Helicopteres Guimbal CABRI G2, 1 case](https://openairdocs.org/ntsb-findings/03031020/cases.md?model=9000001), [All aircraft, 278 cases](https://openairdocs.org/ntsb-findings/03031020/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: [Helicopteres Guimbal CABRI G2, 7 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=9000001), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Helicopteres Guimbal CABRI G2, 10 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=9000001), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The student pilot was practicing basic hovering skills under the supervision of the flight instructor. Due to the high air temperature and minimal airflow over the engine, the engine oil temperature had increased beyond the approved limits. The flight instructor decided to fly a low-altitude circuit along the perimeter of the airport to increase the airflow and cool the engine. The low-altitude circuit was performed at an altitude of about 100 ft above ground level and at a speed of about 60 knots. About halfway around the circuit, the oil temperature had returned to normal, and all other engine indications were normal at that time. However, during the turn at the southwest corner of the airport, which was about three-quarters of the way around the circuit, the helicopter began to lose altitude and would not respond to the flight instructor's control inputs. The flight instructor was unable to regain control, and the helicopter subsequently impacted the ground. Postaccident examination of the helicopter did not reveal any anomalies consistent with a preimpact failure or malfunction. In addition, the flight instructor stated that there were no issues with the helicopter before the accident. Impact marks showed that the main rotor blades struck the ground before the landing skids, which was consistent with a bank angle of at least 40° at the time of the accident. According to information that the helicopter manufacturer provided, the engine power and helicopter performance required to maintain altitude while maneuvering exceeded the power and performance available with the elevated density altitude conditions at the time of the accident flight, which resulted in a loss of altitude and an impact with the ground. ## Factual narrative On July 28, 2017, at 1532 central daylight time, a Helicopteres Guimbal Cabri G2 helicopter, N722TX, was substantially damaged when it impacted terrain while maneuvering at the Beaumont Municipal Airport (BMT), Beaumont, Texas. The flight instructor and student pilot sustained minor injuries. The helicopter was registered to American Helicopter Leasing Corp and operated by Texas Rotorwing LLC as a Title 14 Code of Federal Regulations Part 91 instructional flight. Day visual meteorological conditions prevailed. The flight was not operated on a flight plan. The local flight originated from BMT about 1500.The flight instructor reported that he and the student had completed three normal approaches and then practiced basic hover skills at the north ramp area of the airport. A high engine oil temperature condition occurred during the hovering maneuver due to the ambient air temperature and the reduced airflow available for engine cooling. To increase engine airflow and reduce the engine temperature, he performed a low altitude circuit at 60 knots, about 100 ft above ground level (agl), around the perimeter of the airport. About halfway around the perimeter, the oil temperature had returned to the normal operating range and all other engine indications were normal at that time. However, during the turn at the southwest corner of the airport, the helicopter began to lose altitude and would not respond to his control inputs. His efforts to regain control were not successful and the helicopter impacted the open grass area on the airport southwest of the runway. The instructor noted that the helicopter was loaded within the gross weight and center-of-gravity limitations. He added that the turns were never more than 45 degrees angle of bank. He reported that there were no anomalies with regard to the helicopter, and that the high temperatures, low wind, and high density altitude likely resulted in the accident. A Federal Aviation Administration inspector responded to the accident site and conducted an examination of the helicopter. The flight instructor informed him that he was completing a turn, during which the helicopter was unable to maintain altitude. The helicopter came to rest on its right side. The main rotor blades were fragmented, and the tail boom was partially separated. Impact marks suggested that the main rotor had struck the ground followed by a landing skid. His examination of the flight control system did not reveal any pre-impact anomalies. Weather conditions reported by the BMT Automated Weather Observing System (AWOS) did not include any wind information. The most recent observation recorded a temperature and dew point of 35 degrees Celsius and 21 degrees Celsius, respectively. The calculated density altitude was about 2,650 feet. Wind conditions reported by the Jack Brooks Regional Airport (BPT) Automated Surface Observing System (ASOS), located about 12 miles southeast of BMT, were variable at 4 knots at the 1453 observation andvariable at 3 knots at the 1553 observation. The maximum engine power was derated as installed in the Cabri G2 helicopter to 145 hp for both takeoff and continuous operation. However, under the accident conditions, the engine was capable of producing approximately 160 hp. Application of full throttle by the pilot would be expected to provide 160 hp under the accident conditions. Engine performance was referenced to the 145 hp continuous limit, with 100% power corresponding to 145 hp and 111% power corresponding to 160 hp. In addition, the helicopter geometry implied that an angle of bank in excess of 40° would result in the main rotors impacting the ground before the landing skids. The helicopter manufacturer stated that at an operating weight of 1,440 lbs. (650 kg) about 90% engine power would be required to maintain an in-ground-effect (IGE) hover at 32 ft agl and 32°C. Application of full throttle (111% power) would have provided a 21% power margin for an IGE hover under the accident conditions. However, maintaining altitude in a 45° bank turn would require a 1.4 load factor which exceeded the available 21% power margin. ## Aircraft - Registration: [N722TX](https://openairdocs.org/deregistered/N722TX-2020-02-28), registration cancelled 2020-02-28, S/N 1171, built 2016 (OpenAirDocs) - Reported make and model: HELICOPTERES GUIMBAL CABRI G2 - Registry model: [Helicopteres Guimbal CABRI G2](https://openairdocs.org/model/helicopteres-guimbal-cabri-g2) (registry code 9000001) (OpenAirDocs) - Registry engine: [Lycoming O-360-J2A](https://openairdocs.org/engine/lycoming-o-360-j2a) (registry code 42314, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 1171 - Year built: 2016 - Airframe hours: 159.9 - Engines: Lycoming O-360-J2A 145 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Texas Rotorwing Academy - Registered owner: American Helicopter Leasing Corp LLC - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, July 1, 2017, 9 hours before - Departed: BMT, Beaumont, TX - Destination: BMT, Beaumont, TX - Airport: BMT, Beaumont Muni - Equipment: Electronic primary flight display, Electronic multifunction display, ADS-B, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 36; injuries: minor; commercial, flight instructor; medical: class 2, without waivers/limitations; last flight review November 8, 2015; seat: left; restraint: 4-point; flight hours: 715 total, 452 in this make and model, 653 as pilot in command, 40 in the last 90 days, 20 in the last 30 days, 0 in the last 24 hours - Student pilot; age 60; injuries: minor; student; seat: right; restraint: 4-point; flight hours: 3 total, 3 in this make and model, 0 as pilot in command, 3 in the last 90 days, 3 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 4,800 ft broken - Temperature: 95 °F, dew point 72 °F - Altimeter: 29.89 inHg - Observed at: BPT, 12 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 20170728015629A](https://openairdocs.org/incident/20170728015629A), Jul 28, 2017: 2016 Helicopters Guimbal CABRI G2, Beaumont, TX, Substantial damage. While performing an air taxi at 100' AGL during a 90 degree left turn the aircraft lost main rotor effectiveness resulting in the aircrafts inability to… ## Docket (8 files) The files NTSB released with the investigation on August 27, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95696. 19.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1 photo, 6.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465975&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - FAA Inspector Statement (item 2, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465976&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement-Master.PDF - Maintenance Records - Airframe (item 3, .PDF, 7.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465977&FileExtension=.PDF&FileName=Maintenance%20Records%20-%20Airframe-Master.PDF - Maintenance Records - Engine (item 4, .PDF, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465978&FileExtension=.PDF&FileName=Maintenance%20Records%20-%20Engine-Master.PDF - Weather Documentation - Surface Observations (item 5, .PDF, 199 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465979&FileExtension=.PDF&FileName=Weather%20Documentation%20-%20Surface%20Observations-Master.PDF - Weather Documentation - Density Altitude (item 6, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465980&FileExtension=.PDF&FileName=Weather%20Documentation%20-%20Density%20Altitude-Master.PDF - Flight Manual Excerpt - Helicopter Geometry (item 7, .PDF, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465981&FileExtension=.PDF&FileName=Flight%20Manual%20Excerpt%20-%20Helicopter%20Geometry-Master.PDF - Flight Manual Excerpt - Engine Limitations (item 8, .PDF, 192 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465982&FileExtension=.PDF&FileName=Flight%20Manual%20Excerpt%20-%20Engine%20Limitations-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.