# NTSB GAA19CA279: Guimbal Cabri, N369PA, St. Louis, IL, May 23, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: May 23, 2019, 14:10 local (19:10 UTC) - Place: St. Louis, IL - Coordinates: 38.570278, -90.154998 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.5703&lon=-90.1550&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-aborted after touchdown: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report April 13, 2020 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 99479 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA19CA279 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99479/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99479 - Page: https://openairdocs.org/ntsb/GAA19CA279 ## Probable cause The flight instructor's improper emergency procedure instruction to the student pilot, which resulted in the student improperly using the throttle to correct the loss of yaw control, which resulted in ground impact and a dynamic rollover. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Helicopteres Guimbal CABRI G2, 3 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=9000001), [All aircraft, 3,969 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Student/instructed pilot (probable cause); cases with it: [Helicopteres Guimbal CABRI G2, 11 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=9000001), [All aircraft, 9,308 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [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, 9,308 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Terrain: wet/muddy terrain](https://openairdocs.org/ntsb-findings/03021035): Environmental issues › Physical environment · Effect on operation (probable cause); cases with it: [Helicopteres Guimbal CABRI G2, 1 case](https://openairdocs.org/ntsb-findings/03021035/cases.md?model=9000001), [All aircraft, 110 cases](https://openairdocs.org/ntsb-findings/03021035/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-aborted after touchdown: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Helicopteres Guimbal CABRI G2, 3 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=9000001), [All aircraft, 4,590 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing-aborted after touchdown: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Helicopteres Guimbal CABRI G2, 6 cases](https://openairdocs.org/ntsb-events/060/sequence.md?model=9000001), [All aircraft, 1,428 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Landing-aborted after touchdown: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Helicopteres Guimbal CABRI G2, 3 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=9000001), [All aircraft, 3,656 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing-aborted after touchdown: 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, 10,154 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Landing-aborted after touchdown: Dynamic rollover](https://openairdocs.org/ntsb-events/231); cases with it: [Helicopteres Guimbal CABRI G2, 1 case](https://openairdocs.org/ntsb-events/231/sequence.md?model=9000001), [All aircraft, 163 cases](https://openairdocs.org/ntsb-events/231/sequence.md) ## Analysis The flight instructor reported that, during a training flight in the helicopter, he briefed the student pilot on the procedures required to land with a simulated stuck left pedal. The student began a descent to enter a shallower-than-normal glidepath to the runway surface, and he completed his final checks for the maneuver and continued the approach. During the approach the flight instructor directed the student pilot to use "throttle manipulation to control the yaw caused by a fixed input on the anti-torque system." Upon contacting the runway, the helicopter veered left, and the instructor chose to abort the landing. As the helicopter lifted off, it began to rapidly yaw left while drifting left of the runway. Recognizing that the helicopter was in a spin, they attempted to correct by leveling the helicopter long enough to regain tail rotor authority. The helicopter's left skid impacted mud on the left side of the runway, and the helicopter rolled onto its left side. The helicopter sustained substantial damage to the main rotor, fuselage, and tailboom. The instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. A manufacturer's service letter, SL 19-002 A, stated, "During in-flight tail rotor control failure simulation, pilots should never use the twist grip to control yaw." Therefore, the flight instructor's direction to the student to use the throttle to correct the yaw was incorrect and led to ground impact and a dynamic rollover. ## Factual narrative The helicopter flight instructor reported that, during a training flight, he briefed the student pilot on the procedures required to land with a simulated stuck left pedal. The student began a descent to enter a shallower-than-normal glide path to the runway surface, and he completed his final checks for the maneuver and continued the approach. Upon contacting the runway, the helicopter veered to the left, and the instructor elected to abort the landing. As the helicopter lifted off, it began to yaw to the left at a rapid rate, while drifting to the left of the runway. Recognizing the helicopter was in a spin, they attempted to correct by leveling the helicopter "long enough for the aircraft to regain tail-rotor authority." The helicopter's left skid impacted the mud on the left side of the runway and the helicopter rolled onto its left side. The Federal Aviation Administration's Helicopter Flying Handbook, FAA-H-8083-21A, provides information and guidance in a section titled "Landing – Stuck Neutral or Right Pedal" which stated in part: The landing profile for a stuck neutral or a stuck right pedal is a low-power approach terminating with a running or roll-on landing. The approach profile can best be described as a shallow to normal approach angle to arrive approximately 2–3 feet landing gear height above the intended landing area with a minimum airspeed for directional control. During the approach the flight instructor directed the student pilot to "utilize throttle manipulation to control the yaw caused by a fixed input on the anti-torque system." The manufactures service letter, SL 19-002 A, states, "During in-flight tail rotor control failure simulation, pilots should never use the twist grip to control yaw." The helicopter sustained substantial damage to the main rotor, fuselage and tail-boom. The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. The automated weather observation station located on the airport reported that, about the time of the accident, the wind was variable at 4 knots. ## Aircraft - Registration: [N369PA](https://openairdocs.org/deregistered/N369PA-2020-07-15), registration cancelled 2020-07-15, S/N 1109, built 2015 (OpenAirDocs) - Reported make and model: 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: 1109 - Year built: 2015 - Airframe hours: 1839.8 - Engines: LYCOMING O-360-J2A 145 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: D H Helicopter Inc - Registered owner: D H Helicopter Inc - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, May 8, 2019 - Departed: CPS, St Louis, IL - Destination: CPS, St. Louis, IL - Airport: CPS, St Louis Downtown, runway 30R, 5,301 × 75 ft, concrete - Equipment: Electronic multifunction display, Electronic primary flight display, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 32; injuries: none; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review August 27, 2018; seat: left; flight hours: 653 total, 425 in this make and model, 545 as pilot in command, 135 in the last 90 days, 32 in the last 30 days, 1 in the last 24 hours - Student pilot; age 27; injuries: none; student; medical: class 2, without waivers/limitations; seat: right; flight hours: 62 total, 62 in this make and model, 11 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Temperature: 79 °F, dew point 70 °F - Altimeter: 30.05 inHg - Observed at: KCPS ## 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 20190523005059A](https://openairdocs.org/incident/20190523005059A), May 23, 2019: Helicopteres Guimbal CABRI G2, Cahokia, IL, Substantial damage. The student and instructor were attempting to perform a simulated stuck pedal emergency procedure at St. Louis Downtown Airport. After touchdown, while still… ## Docket (3 files) The files NTSB released with the investigation on July 18, 2019, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99479. 1.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 840 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40474237&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Guimbal Service Letter 19-002A (item 2, .PDF, 317 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40474238&FileExtension=.PDF&FileName=Guimbal%20Service%20Letter%2019-002A-Master.PDF - Accident Photos (item 3, .PDF, 2 photos, 388 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40474239&FileExtension=.PDF&FileName=Accident%20Photos-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.