CEN21LA216 · Aerospatiale AS350 B2 ECUREUIL
Aerospatiale AS350 B2 ECUREUIL · Accident: loss of control in flight while maneuvering
From OKC Will Rogers World Airport (KOKC) to an unrecorded destination
Event
- NTSB case
- CEN21LA216
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- Event fatalities
- Unknown
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Government
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Aerospatiale AS350 B2 ECUREUIL
- Aircraft type
- Aerospatiale AS350
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N841BP
- Operator
- Customs Border and Protection
- Onboard fatalities
- Unknown
- Route
- From OKC Will Rogers World Airport (KOKC), Oklahoma City, OKTo not recorded
- Aircraft age
- About 34 years (built 1987)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Public Aircraft
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of control in flight
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Aircraft › Aircraft oper/perf/capability
- Aircraft › Aircraft systems
- Personnel issues › Action/decision
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot receiving instruction (pilot) and the flight instructor were conducting a training flight in the helicopter. They performed several simulated emergencies, each of which required the helicopter’s hydraulic system to be turned off and then turned back on at the conclusion of the procedure. The hydraulic system was turned off and on using the hydraulic cut-off switch, an unguarded push-button switch mounted on the end of the pilot’s collective stick.
After completing the emergency procedures, the pilot performed four quick stop maneuvers. The flight instructor reported that on the last quick stop, the helicopter slowed normally but then started a left yaw about 25 ft above ground level. The pilot noted the left yaw and attempted to correct it, but his pedal inputs did not stop the yaw. As the pilot tightened his grip on the collective, the hydraulic system turned off, likely due to the pilot inadvertently pressing the hydraulic cut-off switch, and the left yaw rapidly increased to a left spin. According to the flight instructor, the control loads “instantly became excessive,” and he noticed the hydraulic light on the caution warning panel was illuminated. The pilot intentionally pressed the hydraulic cut-off switch a total of three times, but hydraulic pressure was never restored. The flight instructor told the pilot that he was taking control of the helicopter. However, the pilot did not relinquish control. The flight instructor attempted to regain control of the helicopter but was unable to overcome the high control loads.
The helicopter continued to spin, impacted the ground, rolled over, and came to rest on its right side. A postimpact fire consumed most of the helicopter. Although examination of the helicopter was limited due to fire damage, no preimpact abnormalities were identified with helicopter’s airframe and engine.
The US Customs and Border Protection Air and Marine Operations Division reported that the agency’s selection process for the Air Interdiction Agent Program failed to properly identify that the pilot was not qualified for the program.
Because the pilot did not have the qualifications and experience required for the Air Interdiction Agent Program, he did not have the prerequisite skill necessary to critically assess the situation given by the flight instructor. This resulted in the pilot applying improper corrective actions and failing to relinquish control of the helicopter to the flight instructor when directed, which contributed the accident.
Probable cause
The pilot receiving instruction’s untimely and unidentified inadvertent activation of the hydraulic cut-off switch, which turned off the hydraulic system while the helicopter was at slow airspeed followed by a rapid power increase, which resulted in a loss of control. Contributing was the pilot’s failure to relinquish control of the helicopter to the flight instructor when directed.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN21LA216
- Event ID
- 20210513103077
- Case number
- CEN21LA216
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 9ce10dbc67ddc3f42a3d464185664b6acef0e3b621802b75a058ca6dc743beea; retrieved 2026-09-16T14:02:26.566Z.