ENG20LA031 · Airbus Helicopters AS350 B3
Macneil Aviation Airbus Helicopters AS350 B3 · Incident: flight control system malfunction/failure on approach
From Palm Beach County Park Airport (LNA) to an unrecorded destination
Event
- NTSB case
- ENG20LA031
- 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
- Incident
- 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
- API-reported fatalities
- 0 · all aircraft and ground
- 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
- General aviation
- 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
Airbus Helicopters AS350 B3
- Aircraft type
- Airbus 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
- N1WT
- Operator
- Macneil Aviation
- Onboard fatalities
- Unknown
- Route
- From Palm Beach County Park Airport (LNA), West Palm Beach, FLTo not recorded
- Aircraft age
- About 2 years (built 2018)
- 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
- Part 91: General Aviation
- 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
- Approach · VFR pattern downwind
- 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
- Flight control system malfunction/failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Aircraft › Aircraft systems
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The No. 2 hydraulic system (HYD2) pulley bearing likely failed due to being installed skewed onto its pulley, resulting in abnormal bearing loads which led to its premature failure. The plastic deformation observed on the raceways and rolling elements, as well as contact damage on the bearing cage, were consistent with sliding of the rolling elements against the raceways and cage due to abnormal loading and forced rotation of a seized bearing. The seizure of the HYD2 pulley bearing led to the deterioration of the drive belt, resulting in its failure and the subsequent loss of hydraulic pressure in HYD2. Loss of hydraulic assistance from HYD2, which included the tail rotor servo control, resulted in higher pedal forces to control the helicopter in the yaw axis. It is likely the HYD2 pulley bearing did not show obvious visual evidence of deterioration during past inspections, including the last scheduled inspection about 13 flight hours prior to the incident, and visual detection of the deteriorating bearing may not have been possible without removal of the bearing from the pulley.
Probable cause
Seizure of the hydraulic pump pulley bearing due to its improper installation by the manufacturer, leading to a failure of the hydraulic pump belt and the resultant partial loss of hydraulic assistance to the pedals.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ENG20LA031
- Event ID
- 20200504X54503
- Case number
- ENG20LA031
- 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, coordinates, cause areas, damage. 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: ac4da33d5539a706fc93ac1ff45e6e4e847a4d77ca27568cd51ebf55686a10fc; retrieved 2026-09-16T11:32:58.467Z.