Air Evac EMS Bell 206 L1 accident
Bell 206 L1 · Accident: loss of engine power (partial) en route
From Northeast Regional Medical Center Heliport (MU92) to Boone Hospital Center Heliport (91MO)
Event
- NTSB case
- CEN20LA113
- 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
- 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
- Charter & commuter
- 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
Bell 206 L1
- Aircraft type
- Bell 206
- 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
- N32AE
- Operator
- Air Evac Ems
- Onboard fatalities
- Unknown
- Route
- From Northeast Regional Medical Center Heliport (MU92), Kirksville, MOTo Boone Hospital Center Heliport (91MO), Columbia, MO
- Aircraft age
- About 41 years (built 1979)
- 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 135: Air Taxi & Commuter
- 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
- En route
- 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 engine power (partial)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft power plant
- Not determined › Not determined
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot of the helicopter air ambulance flight reported that, while en route on the night patient transfer flight, he received low rotor rpm warnings and engine power dropped below 90%. He reduced collective and turned toward a field to perform a precautionary landing, during which the helicopter touched down hard, resulting in substantial damage to the tail boom. A postaccident examination of the helicopter revealed that a pneumatic line, which had been leak-checked about 115 hours before the accident flight, had separated near its filter connection. A leak in the pneumatic line can cause the engine control system to enter a sub-idle fuel flow condition, resulting in a loss of engine power.
An examination of the pneumatic line and filter revealed that the tube had fractured completely through at the toe of the weld between the tube and its filter fitting. Surface smearing was present on sections of the separation; however, the separation exhibited surfaces consistent with fatigue that initiated near the top of the tube. The tube's outer diameter surface near the elbow separation exhibited rub damage. A red ribbed hose was present in the engine bay near the tube separation and the ribbed hose exhibited discoloration on its outer surface consistent with rubbing against the pneumatic tube. One weld exceeded its component specification; the remaining tube and weld measurements met their component specifications. The tube, fitting, and weld materials met specifications.
According to the engine manufacturer, the accident was the first occurrence of a separation involving this revision of the pneumatic line over 17 million fleetwide flight hours. The cause of the fatigue could not be attributed to the hose and pneumatic tube rubbing or any other issue, and the reason for the failure could not be determined based on the available information.
Probable cause
The fatigue failure of the pneumatic line for reasons that could not be determined, which resulted in a loss of engine power and subsequent hard landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN20LA113
- Event ID
- 20200305X41622
- Case number
- CEN20LA113
- 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: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2020-03-05.
- API snapshot SHA-256: c848d8accb05de2ee2b4a22a8df9fed004a8e764cc0fa7b4e05d5a76cb4e04be; retrieved 2026-09-16T11:14:37.339Z.