ERA14LA223 · Messerschmitt-Bolkow-Blohm BK 117 A-4
Mercy Flight Messerschmitt-Bolkow-Blohm BK 117 A-4 · Accident: part(s) separation from aircraft en route
From 7NK9 · Buffalo, NY to Olean General Heliport (5NK4)
Event
- NTSB case
- ERA14LA223
- 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
- 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
Messerschmitt-Bolkow-Blohm BK 117 A-4
- Aircraft type
- Messerschmitt Bolkow Blohm BK-117
- 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
- N504TJ
- Operator
- Mercy Flight
- Onboard fatalities
- Unknown
- Route
- From 7NK9 · Buffalo, NYTo Olean General Heliport (5NK4), Olean, NY
- Aircraft age
- About 43 years (built 1971)
- 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
- En route · cruise
- 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
- Part(s) separation from aircraft
- 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 structures
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that, during a repositioning flight of the emergency medical services helicopter and while at cruise altitude, the flight nurse notified him and the paramedic that the left cabin door had partially opened. As the flight nurse and paramedic were attempting to close the door, it dislodged from the lower track assembly, pivoted up, and struck the main rotor system; the door subsequently separated from the helicopter. The pilot then initiated a forced landing to a field.
Examination of the door assembly revealed that both of the lower door's bracket guides and the aft lower catcher and guide assemblies were worn and that the door's upper sliders were worn down to their minimum tolerances. The Airplane Maintenance Manual states that, if one of the two sliders does not meet the minimum tolerance, "both sliders must be replaced with new ones." A review of the maintenance logbook revealed that the door assembly had been inspected 127 hours before the accident in accordance with an alert service bulletin but that no anomalies with the door assembly were noted at that time.
Probable cause
Wear in the left cabin door assembly parts, which resulted in the door partially opening in flight, dislodging from the lower door track assembly, and then separating from the helicopter.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA14LA223
- Event ID
- 20140505X93424
- Case number
- ERA14LA223
- 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. 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: 4459c1125ebe4baba2753ffa6d1d125154d72525302cb62b1b5ceca00aa37653; retrieved 2026-09-15T23:34:56.753Z.