NYC01LA088 · Bell 206 L-1
EMS AirService of New York Bell 206 L-1 · Accident: airframe, component or system failure en route
From Canandaigua Airport (D38) to Marcellus Airport (NK71)
Event
- NTSB case
- NYC01LA088
- 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
Bell 206 L-1
- 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
- N2138Y
- Operator
- EMS AirService of New York
- Onboard fatalities
- Unknown
- Route
- From Canandaigua Airport (D38), Canadaigua, NYTo Marcellus Airport (NK71), Marcellus, NY
- Aircraft age
- Not recorded
- 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 · climb to cruise
- First occurrenceThe 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
- Airframe, component or system failure
- 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
- Miscellaneous, bolt/nut/fastener/clamp/spring › Missing
- Rotor drive system, tail rotor drive shaft coupling › Failure, partial
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The Bell 206 L-1 helicopter was on a positioning flight. While in cruise flight, the pilot added power for a slow climb, and experienced multiple "bangs" and yawing. He reduced power, determined that he had lost tail rotor thrust, and set up for a precautionary landing in a wooded area. Upon touchdown, the helicopter rolled over. A bolt was found missing from the Thomas coupling located between the aft end of the aft short shaft, and the foward segment of the tail rotor drive shaft. In addition, the bracket for the forward hanger bearing was fractured. Metallurgical examination of the flange from the Thomas coupling with the missing bolt, revealed thread imprint marks on the inside of the bolt hole bore, and lipped material at the edge of the bolt hole bore. The hanger bearing mount had failed in overstress with no evidence of progressive cracking. The helicopter had been operated for 15.2 hours since the Thomas coupling had been disassembled and put back together. The mechanic reported that he had reused the bolts and self-locking nuts, and tightened them to the proper torque. The missing nut and bolt were not recovered. A check of the FAA database for SDRs revealed no other occurrences in the preceding 5 years.
Probable cause
the loss of a bolt in a Thomas coupling on the tail rotor drive shaft, for undetermined reasons, during climb, while operating over unsuitable terrain.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record NYC01LA088
- Event ID
- 20010330X00681
- Case number
- NYC01LA088
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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. 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: ede61ea6ad8ae94d5486592aef349f7a656010d6b6a4f3a6ecf4eb024ca6d020; retrieved 2026-09-21T10:10:46.833Z.