DEN00LA045 · Bell 212
Bell 212 · Accident: airframe, component or system failure while maneuvering
From 43U to an unrecorded destination
Event
- NTSB case
- DEN00LA045
- 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
- 0
- 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 212
- Aircraft type
- Bell 212
- 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
- N212HQ
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From 43UTo not recorded
- 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 133: Rotorcraft Ext. Load
- 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
- 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
- Manufacturer › Inadequate quality control
- Rotor drive system, main rotor mast(drive shaft) › Failure, total
- Rotor drive system, main rotor mast(drive shaft) › Fatigue
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While in level flight approximately 120 feet above ground level, carrying an external load of logs, the main rotor mast separated from the helicopter. The fuselage descended into a tree covered slope and broke into three sections. The pilot received serious injuries. Laboratory examination of the main rotor mast provided evidence the mast failed in fatigue at the lower ring groove of the damper splines where burrs were left during machining of the part. Retirement requirements for the mast were 15,000 flight hours or 300,000 RIN (retirement index number). The mast had 5,644.4 hours with the last overhaul being done at 3,660.8 hours. The FAA calculated the RIN number to be 291,065.
Probable cause
Failure of the main rotor mast due to fatigue that resulted from inadequate quality assurance during the manufacturing process.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN00LA045
- Event ID
- 20001212X20352
- Case number
- DEN00LA045
- 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. 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: 34755da7ac7632b34e6afbb61d0cb0137fec10b0cbf1df963b92ae262623e940; retrieved 2026-09-21T10:43:36.897Z.