CEN12LA525 · Bell 214ST
Bell Helicopter Textron Bell 214ST · Accident: flight control system malfunction/failure while maneuvering
From Arlington Municipal Airport (KGKY) to Arlington Municipal Airport (KGKY)
Narrative check · The NTSB narrative appears to contradict this record's departure or destination. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- CEN12LA525
- 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 214ST
- Aircraft type
- Bell 214
- 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
- N409SB
- Operator
- Bell Helicopter Textron
- Onboard fatalities
- Unknown
- Route Possible conflict
- From Arlington Municipal Airport (KGKY), Arlington Muni, TXTo Arlington Municipal Airport (KGKY), Arlington Muni, TX
- 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
- Maneuvering
- 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
- Substantial
Cause areas
- Aircraft › Aircraft propeller/rotor
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The helicopter was on its third test flight when the tail rotor 90-degree gearbox broke in two and separated from the helicopter. The crew conducted an autorotation to a field, and the helicopter came to rest on its side. Examination of the helicopter and components revealed that one of the tail rotor's two counterweight bellcranks and associated hardware were missing. Impact marks consistent with a counterweight bellcrank were found at the base of its associated tail rotor blade and on the aft right side of the helicopter. The remaining counterweight bellcrank was in place; however, the cotter pin for the castellated nut was missing. A review of the aircraft maintenance records revealed that the tail rotor assembly had been removed and reinstalled after the installation of test instrumentation. The maintenance records lacked specific details on whether the unit and its components were previously handled as a subassembly or as individual components when the tail rotor assembly was initially removed. Because the records did not indicate whether the unit should be handled as individual parts, the tail rotor was reinstalled as a complete subassembly, meaning that individual components, such as the nut and cotter pin, were not individually inspected before or after reinstallation on the helicopter. Reinstalling the tail rotor assembly in this manner led to the counterweight bellcrank retaining nut not being properly torqued and secured with a cotter pin.
Probable cause
Maintenance personnel’s failure to properly torque the retaining nut and install the cotter pin that secured the helicopter’s tail rotor counterweight bellcrank. Contributing to the accident was the lack of detailed maintenance records that documented previous maintenance actions.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN12LA525
- Event ID
- 20120807X35254
- Case number
- CEN12LA525
- 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: 1f4a0899da455046c4b8b01abf0e68a7658174a3d2a02c1f64ce132b14ec026c; retrieved 2026-09-15T19:15:54.593Z.