LAX06LA030 · Bell 47D1
Bell 47D1 · Accident: airframe, component or system failure en route
From Rancho Murieta Airport (RIU) to RIU
Event
- NTSB case
- LAX06LA030
- 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 47D1
- Aircraft type
- Bell 47
- 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
- N16356
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Rancho Murieta Airport (RIU), Rancho Murieta, CATo RIU
- 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 · 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 › Fatigue
- Rotor system, tail rotor hub pitch link › Separation
- Rotor system, tail rotor hub › Separation
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The helicopter landed hard following the in-flight separation of the tail rotor assembly. During cruise, the pilot felt a vibration in the anti-torque pedals and attempted to make a precautionary landing in an open field. The tail rotor assembly separated prior to the pilot reaching the landing spot and the helicopter started to rotate and landed hard. The helicopter bounced back into the air, struck the ground again with the transmission bending over the cockpit area. Examination of the tail rotor assembly revealed that one of the pitch change links bolts had separated with the shank portion broken from the threaded portion of the bolt. A metallurgical examination of the bolt revealed that the fracture surface of the shank portion had been subjected to reverse bending fatigue. The arced lines were symmetrical on each side of the shank that culminated in a thin, dark, hourglass-shaped region in the center of the two arced lines. Burnishing observed on the fracture was typical of failures in bolts that have not been properly preloaded.
Probable cause
a separation of the tail rotor assembly due to the reverse bending fatigue fracture of a tail rotor pitch change link bolt, resulting in a loss of control of the helicopter, and a hard landing during the uncontrolled descent.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX06LA030
- Event ID
- 20051123X01885
- Case number
- LAX06LA030
- 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: cf7d060a5944af7d4f06a5bd2f93f1a80cfe37f0707b08260cefec81d25dfcc7; retrieved 2026-09-21T09:01:40.454Z.