LAX98LA184 · Aerospatiale AS350BA
Aerospatiale AS350BA · Accident: airframe, component or system failure en route
From Lake Arrowhead, CA to Van Nuys Airport (VNY)
Event
- NTSB case
- LAX98LA184
- 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
Aerospatiale AS350BA
- Aircraft type
- Aerospatiale AS350
- 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
- N31621
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Lake Arrowhead, CATo Van Nuys Airport (VNY), Van Nuys, CA
- 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
- Rotor system, tail rotor hub pitch link › Fatigue
Approximate · Estimated position: the centre of Burbank, CA, the place the record names. Not the accident site.
NTSB narrative
The pilot felt a 'violent vibration' and the helicopter began to pitch and yaw. About 5 seconds after the vibration started, the tail rotor gearbox chip light became illuminated. The pilot made a normal approach to a rooftop parking structure and landed. The last 3 feet of the tail boom had separated 360 degrees in circumference. Examination of the tail rotor system revealed one pitch change link disconnected due to a fatigue fracture, which emanated from multiple origins at the inside diameter surface of the loop that is in contact with the bearing assembly. The scrim cloth for the bearing assembly raceway was missing, and the bearing outer raceway contained wear damage approximately 180 degrees around its circumference. A maximum of 0.008 inches of play is allowed in the radial direction between the ball and the pitch change link assembly; however, no limit is specified for the axial direction. The pilot reported that he completed a required daily inspection of the aircraft the day before the accident and observed no play in either tail rotor pitch link, nor did he see any cracks. He also reported that he performed a preflight before takeoff on the accident flight and did not note any discrepancies at that time.
Probable cause
The separation of the tail rotor pitch link due to a fatigue fracture, which resulted in the separation of the tailboom.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX98LA184
- Event ID
- 20001211X10347
- Case number
- LAX98LA184
- 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: 6a04b21e079c1161256f990370c8f06d7794ab242736020777337e035217723b; retrieved 2026-09-22T17:42:04.781Z.