Sea-Link Helicopters Aerospatiale AS-350B1 accident
Aerospatiale AS-350B1 · Accident: airframe, component or system failure en route
From an unrecorded airport to OIL TANKER, GM
Event
- NTSB case
- FTW94FA231
- 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
- 4 · 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
- Charter & commuter
- 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 AS-350B1
- Aircraft type
- Aerospatiale AS-350
- 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
- N350WM
- Operator
- Sea-Link Helicopters
- Onboard fatalities
- Unknown
- Route
- From not recordedTo OIL TANKER, GM
- 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 135: Air Taxi & Commuter
- 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
- Destroyed
Cause areas
- Other maintenance personnel › Maintenance, inadequate
- Rotorcraft flight control system, primary servo › Disconnected
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
THE PILOT REPORTED THAT THE HELICOPTER WAS CLIMBING THROUGH '...2,000 FEET WHEN A BUMP SIMILAR TO TURBULENCE WAS FELT. ANOTHER BUMP WAS FELT, FOLLOWED BY A MORE PRONOUNCED BUMP, THEN AIRCRAFT CONTROL WAS LOST.' HE ADDED THAT THE CYCLIC AND COLLECTIVE WERE UNRESPONSIVE. THE HELICOPTER IMPACTED THE WATER IN THE GULF OF MEXICO APRX 11 MILES OFFSHORE. ALL MAJOR COMPONENTS, EXCEPT THE VERTICAL FIN AND TAILROTOR GEARBOX, WERE RECOVERED. DURING A RECONSTRUCTION OF THE HELICOPTER, THE LEFT LATERAL SERVO ROD END WAS FOUND DISCONNECTED FROM THE SERVO EXTENSION. THE THREADS ON THE ROD END WERE INTACT AND APPEARED UNDAMAGED; HOWEVER, ONLY REMNANTS OF THE MATING INTERNAL THREADS IN THE SERVO EXTENSION REMAINED. ALMOST THE ENTIRE THREAD PROFILE WAS WORN AWAY LEAVING ONLY THE THREADED AREA THAT HAD BEEN LOCATED WITHIN THE KEYWAY SLOT OF THE ROD END. THE ZER0-TIME SERVO HAD BEEN INSTALLED 416 FLIGHT-HRS BEFORE THE ACCIDENT. THE LEFT LATERAL SERVO, WHICH IS CONNECTED BY A PUSH ROD TO THE CONTROLS AT THE MAIN ROTOR HEAD, CHANGES THE ATTITUDE OF THE HELICOPTER BY CHANGING THE ANGLE OF ATTACK OF THE MAIN ROTOR BLADES.
Probable cause
INADEQUATE TORQUING OF THE LEFT LATERAL SERVO BY MAINTENANCE PERSONNEL, WHICH ALLOWED IT TO BECOME DISCONNECTED FROM THE CONTROLS, LEADING TO AN IN-FLIGHT LOSS OF CONTROL.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW94FA231
- Event ID
- 20001206X01731
- Case number
- FTW94FA231
- 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: 7e5ae6392360debdab6e3e2aad06b583638deb0bc26380fc02041801735df392; retrieved 2026-09-18T13:48:52.419Z.