Flight AT1200 · Aerospatiale AS350-D
Aerospatiale AS350-D · Accident: partial loss of engine power (mechanical failure) en route
From Hilo International Airport (ITO) to Waimea Kohala Airport (MUE)
Event
- NTSB case
- LAX94FA317
- 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
- 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 AS350-D
- 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
- N889AT
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Hilo International Airport (ITO), Hilo, HITo Waimea Kohala Airport (MUE), Waimea, HI
- 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 · 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
- Partial loss of engine power (mechanical 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
- Bleed air system, fittings › Fatigue
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
DURING A SIGHTSEEING HELICOPTER TOUR FLIGHT AT 1200 FEET AGL, THE PILOT HEARD AND THEN NOTICED A DECREASE IN THE MAIN ROTOR RPM. THE PILOT BEGAN A PRECAUTIONARY LANDING TO A BOULDER-COVERED LEDGE ABOUT 50 FEET FROM THE SURF LINE. WHEN THE PILOT ADDED POWER FOR THE LANDING, THE ENGINE FAILED TO RESPOND AND THE MAIN ROTOR RPM HORN SOUNDED. AFTER TOUCHDOWN, THE MAIN ROTOR AND TAIL ROTOR BLADES STRUCK THE ROCKS AND THE HELICOPTER ROLLED ONTO ITS RIGHT SIDE. A SUBSEQUENT ENGINE EXAMINATION REVEALED A FATIGUE CRACK IN A STEEL 'T' FITTING THAT ATTACHED THE PNEUMATIC PG ACCUMULATOR TO THE POWER TURBINE GOVERNOR. THE CRACK WAS LOCATED IN THE CHANNEL OF THE FITTING WHERE THE ADJACENT NUT RETENTION WIRE IS WRAPPED. A METALLURGICAL EXAMINATION REVEALED NO OTHER CONDITIONS THAT MAY HAVE CONTRIBUTED TO THE INITIATION OF THE CRACK.
Probable cause
a fatigue crack in the 'T' fitting on the power turbine governor pneumatic accumulator. A factor was the rough, rock-covered landing area.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX94FA317
- Event ID
- 20001206X02064
- Case number
- LAX94FA317
- 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: eafb0767b94cd15360482261515ab2512f6a7a8682cd474c3bcda663d6215f95; retrieved 2026-09-18T18:10:11.793Z.