SEA03FA169 · Aerospatiale AS350D
Aerospatiale AS350D · Accident: total loss of engine power (mechanical failure) while maneuvering
From Craigmont Municipal Airport (S89) to an unrecorded destination
Event
- NTSB case
- SEA03FA169
- 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
Aerospatiale AS350D
- 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
- N57731
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Craigmont Municipal Airport (S89), Craigmont, IDTo not recorded
- 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 133: Rotorcraft Ext. Load
- 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 · hover out of ground effect
- 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
- Total 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
- Turbine assembly, ring › Warped
- Turbine assembly, turbine blade › Fatigue
- Turboshaft engine, gas generator turbine › Overtemperature
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot had just maneuvered the helicopter for a water pickup for firefighting and was at an altitude of 100-150 feet above ground transitioning to forward flight (outside the height-velocity envelope) when the engine failed. He executed an autorotation to a hard landing as rotor speed bled off. Post accident examination of the engine revealed all the airfoils of the first stage turbine wheel were fractured/damaged and many of the fracture surfaces exhibited features indicative of fatigue progression. Fluorescent penetrant inspection revealed multiple cracks extending onto the rim faces and radial sectioning of several of the stage one turbine airfoils revealed intergranular cracks within the airfoils as well as cracks in the rim area consistent with exposure to temperature spikes and/or elevated operating temperatures. Examination of the second stage turbine nozzle assembly revealed evidence of both thermal distress and mechanical damage and the first stage blade track exhibited damage and deformation throughout its circumference. The diameter and run-out of both the first stage and second stage blade tracks revealed an out of round (warped) condition. Testing of the ToT gauge revealed an out of calibration condition between true input temperature and the temperature displayed on the gauge. The disparity increased as true temperature increased with the gauge reading on the low side (lower than true operating temperatures). Post accident examination revealed metal particulates bridging the contacts of the engine chip light plug. Testing of the warning system revealed a discontinuity within the airframe which prevented the chip light from operating.
Probable cause
An over temperature condition within the gas generator turbine which led to first stage turbine blade fatigue as well as first stage blade track warping and consequent blade tip rub. The fatigue and blade tip rub ultimately led to blade separation and failure of the engine. Contributing factors were the out of calibration condition of the turbine outlet temperature gauge and the non-operational engine CHIP warning light system. An additional factor was insufficient rotor RPM while conducting an autorotation.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA03FA169
- Event ID
- 20030903X01441
- Case number
- SEA03FA169
- 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: fa6811d478656d56488eb40cfcf0c6e2b13177eb3ad23cccd996c4ed9d4e4369; retrieved 2026-09-21T09:24:21.161Z.