ANC21LA003 · Hughes 369 D
Windward Aviation Hughes 369 D · Accident: loss of engine power (partial) en route
From Kawaihapai Airfield (PHDH) to Kahului International Airport (PHOG)
Event
- NTSB case
- ANC21LA003
- 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
- Event fatalities
- Unknown
- 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
Hughes 369 D
- Aircraft type
- Hughes 369
- 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
- N58251
- Operator
- Windward Aviation
- Onboard fatalities
- Unknown
- Route
- From Kawaihapai Airfield (PHDH), Waialua, HITo Kahului International Airport (PHOG), Kahului, HI
- Aircraft age
- About 42 years (built 1978)
- 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
- En route
- Defining eventThe 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
- Loss of engine power (partial)
- 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
- Aircraft › Aircraft systems
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
During longline operations, the helicopter lost partial power and the main rotor rpm decreased. The pilot jettisoned the external load and the helicopter impacted trees, resulting in substantial damage. The engine continued to run after impact, and the pilot performed an emergency engine shutdown.
Examination revealed that the start fuel pump was damaged. The circlip and pin that held the flapper valve in place in the bypass inlet were missing, and the flapper valve was wedged against the sidewall of the bypass inlet, obstructing about 50% of the discharge port. The pin was located in the fuel line between the start fuel pump and the engine-driven fuel pump; the circlip was not found.
No other mechanical malfunctions were found that would have precluded normal operation.
The pin found in the fuel line and obstruction from the flapper valve located in the start fuel pump likely induced restricted fuel flow from the engine-driven fuel pump to the engine, which resulted in a partial loss of engine power.
Based on the available evidence, the reason for the separation of the circlip from the pin could not be determined.
Probable cause
A partial loss of engine power due to an obstructed fuel line as a result of the separation of the circlip from the pin used on the fuel start pump. The reason for the circlip separation could not be determined based on the available evidence.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ANC21LA003
- Event ID
- 20201028102204
- Case number
- ANC21LA003
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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, cause areas. 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: 149f1fb0852ad8b81f0c735a8b0ac937d6fc168146c49c7c985d205b238a2f42; retrieved 2026-09-16T13:18:20.786Z.