ANC03LA082 · Hughes 369D
Hughes 369D · Accident: partial loss of engine power (non-mechanical) while maneuvering
From Ketchikan (Temsco H) Heliport (17AK) to Ketchikan, AK
Event
- NTSB case
- ANC03LA082
- 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
- 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
Hughes 369D
- 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
- N1091S
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Ketchikan (Temsco H) Heliport (17AK), Ketchikan, AKTo Ketchikan, AK
- 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
- Maneuvering
- 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 (non-mechanical)
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- 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
- Company maintenance personnel › Maintenance, installation, inadequate
- Turboshaft engine, gas generator ovrspd sensor/gov › Disconnected
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The commercial certificated pilot was conducting an on-demand air taxi flight in a turbine-powered helicopter. While performing an aerial survey, about 100 feet agl, the engine-out annunciator sounded, and the pilot entered an autorotation. As the helicopter touched down in a small clearing, the pilot had the collective pitch control full up to cushion the landing. When the helicopter touched down, the engine power suddenly surged, and the helicopter then began to climb. During the pilot's efforts to control the helicopter, the main rotor blades collided with several trees, and the blades then severed the tail boom. Following the collision with the trees, the pilot rolled the throttle to the off position, but the engine would not shut-down. He then pulled the emergency fuel shut off. Examintion of the helicopter revealed that a bolt, used to connect the N2 governor input arm to an airframe mounted bellcrank, was missing. The bellcrank is connected to the helicopter's collective control linkage. As the pilot moves the collective control, through the bellcrank and governor input arm, engine power increases or decreases. The bolt is normally retained by a castellated nut, and then secured in-place by a cotter pin. Company personnel returned to the accident scene and located the missing bolt and nut lying on the ground, under the location where the engine access doors were opened during an inspection of the engine, before the helicopter was removed from the accident scene. Also found was a cotter pin with one broken side, but it could not be determined if the broken cotter pin was the missing pin from the bolt. The most recent inspection of the helicopter was a 100 hour inspection, conducted by company personnel, 51.8 service hours before the accident. Numerous company pilots had flown the helicopter before the accident. In addition, each pilot conducted an inspection of the helicopter before beginning flight operations. On the day of the accident, the helicopter had flown about 2.5 hours before the accident.
Probable cause
The improper installation of a bolt in the gas generator governor linkage by company maintenance personnel, which resulted in a loss of the bolt, a loss of engine power while maneuvering, and subsequent forced landing and collision with trees. Factors contributing to the accident were an inadequate preflight inspection by the pilot, and an uncommanded surge in engine power.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ANC03LA082
- Event ID
- 20030804X01254
- Case number
- ANC03LA082
- 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: 9d102a6cab61e7df77b4e94580eab14eb48d662b87c5acc96076794579993208; retrieved 2026-09-18T15:43:59.125Z.