ANC21LA038 · Enstrom F-28F
Talaheim Air Service Enstrom F-28F · Accident: powerplant system/component malfunction/failure en route
From Palmer, AK to an unrecorded destination
Event
- NTSB case
- ANC21LA038
- 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
Enstrom F-28F
- Aircraft type
- Enstrom F-28
- 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
- N8627J
- Operator
- Talaheim Air Service
- Onboard fatalities
- Unknown
- Route
- From Palmer, AKTo not recorded
- Aircraft age
- About 32 years (built 1989)
- 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 91: General Aviation
- 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
- Powerplant system/component malfunction/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
- Aircraft › Aircraft propeller/rotor
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
During a helicopter tour flight, the clutch disengage light dimly illuminated, flickered, then fully illuminated. As the pilot began to descend for landing, he felt the belt clutch disengage, and the engine rpm separated from the transmission rpm indicating the helicopter had lost engine power to the rotor system. The pilot entered an autorotation and made a forced landing in a nearby open field. The helicopter touched down with a tailwind of about 13 mph, slid forward and nosed down. A main rotor blade impacted the ground in front of the helicopter followed by a main rotor blade impacting the tail section just forward of the stabilizers, which resulted in substantial damage to the fuselage. A postaccident examination of the helicopter revealed that the main belt drive tensioning system (belt clutch) inadvertently disengaged in flight. Testing found that the disengagement occurred due to inadequate clearance between the clutch handle and the roll pin in the handle bellcrank when the handle was in the stowed position.
As a result of this accident, the helicopter manufacturer issued a service bulletin that clarified the rigging requirements for the clutch handle and allowed for a minor modification to the handle to increase clearance between the handle and the roll pin in the bellcrank.
Probable cause
A loss of drive to the rotor system due to the disengagement of the main belt drive tensioning system, which resulted in a forced landing. The disengagement was due to inadequate clearance between the clutch handle and the roll pin in the handle bellcrank when the handle was in the stowed position.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ANC21LA038
- Event ID
- 20210510103058
- Case number
- ANC21LA038
- 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: 40adeac06761043c3bd63a2a64ba4037afc7d971b77d0b23a648a6574cdb9464; retrieved 2026-09-16T14:01:46.159Z.