# Accident 20170706010589A: Bell 47D1, Big Lake, MN, July 6, 2017

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: July 6, 2017, 16:50 local time
- Place: Big Lake, MN
- Damage: Substantial damage
- Phase of flight: Takeoff: Departure Roll
- Operating rules: Agricultural (Part 137)
- Operator: 6SQG
- Location: 45.3133° N, 93.7175° W: From the FAA
- Nearby events: https://openairdocs.org/map.md?lat=45.3133&lon=-93.7175&mi=10
- Aircraft: N153B, registered now (https://openairdocs.org/aircraft/N153B) (OpenAirDocs)
- Registry model: Bell 47D1 (registry code 1180802, https://openairdocs.org/model/bell-47d1) (OpenAirDocs)
- Registry engine: Franklin 6V4 series (registry code 27033, https://openairdocs.org/engine/franklin-6v4-series) (OpenAirDocs)
- Reported make and model: BELL 47D1
- Reported engine: LYCOMING VO-435-A1F
- People aboard: 1
- Fatal injuries: 0
- Other injuries: 0
- Pilot certificates: Airline transport
- Pilot flight hours: 16,300 total, 20 in this make and model, 20 in the last 90 days
- NTSB investigation: [NTSB CEN17LA264](https://openairdocs.org/ntsb/CEN17LA264) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/20170706010589A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

THE PILOT WAS PERFORMING AGRICULTURE SPRAY OPERATIONS AND HAD JUST COMPLETED A REFILL OPERATION OF PESTIDICES.  AFTER INCREASING ENGINE RPM TO 3,100 RPM AND STARTED TO ADD COLLECTIVE, PILOT FELT A SUDDEN PULL AND HEARD LOUD SNAP.  WHEN HE LOOKED AROUND TO DETERMINE WHAT HAPPENED, HE SAW THAT THE LOADING TRUCK HAD SIGNIFICANT DAMAGE.  THE PILOT STATED THAT HE REALIZED THE ENGINE WAS STILL RUNNING AND SHUT IT OFF.   THE PILOT DEPARTED THE AIRCRAFT WITH NO INJURIES.  THE ROTOR MAST HAD DEPARTED THE AIRCRAFT AND WAS FOUND TO THE 8'OCLOCK POSITION.

## The NTSB's investigation of this event (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB CEN17LA264](https://openairdocs.org/ntsb/CEN17LA264), Jul 6, 2017: Bell 47D1 (N153B), Big Lake, MN, substantial damage. Probable cause: The failure of the metal core assembly within a wooden main rotor blade due to undetected corrosion and fatigue, which caused the wooden blade to separate from the rotor mast.

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

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