Probable cause
The in-flight failure of the main rotor mast hub due to several undetected fatigue fractures.
NTSB analysis
While the pilot was conducting an aerial application flight, he felt a small jolt, the main rotor mast failed, and the helicopter collided with terrain.
Four days before the accident, a mechanic performed a dye penetrant inspection on the rotor mast; the helicopter had only flown 9 hours since the inspection.
Attempts to retrieve the rotor mast parts from the operator were unsuccessful and when contact was reestablished with the owner, he had already disposed of the parts. Photos of the broken rotor hub were reviewed by the National Transportation Safety Board (NTSB) Materials Laboratory, which determined that several preexisting, progressive cracks were present.
Text from the NTSB. Open the NTSB docket for CEN22LA318 for the full record.
Event
- Date
- Jul 6, 2022
- Type
- Accident
- Place
- Becker, Minnesota
- Highest injury
- Serious
- Serious injuries
- 1
- Weather
- Visual (VMC)
- Light
- Day
Hiller UH12E
- N-number
- N64272
- Category
- Helicopter
- Year built
- 1965
- Damage
- Substantial
- Operating rule
- Part 137 (agricultural)
- Purpose of flight
- Aerial application
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.