Bell 206B accident near El Centro, California, December 24, 2023

The NTSB's narrative final · quoted from the NTSB record

The pilot was flying in night visual flight rules (VFR) conditions about 100 ft above ground level (agl), toward an intended application site for agricultural pesticides, when the helicopter began to make a loud noise and vibrate. Unsure if the helicopter had lost rotor rpm or not, the pilot lowered the collective and initiated a run-on landing to a field. Postaccident examination of the helicopter’s airframe and engine revealed that the forward-most flex plate of the forward flex coupling on the KAflex driveshaft assembly was fractured. No evidence of additional preaccident mechanical malfunction or failure that would have precluded normal operation was observed. Fracture analysis revealed that the flex plate failed due to a fatigue fracture resulting from a loose attachment between the flex plate and the forward driveshaft fitting. Multiple areas of missing or replacement torque paint were observed throughout the KAflex driveshaft assembly’s joints. It is likely that the joints had either slipped or been manually disturbed before the non-original torque paint was applied, which would have been cause for the driveshaft assembly to be removed and shipped to the manufacturer. However, no evidence of the driveshaft’s removal after visual confirmation of joint slippage or disturbance was recorded in the aircraft maintenance logs.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.

Other NTSB records under N111PM the same tail number, which may have belonged to a different aircraft at the time