Flight Details
The helicopter was on a positioning flight after the pilot had completed spraying a field, landed, refueled, and performed a preflight inspection. The pilot then departed to spray another field. While in cruise flight, the helicopter impacted the terrain. The pilot reported no recollection of the accident.
Pilot Account
The pilot stated that during the preceding agricultural flight, there were no changes in the sound of the transmission or any other part of the helicopter.
Transmission Inspection
Post-accident inspection revealed that the transmission had failed in-flight. Three worn and deformed lower pinion roller bearings from the lower planetary gear spider assembly were found loose in the transmission. The inner race for that pinion had missing rollers and was spalled at both the upper and lower rows of its rollers. No spalling was found on the other five inner races from the lower spider assembly, and no abnormal wear was found on rollers from the other pinions.
The helicopter sustained substantial damage.