Hiller UH-12E N236HA accident near Colusa, California

Probable cause

The pilot's failure to maintain an adequate airspeed and an inadvertent encounter with settling with power while flying downwind.

NTSB analysis

The pilot reported that he and the owner of the helicopter were flying a reconnaissance flight in preparation for a possible frost control flight the following morning. They were attempting to identify potential obstacles in the area. As they were flying slowly over the north edge of an almond orchard he initiated a descent, and slowed the helicopter to just above effective translational lift. He turned southbound and noted a 7- to 10-mile-per-hour tailwind. He reported that the tailwind, coupled with the descent, caused the helicopter to enter a settling with power condition. He stated that due to the close proximity of the trees he was not able to perform a normal recovery of lowering the collective and applying forward cyclic control. The helicopter descended between a row of trees and the main rotor blades struck the trees. The pilot stated that there were no mechanical malfunctions with the helicopter before the accident.

Text from the NTSB. Open the NTSB docket for WPR11CA146 for the full record.