N96671

The helicopter pilot reported that, during an aerial application flight with an easterly heading, about 3 feet above ground level, the "wind suddenly shifted, a gust of wind [came] from the west" and the helicopter "settled." The pilot increased power and raised the collective but the helicopter impacted the terrain.

The helicopter sustained substantial damage to the fuselage and tail boom.

The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.

The pilot further reported that the helicopter was equipped with a muffler, which he believed adversely affected engine's performance. Correspondence with the certificate holder of the helicopter, "determined to be no reduction of horsepower with the muffler installed if done as per the instructions per the STC."

The automated weather observation station located 5 NM east of the accident, reported that, about 8 minutes before the accident, the wind was from 180° at 16 knots, gusting to 25 knots. The same automated station reported that, about 32 minutes after the accident, the wind was from 180° at 16 knots, gusting to 26 knots.