N3633Q

On May 13, 2007, about 1630 Pacific daylight time, a Schweizer G-164B, N3633Q, struck wires and collided with terrain near Colusa, California. Martin's Dusters, Inc., was operating the airplane on an aerial application mission under the provisions of 14 Code of Federal Regulations (CFR) Part 137. Visual meteorological conditions prevailed, and no flight plan had been filed. The commercial pilot was killed; the airplane was destroyed. The local flight departed Colusa County Airport about 1600.

According to the operator, he briefed the pilot on the morning of the accident about the field that was scheduled for an application of rice seed. The operator stated that the pilot was to fly over the top of the wires; the operator's policy was to fly above the wires. Approximately midday, the operator was assigned the field to drop seed, and assigned the pilot to do the drop.

An agricultural commercial pilot witness reported that he observed the airplane making the application to the field under the wires. On the second pass, the airplane's vertical stabilizer and rudder struck the wires. The rudder then separated from the airplane. The airplane pitched nose up, stalled, spun approximately three times, and impacted terrain. The airplane was destroyed by post-impact fire.

The operator reported that the pilot, age 50, had accumulated approximately 6,400 total flight hours and 450 in the accident airplane make and model.

The National Transportation Safety Board investigator-in-charge (IIC) examined the wreckage at Plain Parts, Pleasant Grove, California. The control system exhibited multiple disconnects. The fracture surfaces were angular, and several control rods were bent. The crankshaft fractured and separated between the front of the crankcase and the propeller flange. The fracture surface was angular to the longitudinal axis and exhibited a shear lip. The propeller blades had leading edge gouges and trailing edge buckling. The blade tips twisted toward the low pitch, high revolution per minute (rpm) position. One blade tip separated along a plane angular to the span; another blade partially separated along a plane angular to the span.