What happened
The aircraft was engaged in agricultural spraying operations when the pilot detected an abnormal change in engine sound while returning to the home airport. Shortly thereafter, the pilot observed a loss of oil pressure, indicating an imminent mechanical failure. Anticipating that the engine would fail completely, the pilot initiated a forced landing procedure. The pilot selected a portion of an old highway that was clear of motor vehicles as the landing site.
The aircraft touched down and rolled approximately 75 to 100 yards along a steep grade on the roadway. During this roll, the right wing tip struck small gum trees located near the edge of the road. On the opposite bank of the road, there was a dense cluster of plum trees that were somewhat smaller in size. The pilot reported that the aircraft remained precisely on the centerline of the road at approximately 50 mph when it struck these trees. Following the impact with the vegetation, the aircraft swerved to the right and entered a ditch.
The investigation
A post-acc examination of the aircraft revealed the specific mechanical failure responsible for the incident. A flexible oil line was found to have ruptured. This rupture allowed for the loss of engine oil and the subsequent loss of pressure that led to the forced landing.
Findings
The primary factor contributing to the accident was the rupture of a flexible oil line. This mechanical failure resulted in loss of engine oil pressure, necessitating the emergency landing. The pilot's decision to land on an abandoned highway prevented more severe consequences, although the aircraft sustained damage upon striking trees and a ditch.