Accident Overview
On August 12, 2015, at approximately 1600 central daylight time, a Grumman G-164B agricultural airplane, registration N311AL, lost engine power shortly after takeoff near Sac City, Iowa. The pilot was not injured, and the airplane sustained substantial damage during the subsequent forced landing. The aircraft was registered to and operated by a private individual under 14 Code of Federal Regulations Part 137 as an agricultural flight. Visual meteorological conditions prevailed at the time of the accident.
Pilot Report
According to the pilot, he had changed the engine oil the night before the flight and completed a 45-minute engine run. On the day of the accident, he performed a normal run-up, during which everything appeared normal. He noted a 50 rpm drop per magneto during the engine run-up. He then departed down the runway, lifted the tail at 60 mph, and accelerated to 80 mph. Shortly after becoming airborne, he felt the airplane was not performing as expected. The airplane was able to climb over a set of wires, but the engine power faded. The pilot advanced the engine controls full forward and selected a cornfield for the forced landing. During the landing, the airplane nosed over and came to rest inverted.
Investigation Notes
Due to the unharvested cornfield, the airplane remained at the site until approximately November 7, and an engine examination was not performed. The pilot stated that he believed the engine's blower or supercharger had failed, because the engine did not stop but seemed to lose power. A completed NTSB Form 6120 was not returned by the operator.