Air Tractor Inc AT-502 N9185G accident near Carthage, Illinois

Probable cause

The airplane’s inability to climb out of ground effect, which resulted from the pilot using a lower power setting than needed for takeoff due to the mechanic’s installation of the wrong engine torque gauge.

NTSB analysis

The commercial pilot was taking off for an agricultural application flight. The pilot stated that, during the takeoff, the engine did not lose power but that the airplane was unable to gain sufficient speed to climb. After realizing the airplane was not accelerating or climbing as expected, the pilot dumped the chemical load in an attempt to gain altitude. The airplane became airborne and cleared a pond at the end of the airstrip, but it then contacted a dirt bank and nosed over on the far side of the pond.

A postaccident examination of the airplane revealed that the engine torque gauge, which a mechanic had installed in the airplane about 3.5 months before the accident, was for a lower powered engine. The installation of the wrong gauge resulted in the redline on the gauge being lower than it should have been and likely resulted in the pilot not having an accurate torque indication and using a lower power setting than needed for the takeoff.

Text from the NTSB. Open the NTSB docket for CEN14LA349 for the full record.