Air Tractor Inc AT-401 N45297 accident near Toulin, Illinois

Probable cause

A partial loss of engine power as a result of a cracked cylinder and the reduced visibility due to the oil-covered windshield.

NTSB analysis

The pilot reported that he had made his last agricultural spray run. The airplane was about 200 feet above ground level when one of the engine's cylinders cracked resulting in oil covering the windshield. The pilot flew to a satellite airstrip about 5 miles away. The pilot reported that the airstrip was short and his visibility was reduced due to the oil-covered windshield. The airplane overran the runway and nosed over when it collided with a ditch. A postaccident inspection of the airplane revealed that the number two cylinder of the engine had a crack located near the front spark plug and stretching to the rear spark plug. The Federal Aviation Administration had previously issued an Airworthiness Directive (AD) addressing the accident engine model. The AD required initial and repetitive visual and florescent penetration inspections of cylinders for cracking. This document was prompted by reports of cylinder head cracking which can result in the loss of engine power. The airplane’s logbooks indicated that 18 hours of time in service had elapsed since the last visual inspection of the cylinder per the AD requirements.

Text from the NTSB. Open the NTSB docket for CEN10LA420 for the full record.