Cessna 172C N8856B accident near Algona, Iowa

Probable cause

The No. 1 cylinder head separating at the cylinder head-to-barrel interface and the subsequent total loss of engine power.

NTSB analysis

After takeoff for an instructional flight, when the airplane reached 1,800 ft mean sea level, the student pilot began a left turn toward the destination. Shortly after, the engine went silent and stopped producing power. The flight instructor took control, slowed the airplane, and landed into the wind on a gravel road. During the landing roll, the left wheel caught the edge of the road, and the airplane veered into a ditch, which resulted in substantial damage to the wing and fuselage.

Examination of the airplane revealed that the engine's No. 1 cylinder head had separated at the cylinder head-to-barrel interface. The engine had accumulated 605.9 hours since the last engine overhaul, which was conducted over 23 years before the accident. The engine manufacturer's recommended time between overhaul for the accident engine was 1,800 hours or 12 years. However, it could not be determined if the lack of an overhaul within the manufacturer's recommended overhaul period led to the No. 1 cylinder head separating at the cylinder head-to-barrel interface.

Text from the NTSB. Open the NTSB docket for CEN18LA051 for the full record.