Amateur-built Quickie N23JH accident near Zanesville, Ohio

Probable cause

The failure of the exhaust manifold and a loose mixture screw, which resulted in a partial loss of engine power.

NTSB analysis

The commercial pilot departed in the experimental, amateur-built airplane for a local photography flight. During the return flight, the engine power dropped more than 1,000 rpm, and the engine monitor indicated about twice the normal fuel flow. The pilot was initially able to maintain airspeed and altitude; however, the rpm subsequently began to decrease further, and the pilot determined that the airplane would not be able to reach the airport. During the subsequent forced landing in a cornfield, the airplane's nose struck the ground, and the airplane then nosed over.

Examination of the wreckage revealed a separation of the right exhaust manifold, which was directly beneath the intake breather for the engine. Additionally, a mixture set screw on the carburetor was found loose and extended out, both of which would have resulted in a loss of rpm. Although the weather conditions were conducive to carburetor icing at descent power, the failed exhaust manifold and loose mixture screw likely led to the loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN18LA284 for the full record.