Beech 50 N29Y accident near Sheldon, Missouri

Probable cause

A partial loss of engine power on both engines due to detonation for undetermined reasons.

NTSB analysis

The pilot was returning the multiengine airplane to his home base following an annual inspection other maintenance; the accident flight was the airplane's first flight since the work was performed. After climbing to about 3,000 ft mean sea level (msl), the pilot configured the airplane for cruise flight. The pilot heard the right engine emit "sputtering" noises and backfire. The pilot advanced the throttle of the left engine and then noticed a "large smoke trail" emit from the left engine about 1 minute after the right engine began sputtering. The pilot concluded that the two engines were no longer producing adequate power to remain airborne and performed a forced landing to a tilled dirt field, during which the nose landing gear collapsed, resulting in substantial damage. Signatures consistent with detonation were documented on the left engine Nos. 4 and 6 cylinder assemblies, and the right engine No. 2 cylinder assembly. Oil-covered particles were found in the oil screens from both engines; the source of these particles could not be determined. The reason for the detonation in both engines could not be determined based on the available evidence.

Text from the NTSB. Open the NTSB docket for CEN19LA127 for the full record.