Diamond Aircraft Ind Inc DA 40 NG N471BL accident near Smithfield, North Carolina

Probable cause

Maintenance personnel’s failure to set the correct engine timing after the replacement of a cylinder head and exhaust camshaft before the accident flight, which resulted in a total loss of engine power.

NTSB analysis

According to the flight instructor, shortly after takeoff, she heard a “weird” noise coming from the engine and noted a drop in engine rpm. The flight instructor directed the pilot receiving instruction to turn back toward the airport; however, the engine lost all power, and the airplane impacted trees about 1 mile from the departure end of the runway. The airplane sustained substantial damage to the wings, fuselage, and empennage.

A postaccident examination of the engine revealed that the engine valvetrain was not timed correctly and that the misalignment resulted in a piston striking a valve. The valve head had separated and fallen into the cylinder, resulting in the total loss of engine power. Examination of the maintenance logbooks revealed that the cylinder head and exhaust camshaft had been replaced the day before the accident flight. Thus, it is likely that the engine’s timing was not set correctly after this maintenance.

Text from the NTSB. Open the NTSB docket for ERA22LA169 for the full record.