Diamond DA20 N653DC accident near Mountain Rest, South Carolina

Probable cause

A partial loss of engine power due to multiple discrepancies of the engine's ignition system.

NTSB analysis

According to the pilot, the airplane was in cruise flight about 6,500 ft mean sea level when the engine lost partial power. The pilot stated that he selected a field for a forced landing because no airport was within gliding distance. During the descent, the pilot's remedial actions to restore engine power were unsuccessful, so he declared an emergency over the radio and secured the engine before the off-airport landing. The airframe sustained substantial damage to the wings, fuselage, and empennage during the landing.

After the accident, several engine starts were attempted on the airframe, but each was unsuccessful. The engine was removed and shipped to the manufacturer, where an engine start was attempted in a test cell. The engine ran roughly and would not run continuously. Troubleshooting was performed, and internal engine timing and ignition timing were confirmed. Ultimately, both magnetos and both ignition harnesses required replacement to achieve a successful engine run. Disassembly of the right magneto revealed excessive wear, which rendered it inoperative. The left magneto required cleaning of the points to operate, and both ignition harnesses displayed damage due to overtightening of restraint clamps, which resulted in ignition "leaks" and intermittent spark at the spark plugs. It is likely that the combination of all of the discrepancies of the ignition system ultimately resulted in the engine's partial loss of power during the accident flight.

Text from the NTSB. Open the NTSB docket for ERA19LA029 for the full record.