Piper PA32RT N39686 accident near Camden, South Carolina

Probable cause

A total loss of engine power due to the improper torqueing of the magneto, which led it to its malfunctioning in flight.

NTSB analysis

The airline transport pilot and passenger were breaking in the newly overhauled engine on a cross-country flight in accordance with the engine manufacturer's break-in procedures. About 20 minutes after departure, during cruise flight at 75% power, the engine began running "mildly rough" and then began "cutting in and out." The pilot chose to divert to another airport, and about 5 miles from that airport, the engine experienced a total loss of power. The pilot subsequently performed a forced landing to a field, during which the wings and fuselage sustained substantial damage.

When the single-drive dual magneto was placed on a test stand, the left side of the magneto did not produce spark. Internal examination of the magneto revealed that the left and right capacitor fastenings were not properly torqued, which resulted in intermittent arcing and melting of the cam follower and the subsequent loss of power. It could not be determined when the magneto's capacitor fasteners had last been torqued.

Text from the NTSB. Open the NTSB docket for ERA16LA331 for the full record.