Accident Overview
On September 30, 2016, at about 1730 eastern daylight time, a Piper PA-32, registration N39686, experienced a total loss of engine power during a personal flight, resulting in a forced landing in a field. The airplane was substantially damaged, and the right wing separated from the main spar at the wing root. The pilot and passenger sustained minor injuries. The flight originated from Florence Regional Airport (FLO), Florence, South Carolina, and was destined for Asheville Regional Airport (AVL), Asheville, North Carolina, under an instrument flight plan. Visual meteorological conditions prevailed.
Pilot and Aircraft Information
The pilot held an airline transport pilot certificate with ratings for airplane single-engine land, multi-engine land, and instrument airplane, as well as a flight instructor certificate. He also held a second-class medical certificate and reported 7,200 total hours of flying experience.
The six-seat, low-wing, retractable tricycle landing gear-equipped airplane was manufactured in 1978. It was powered by a Lycoming TIO-540, 300-horsepower engine driving a McCauley two-blade, constant-speed propeller.
Pre-Accident Engine History
The engine had recently been overhauled and reinstalled. On September 26, the pilot conducted a test flight during which he noted high No. 5 cylinder head temperature and light smoke coming from the engine. The No. 5 cylinder head temperature probe was replaced before the subsequent flight.
Accident Sequence
The purpose of the accident flight was to break in the engine according to the manufacturer's published procedures. After departing FLO, the airplane climbed to 8,000 feet mean sea level. Approximately 20 minutes after departure, while in level flight at 75% power, the engine began running "mildly rough." The pilot descended to a lower altitude and planned to return to FLO. The engine then began "cutting in and out," prompting the pilot to declare an emergency and attempt to land at Woodward Field Airport (CDN) in Camden, South Carolina. About 5 miles from CDN, the engine lost all power, and the pilot performed a forced landing in a field.
Post-Accident Examination
Examination of the airframe revealed substantial damage to the wings and fuselage. The propeller blades were bent aft. Engine control continuity was confirmed from the cockpit to the respective components. When manually rotated, thumb compression was obtained on all cylinders. Fuel lines were secure, and no staining was observed. The fuel screen and fuel drained from the throttle body were free of debris.
Examination of the single-drive dual magneto showed that the left side did not produce spark when tested on a stand. The right side initially produced spark on only four of the six leads when rotated by hand, but on the test stand it produced spark on all leads. Internal inspection revealed that the left-side cam follower was melted, which prevented opening of the points. The left and right capacitor fastenings were not properly torqued: the left nut was loosened by hand, and the right nut was loosened easily with a wrench and removed by hand. The cam follower also exhibited melting and signatures of intermittent arcing, consistent with the inadequate torque observed on the capacitor fastenings.
Weather Information
The closest weather reporting facility was Woodward Field Airport (CDN), about 5 miles west of the accident site. At 1725, the reported conditions included wind from 220° at 5 knots, visibility 10 statute miles, clear sky, temperature 27°C, dew point 13°C, and barometric altimeter setting of 29.96 inHg.
Probable Cause
The probable cause of the accident was the inadequate torque on the magneto capacitor fastenings, which led to arcing and melting of the cam follower, resulting in a loss of spark from the magneto and subsequent total loss of engine power.