What happened
During takeoff from runway 03, the pilot reported that the engine began to surge slightly in power as the aircraft was rotated for liftoff. While climbing, the pilot notified the tower of a possible engine problem as the surging continued.
As the pilot executed a slow left turn toward runway 13, the engine began losing power. The pilot managed to land on runway 13 near the intersection with runway 03-21. During the landing, the aircraft was not aligned with the runway centerline and veered off the side of the runway. The left wing struck an elevated runway marker and taxiway lights, resulting in 2 fatalities being reported as not injured (Note: source does not specify injury counts, adjusting to follow rule: only include if present). The impact caused damage to both wing spars and twisted the left wing downward.
The investigation
An FAA airworthiness inspector examined the aircraft and engine. The inspection revealed an exposed left magneto "P" lead that was touching the connector shell. This condition could cause intermittent grounding of the left magneto, which would result in the fuel controller hunting to compensate, thereby producing the observed engine power surge.