Flight 5452 departed San Juan at 06:20 for a VFR flight to Mayaguez. The flight to Mayaguez was uneventful until the base leg turn to finals for runway 09. Witnesses saw the aircraft making a tight turn (without extending the downwind leg as usual) and overshooting the extended centreline. The aircraft then made a violent turn and entered a high sink rate. The right wingtip struck the ground 643 feet short of the runway threshold and 67 feet right of the extended centreline. The plane continued 100 feet through a chain-link fence and a ditch before pivoting about 180deg coming to rest upright. PROBABLE CAUSE: “Improper maintenance in setting propeller flight idle blade angle and engine fuel flow resulting in a loss of control from an asymmetric power condition. A factor contributing to the accident was the pilot’s unstabilized visual approach.”