History of Flight
On August 14, 2016, at about 1115 central daylight time, a Piper PA-31-325, registration N447SA, was substantially damaged when it impacted terrain near Northport, Alabama, while diverting to Tuscaloosa Regional Airport (TCL). The private pilot and five passengers sustained fatal injuries. The airplane was owned by Oxford University Aircraft Charters, LLC and operated by the pilot under Part 91. Day visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the personal flight, which departed Kissimmee Gateway Airport (ISM), Florida, about 0855 with an intended destination of Oxford University Airport (UOX), Mississippi.
Before departure, the airplane's fuel tanks were topped off with 134 gallons of fuel. The pilot reported on the flight plan that the airplane had about 5 hours 10 minutes of fuel on board. At 0915, the airplane leveled off at 12,000 ft mean sea level. At 1059, the pilot reported a failure of the right engine fuel pump and requested a diversion to the nearest airport. The controller provided radar vectors toward runway 30 at TCL. When about 13 miles from TCL, the pilot reported that the airplane lost both fuel pumps and had no power. The airplane continued to descend on an extended final approach until it impacted trees about 1,650 ft short of the runway threshold.
Pilot Information
The pilot held a private pilot certificate with ratings for airplane single- and multi-engine land and instrument airplane. His most recent FAA third-class medical certificate was issued in August 2014. According to a flight log, he had accumulated 48.7 hours of flight experience in the accident airplane since March 2016. His logbook noted 2.9 hours of dual flight instruction during two flights on March 17, 2016. The flight instructor who flew with him stated that he did not provide any multi-engine training, and the pilot had not received any training in the accident airplane. The instructor did not practice single-engine operations or emergency procedures with the pilot in that airplane.
Aircraft Information
The airplane was manufactured in 1984 and purchased by the pilot through a limited-liability company on March 14, 2016. It was equipped with two Lycoming TIO-540-series engines, each driving a 4-bladed Hartzell controllable pitch propeller. The most recent annual inspection was performed on November 13, 2015, at 3,260.8 total hours in service.
According to a flight log squawk list, the right engine fuel boost pump light had illuminated several times in the month before the accident. The right engine fuel pump was reported as intermittent, the right fuel pressure gauge was oscillating, and the right engine did not want to run without the boost pump. The fuel boost pump annunciator light illuminated and was tested on June 25, 2016, with fuel pressure and flow within limits. On July 19, 2016, about 17 hours before the accident, the right engine-driven fuel pump and right engine boost pump were replaced. After replacement, neither the pilot nor the flight instructor experienced further issues. The pilot noted on August 10 that "everything was fine, but the screen on the EDM was going out." On the day of the accident, an entry noted the right engine cylinder No. 1 was "hot on climb" and "ran rich of peak = 31", 2200, 23 gal/side, and EDM screen flicker.
The fuel system consisted of four fuel tanks (two per wing) with total capacity 192 gallons (183.4 usable). Under normal operation, fuel was routed from cells through the selector valve and filter to the fuel boost pump, then through the emergency pump, firewall shutoff, engine-driven pump, fuel injector, and cylinders. Emergency fuel pumps provided pressure if engine-driven pumps failed. Fuel boost pumps operated continuously with circuit breakers and warning lights.
Meteorological Information
The 1121 weather observation at TCL included wind from 170° at 10 knots gusting to 14 knots, visibility 10 miles, scattered clouds at 2,600 ft, broken clouds at 3,600 ft, temperature 30°C, dew point 25°C, and altimeter setting 30.09 inches of mercury.
Wreckage and Impact Information
The airplane impacted trees and ground, coming to rest upright on a magnetic heading of 011°. The debris path was about 250 ft long on a 300° heading. A postimpact fire ensued and was extinguished by first responders. The forward fuselage was separated and heavily damaged. Control continuity was confirmed to the cockpit. Throttle, mixture, and propeller levers were full forward. Left and right fuel selector levers were in the outboard tank positions. Fuel shutoff valves were ON, crossfeed OFF. Right engine alternate air was ON, left OFF. Flap lever was retracted. The Hobbs meter indicated 1450.4 hours. All circuit breakers except flap control and compass were in place.
Both wings were fragmented; fuel tanks were breached. The left inboard tank contained an unmeasured amount of fuel. The right propeller was unfeathered; two blades bent aft, two straight. Thumb compression and suction were observed on most right engine cylinders. The left propeller also unfeathered with two blades bent aft. Compression and suction were observed on all left engine cylinders.
Tests and Research
Examination of the right engine-driven fuel pump showed corrosion but no anomalies preventing operation. The left engine-driven fuel pump had low outlet pressure on test but passed after adjustment. The right emergency fuel pump showed corrosion and seized vanes, attributed to postimpact fire damage. The left emergency fuel pump operated normally. The right fuel boost pump exhibited thermal damage, corrosion, and fractured magnets; the left boost pump operated normally.
The engine data monitor recorded the entire flight. Right engine fuel flow became erratic around 1105, increasing to about 110 gallons per hour, then decreasing. Right engine temperatures decreased afterward. Left engine fuel flow became erratic around 1113, increasing to over 90 gallons per hour, then decreasing. Left engine temperatures also decreased.
Fuel endurance calculations based on the pilot's noted consumption of 23 gallons per hour per engine indicated that the outboard fuel tanks provided about 1 hour 45 minutes of fuel.