CEN14FA438

The pilot’s incapacitation in flight as the result of a an acute cardiac event, which resulted in a loss of control and collision with terrain.

The multi-engine airplane was about 500 ft above ground level (agl) and on a left base landing approach when a witness saw the airplane suddenly point straight down, begin spinning, and make three complete rotations before impacting terrain in a partially nose-down attitude. The airplane came to rest upright, and was mostly consumed by an immediate postimpact fire. A postaccident examination of the wreckage revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. A pilot operating another pipeline patrol airplane in the vicinity reported frequent severe-to-extreme turbulence about 1,000-2,000 ft above ground level. Data from an on-board GPS unit indicated that, while on the base leg of the airport traffic pattern for landing, the accident airplane's airspeed decayed 10 knots below the manufacturer's recommended approach speed for turbulent conditions. An autopsy performed on the pilot found significant existing atherosclerotic disease (60 to 80 percent) and described evidence of an acute, premortem, nonocclusive thrombosis of the left anterior descending coronary artery. The medical examiner's conclusion stated it "appears the decedent likely suffered an acute cardiac event while piloting his aircraft" and "died primarily due to hypertensive and atherosclerotic cardiovascular disease and that his multiple blunt force injuries likely contributed to his death." It is likely that the pilot was incapacitated due to the acute cardiac event and lost control of the airplane during the approach to land.

There was no record of any radio communications with N127BC. The Unicom radio frequency at 0F3 was not recorded. The FAA Airport/Facility Directory, South Central U. S., indicated that 0F2 was a non-towered airport with a field elevation of 1,100 feet msl. The only runway was 17-35, which was an asphalt runway 3,603 feet long by 60 feet wide. Runway 17 was oriented to 174 degrees true and 167 degrees magnetic. The wreckage was moved to another location and examined. Left engine The engine exhibited impact damage and thermal damage from the postimpact fire. The induction filter was crushed and fire damaged. Numerous components of the induction system were destroyed by the postimpact fire. The throttle valve was observed in the idle (closed) position. The left magneto mounting flange was fractured and the magneto was separated from the topside of the engine. The ignition harness remained attached to the magneto. Both magnetos were examined. The sparkplug electrodes displayed a normal wear pattern and little-to-no combustion deposits when compared to the Champion Aviation Service Manual (AV6-R). The fuel pump flange was fractured and the fuel pump was displaced downward on the backside of the engine. The pump sustained impact and thermal damage. The aneroid bellows were separated from the pump and the valve shaft sustained deformation damage. The drive coupling was fractured with the fracture surface being deformed to one side. The throttle body sustained fire damage that resulted in the separation of the metering unit from the body. The metering unit sustained thermal and deformation damage to the levers and shafts. The fuel inlet screen was removed and found to be free from any obstructions. The fuel manifold remained secured to the topside of the engine and the cap was safety-wired to the housing. The fuel injector lines remained attached to the manifold valve. Disassembly of the fuel manifold valve revealed that the screen was clear, the diaphragm was in place, intact, and pliable, and the plunger was attached. All of the injector nozzles were clear and free from obstructions. The upper deck reference line remained secured around the nozzles. The O-rings were in place and no anomalies were noted. The oil sump was flattened and displaced up into the bottom of the engine. The oil sump was punctured. The oil and scavenge pumps contained residual oil. No anomalies were noted with the pump gears. The oil pump housing displayed some circular scoring on the cap and a half-inch score mark on the housing wall. The oil pump housing contained charred oil that flaked off when touched. The oil filter was examined. The cylinders were bore scoped during the on-scene portion of the examination with no anomalies noted. During the teardown examination the cylinders were removed and the cylinder barrels, cylinder heads, valves and valve seats were examined. The cylinder heads and valves displayed normal combustion deposits. The rocker arms and shaft were examined. The pistons were intact with normal combustion deposits noted on the piston faces. The piston pins were intact and showed no signs of operational distress. All of the piston rings were intact and lubricated. The engine case halves were separated and inspected. The crankshaft, bearings, connecting rods, counterweights, camshafts and camshaft lobes were examined. The lifters, accessory gears, starter, starter adaptor, alternator, and propeller governor were examined. The turbocharger, turbo controller, waste gate, and overboost valve were examined. Right engine The engine exhibited impact damage and thermal damage from the postimpact fire. The induction filter was crushed. Numerous components of the induction system were destroyed by the postimpact fire. The throttle valve was observed in the idle (closed) position. Both magnetos were examined. The sparkplug electrodes displayed a normal wear pattern and little-to-no combustion deposits when compared to the Champion Aviation Service Manual (AV6-R). The fuel pump remained secured to the backside of the engine, but sustained thermal damage that destroyed the aneroid housing and distorted much of the fuel pump housing. The drive coupling remained intact but was bent. The coupling insert area of the drive shaft was displaced. The metering unit sustained thermal and deformation damage to the levers and shafts. The fuel inlet fitting was destroyed. The inlet screen was examined and the soldered joints for the screen were melted away. The screen was covered in soot and re-solidified molten metal. The fuel manifold remained secured to the topside of the engine and the cap was safety-wired to the housing. The fuel injector lines remained attached to the manifold valve. Disassembly of the fuel manifold valve revealed that the screen was clear, the diaphragm was in place, intact, and pliable, and the plunger was attached. All of the injector nozzles were clear and free from obstructions. The upper deck reference line remained secured around the nozzles. The O-rings were in place and no anomalies were noted. The oil sump and oil filter were examined. The cylinders were bore scoped during the on-scene portion of the examination with no anomalies noted. During the teardown examination the cylinders were removed and the cylinder barrels, cylinder heads, valves and valve seats were examined. The cylinder heads and valves displayed normal combustion deposits. The rocker arms and shaft were examined. The pistons were intact with normal combustion deposits noted on the piston faces. The piston pins were intact and showed no signs of operational distress. All of the piston rings were intact and lubricated. The engine case halves were separated and inspected. The crankshaft, bearings, connecting rods, counterweights, camshafts and camshaft lobes were examined. The lifters, accessory gears, starter, starter adaptor, alternator, and propeller governor were examined. The turbocharger, turbo controller, waste gate, and overboost valve were examined. Propellers Both propellers had impact damage consistent with a low amount of rotational energy absorption. Although there was evidence of rotation at impact, with low engine power during the impact, the exact engine power levels could not be determined. Neither propeller had indications consistent with high power at impact. Neither propeller had impact signature markings or component positions indicating the blades had been in the feathered blade angle range. Both propellers had several indications of operating near the low pitch to latch angle position at the time of impact. Neither propeller had evidence of damage to the latch arrowheads or the latch mechanism that would indicate latch engagement during at the time of impact. There was no evidence of any type of fatigue failure. Blades on both propellers had blade bending, twisting, and overall propeller assembly damage typical of low engine power at impact. The examination of the entire wreckage revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. Electronic Devices A Garmin GPSmap 696 handheld GPS device was removed from the wreckage and sent to the NTSB vehicle recorder laboratory in Washington, D.C. Data was successfully extracted from the GPSmap 696 and included 81 sessions from September 10, 2013, through August 15, 2014. The accident flight was identified and consisted of 878 data points starting from 1333:57 and ending at 1535:26 on August 15, 2014. Data showed that, as the airplane neared 0F2, the northbound airplane began to descend about 1534:16 and turned left to enter a left base turn to land on runway 17 at 0F2. During the descent, the airplane's groundspeed gradually decreased. The aircraft's GPS altitude and groundspeed decreased from a GPS altitude of 2,249 feet msl and 132 knots at 1534:16 to its final recorded value of 1,528 feet msl and 8