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On January 29, 2009, about 1450 eastern standard time, a Cirrus Design Corporation SR22, N224SB, was substantially damaged when it impacted terrain while on final approach to Berkley County Airport (MKS), Monks Corner, South Carolina. The certificated commercial pilot/owner was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the flight, which departed Charleston International Airport (CHS), Charleston, South Carolina about 1440 and was destined for Lake Norman Airpark (14A), Mooresville, North Carolina. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91.
The airplane's Primary Flight Display (PFD) and Multi-Function Display (MFD) were recovered from the wreckage and downloaded in the National Transportation Safety Board (NTSB) Vehicle Recorders Laboratory. Data from the PFD, MFD, along with air traffic control (ATC) radar and voice communication data provided by the Federal Aviation Administration (FAA), showed that the accident airplane departed CHS about 1440, and shortly thereafter began tracking in a northwesterly climb, toward 14A. About 1446, the pilot advised ATC, "I have some fumes in the cockpit, I'm turning around." The pilot then advised the controller that he was going to divert to MKS, and was subsequently issued a frequency change. No further communications were received from the pilot.
About that time, the airplane leveled about 5,800 feet above mean sea level (msl), turned northeasterly toward MKS, and then began a descent. The airplane continued on that track, passing north of MKS, and about 1448 the MFD data ceased recording. About 1449 the airplane reversed course and began heading toward runway 23 at MKS. The airplane's last recorded radar position was observed at 1449:18, at 700 feet msl, about 2 nautical miles northeast of the runway 23 threshold. The PFD also ceased recording position information about this time, though other parameters continued recording until 14:50:15. The final information recorded by the PFD included; 148 feet pressure altitude, 93 knots indicated airspeed, 232-degree heading, and a positive pitch of 0.6 degrees. The final seconds of the accident flight were not recorded by the PFD.
Several witnesses observed the accident airplane as it was on final approach to runway 23. Three of the witness were certificated pilots, and during separate interviews recounted a similar series of events. The witnesses stated that when they initially observed the airplane's approach, it looked "normal". None of the witnesses observed any flames or smoke emanating from the airplane. The airplane cleared the trees and fence prior to the approach end of the runway, but then "pitched [nose] over and went down." They further described that the airplane's attitude was consistent with one normally approaching to land, but the airplane then unexpectedly pitched down into a near 45-degree dive and impacted terrain. One of the witnesses responded immediately to the accident site and noted no fire, smoke, or abnormal fumes.
According to FAA records, the pilot held a commercial pilot certificate with ratings for airplane single engine land and instrument airplane. The pilot possessed 1,164 total hours of flight experience, and his most recent FAA second-class medical certificate was issued on June 5, 2008.
A review of maintenance records revealed the airplane's most recent annual inspection was completed on November 13, 2008. On that date the airplane had accumulated 903 total hours of operation.
On January 7, 2009, the pilot had the airplane serviced by an avionics repair station. According to the entry in the airframe logbook:
"Discrepancy – Pilot reported A/P & Skywatch failed in flight an odor of burnt electronics detected in cabin, A/P and Skywatch functioned fine on subsequent flight after cycling A/P and Skywatch breakers. Preliminary ground check revealed all units functioned properly, found external GPU power plug to be INOP. Removed radios from radio stack, PFD, & MFD checked for any signs of burnt components or malfunction, check satisfactory. Reinstalled units. Removed seats visually checked A/P roll & trim relays below rear seats, no trouble found, reinstalled seats. Gained access behind circuit breaker panel, inspected for loose connections, loose parts, & shorted/chafed wiring. All checked good, closed panel. Removed bolster switch panel, inspect for burnt/chafed wiring or components all checked good, reinstalled bolster switch panel.
Opened empennage close out panel, cleaned connections power and ground connections for aft battery, closed aft close out panel. Removed cowling, opened Master Control Unit, inspected for burnt or damaged components, cleaned all contacts, tightened all connectors and power connect points, re-flowed cold solder joints. Closed and resealed Master Control Unit. External power receptacle functioned normally after cleaning of Master Control Unit. Reinstalled cowling. Ground ran aircraft engine and all aircraft systems and radios for extended time, no trouble found with any systems, no indication of unusual odors in cockpit."
The 1455 reported weather at MKS included clear skies, 10 statute miles visibility, winds from 340 degrees at 3 knots, temperature 12 degrees Celsius (C), dewpoint 7 degrees C, and an altimeter setting of 29.95 inches of mercury.
Berkley County Airport was comprised of a single 4,351-foot-long by 75-foot-wide asphalt runway oriented in a 05/23 configuration. A two-light precision approach path indicator light was located on the left side of runway 23, and projected a 3-degree glide path. The airport was bounded by a perimeter fence, with the northeastern boundary oriented roughly perpendicular to runway 23, and located about 1070 feet from the approach end. The terrain between the airport perimeter fence and the runway 23 threshold was generally flat, with no obstructions present.
WRECKAGE AND IMPACT INFORMATION
The initial impact point was an imprint on the ground consistent with the size and shape of the airplane's wings and three landing gear, and was located about 875 feet from the threshold of runway 23. The airplane's nose landing gear was found at the center of the imprint. The wreckage path was oriented about 210 degrees magnetic, with various pieces of composite structure strewn along it. The next major component found along the path was the propeller, which was located about 35 feet from the initial impact point. The main portion of the wreckage came to rest about 120 feet beyond the initial impact point, and was oriented on a magnetic heading about 138 degrees.
The fuselage was destroyed forward of the forward seats; however, the aft portion of the fuselage remained largely intact. No evidence of an in-flight or post-impact fire was observed. The integrated airframe parachute system was intact, and had not been deployed. The right wing was separated from the fuselage at the aft portion of the wing root, while the left wing remained attached. Control continuity was traced from all flight control surfaces to the central portion of the cabin. Measurement of the flap actuator correlated to a 50-percent flap position.
Both of the battery master switches, as well as their corresponding alternator switches, were found in the "on" position. The avionics switch, which was located immediately to the right of the alternator 2 switch, was in the "off" position. The ice protection, pitot heat, and exterior light switches were all in the "off" position. The fuel selector was positioned to the right fuel tank, and the electric fuel boost pump switch was in the neutral position. The magneto switch was in the "both" position, with the key broken off in the switch tumbler. All of the circuit breakers were in their operative positions, with the exception of the "fuel pump," "turn cord. #2," and the "attitude #2," which were extended and had their crowns broken off. Both the front and rear of the circuit breaker panel were visually examined for evidence of soot, melting, or signatures consistent with overheating, with none noted. All four transient voltage suppressors were removed and visually checked for evidence of failure, overheating, or fire, with none noted.
The PFD, MFD, autopilot, both navigation/communication radios, audio panel, transponder, turn coordinator, enhanced ground proximity warning system, and the master control unit were removed and retained for further examination. Additionally, the Stormscope processor, Skywatch processor, altitude digitizer, bolster panel switches, flap circuit card, and convenience circuit card were removed from the airplane, disassembled (as needed), and visually examined for evidence of overheating, fire, or other damage. None was noted on any of the components. Visual examination of the airplane's wiring also revealed no evidence of any anomalies.
The propeller had separated from the engine aft of the propeller flange, which remained attached to the propeller. All three blades exhibited chordwise scratching, polishing on the forward and aft surfaces, and bending. One blade exhibited leading edge gouging and was missing a portion of the leading edge tip.
The engine was examined at the accident scene, and during a subsequent teardown inspection at the manufacturer's facility. The engine remained largely intact and exhibited varying degrees of impact related damage. The engine crankshaft was rotated by hand, and compression was noted on all cylinders. Continuity of the crankshaft was noted from where the propeller flange separated from the crankshaft, to the rear accessory gears, ignition system, and fuel system components. Rotation of the crankshaft also produced spark at each of the magneto terminal leads. The cabin heater shroud was removed from the exhaust, and exhibited no staining or other evidence of leakage.
The crankshaft propeller flange separated from the assembly and the remained attached to aft portion of the propeller hub. The crankshaft exhibited cracks on the shaft diameter, aft of the propeller flange. The angled cracks observed were consistent with torsional loads on the crankshaft at the time of fracture. Inspection of this engine and testing of its components did not reveal evidence of any abnormalities.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy was performed on the pilot by the Medical University of South Carolina, Department of Pathology and Lab Medicine, Charleston, South Carolina. The autopsy report noted the cause of death as "blunt trauma."
The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing on the pilot. No traces of carbon monoxide, cyanide, or ethanol were detected. Quinine was detected in the blood.
TESTS AND RESEARCH
External and internal examination of the autopilot control head, roll trim motor, MFD, both navigation/communication radios, audio panel, transponder, turn coordinator, enhanced ground proximity warning system, and the master control unit revealed no evidence of any failures, fire, or other thermal distress. The autopilot control head and the roll trim motor were forwarded to their respective manufacturers for examination. The manufacturers' examinations noted no damage, and the units were subsequently subjected to an acceptance test procedures. The autopilot control head and the roll trim motor each performed normally and passed all required tests.
The PFD was disassembled in the NTSB Vehicle Recorders Laboratory and examined. The examination revealed that a single tantalum capacitor was thermally damaged. The capacitor functioned as part of the PFD's +/-15 volt switching power supply circuit. The capacitor was positioned in parallel with an identical capacitor that together reduced switching noise to produce a clean -15 volt output with minimum voltage ripple. The output was used to power the analog PFD signals to the autopilot and the digital PFD signals to the ARINC 429 data bus.
The circuit board containing the damaged tantalum capacitor was subsequently subjected to a partial acceptance test procedure and then installed into a known working PFD for testing. Both tests suggested normal operation of the card, despite the damaged capacitor, and no anomalies were noted during either test.