History of Flight
On August 20, 2008, at 1800 Pacific daylight time, a single-engine SOCATA RALLYE 235E, registration N711BZ, collided with a California Highway Patrol (CHP) weigh station building near South County Airport of Santa Clara County (E16), San Martin, California. The airplane was operated by Silicon Rallye, Inc. under 14 Code of Federal Regulations Part 91. The private pilot/owner, the sole occupant, was killed. The airplane was destroyed in the post-impact fire; there were no ground injuries. The airplane departed about 1755 for pattern work.
Several witnesses on both the north and southbound lanes of nearby highway 101 reported no smoke or fluid emanating from the airplane, but observed it "undulating" up and down and flying at a low altitude before the left wing came up and the airplane turned sharply to the right.
An airborne helicopter pilot landing at South County airport reported hearing the accident pilot transmit a radio call on takeoff. A short time later, he heard the accident pilot radio that he was on the base leg. The pilot witness saw the airplane at that point and continued his landing on the parallel taxiway. He heard the accident pilot call 'final' and expected to see the airplane on roll-out to his right. Looking to the right, he did not see the airplane. When he looked back, he saw smoke coming from the weigh station. The pilot stated that he did not hear any "stress or distress" in the accident pilot's voice during his transmissions.
A co-owner in the accident airplane reported no history of mechanical problems. For the past five years, the airplane had been kept at Reid-Hillview airport, and was at South County Airport for cosmetic repairs (paint touch-up). On the day of the accident, they arrived at the airport and performed a 45-minute pre-flight inspection, including checking flight controls and fuel for contamination. The owner reported sufficient fuel on board. The accident pilot attempted to start the airplane; they eventually had to jump start the battery. Prior to departure, the accident pilot stated he would perform two touch-and-go takeoffs and landings, then fly to Reid-Hillview airport.
The co-owner watched as the airplane taxied to the run-up area, where it performed a run-up with no discrepancies. After takeoff, the airplane circled over the airport; on final approach, the airplane appeared "rock-solid, stable approach." The co-owner reported that a helicopter was about 150 to 200 feet ahead and to the left of the accident airplane when the left wing of the accident airplane came up and the airplane "dove into the scale facility." The co-owner stated that the airplane had plenty of power and there was nothing unusual other than the sharp right-hand banking turn.
Personnel Information
A review of Federal Aviation Administration (FAA) airman records revealed that the 60-year-old pilot held a private pilot certificate with airplane single-engine and instrument airplane ratings. The pilot held a third-class medical certificate issued on October 18, 2007, with the limitation that corrective lenses must be worn for near and distant vision. At that time, the pilot reported 1,000 hours total flight time on the medical application. No other personal flight records were located.
Aircraft Information
The airplane was a 1977 SOCATA Rallye 235E, serial number 12936. A review of the logbook revealed a total airframe time of 1,580.0 hours at the last annual inspection on March 3, 2008, performed by Magnum Aviation in San Martin. A work order from Magnum Aviation dated June 24, 2008, identified three corrective actions, including touch-up paint. A Textron Lycoming O-540-B4B5 engine, serial number L18598-40A, was installed. Total time recorded on the engine at the last 100-hour inspection on March 3, 2008, was 1,580.0 hours, with 482.89 hours since major overhaul.
Wreckage and Impact Information
According to the California Highway Patrol, the airplane came to rest in an easterly direction after impacting the west-facing wall of the Northbound Gilroy Inspection Facility weigh station. The propeller assembly, engine, and forward portion of the cockpit were destroyed in the post-impact fire. Both wings separated from the airplane and sustained fire damage along with the tail section.
Medical and Pathological Information
On August 25, 2008, the Santa Clara County Medical Examiner completed an autopsy on the pilot. The autopsy report noted the presence of marked coronary artery disease, with a "pinpoint lumen" of the proximal right coronary artery and the proximal left anterior descending coronary artery. The report also noted moderate atherosclerosis of the aorta and cholesterolosis of the gallbladder. No other pre-existing disease was indicated.
The FAA Forensic Toxicology Research Team performed toxicological testing. The report noted only Losartan detected in the blood and urine.
A review of the pilot's FAA airman medical records indicated a history of diabetes (well-controlled on metformin), high blood pressure (well-controlled on nifedipine, lisinopril, and losartan), gout (well-controlled on allopurinol), and high cholesterol (treated with atorvastatin). The pilot's height was noted as 67 inches and weight as 236 pounds on the most recent medical application. The records do not indicate any history of heart disease, and there is no record of screening tests for such disease other than cholesterol testing in 1999.
Tests and Research
The airframe and engine were examined at Plain Parts, Pleasant Grove, California, on November 25, 2008. No mechanical anomalies were identified. The airframe was mostly consumed in the post-impact fire. Investigators were unable to establish flight control continuity due to thermal destruction. Rudder and horizontal stabilizer cables and associated hardware were identified in what remained of the tail section; the cable ends were splayed and broomstrawed. Flight control cables in the wings also displayed broomstrawing at the ends. The airplane manufacturer identified the seat rails for the two front seats and noted no discrepancies.
Investigators placed the engine on a hoist for inspection. Visual examination revealed extensive thermal damage, precluding rotation. The engine was borescoped with no evidence of foreign ingestion. No evidence of heat distress or lubrication deprivation was noted on connecting rods, crankshaft, and cam lobes. The accessory case was removed; accessory gears, including the crankshaft gear, bolt, and dowel, were intact and undamaged. Magnetos remained attached to their respective mounting pads. Spark plugs were secured at their respective positions and had sustained thermal damage. The ignition harness appeared attached to each spark plug lead and had also sustained thermal damage.
The bowl section of the carburetor had separated, with fracture surfaces consistent with overload fracture. The throttle control was securely attached at the control arm of the carburetor. The fuel pump had been partially consumed by fire; its mounting flange remained attached at the mounting pad with safety wire in place and intact.
The propeller assembly remained attached at the engine at the crankshaft flange. The propeller blades showed significant S-bending, leading edge gouging, and chordwise striations, as well as thermal destruction.