History of Flight
On June 1, 2017, about 1155 Pacific daylight time, a Cessna 180 airplane, N3683C, broke up in flight and impacted terrain about 7 miles west-northwest of Ventura, California. The private pilot, who was also the registered owner, sustained fatal injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a local personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed Santa Paula Airport in Santa Paula, California, about 1110.
Several witnesses near the accident site reported hearing a loud sound. Two witnesses stated that before the loud sound, the engine sounded like it was powering up. Another witness reported looking up after the loud sound and seeing the airplane spinning toward the ground, with the engine and both wings separated from the airframe. That witness added that the tail section remained attached to the main cabin when first observed.
Personnel and Aircraft Information
The pilot held a private pilot certificate with an airplane single-engine land rating and was issued a Federal Aviation Administration third-class medical certificate on May 11, 2016, with a limitation requiring corrective lenses. On the medical application, the pilot reported 1,100 total flight hours and 50 hours in the preceding 6 months. The pilot's logbook was not located during the investigation.
The airplane, manufactured in 1954, was a high-wing, fixed-gear, all-metal design. It was powered by a 230-horsepower Continental O-470-S engine driving a two-bladed McCauley 2A34C66-NP constant-speed propeller. The most recent annual inspection was completed on May 14, 2017, at a total time of 4,566.1 hours. Maintenance history included repairs to the outboard right wing and right elevator after a ground event in January 2005, and a rebuild of the horizontal stabilizer, repair of the right elevator, and replacement of pitch trim actuators in November 2016.
The Airplane Owner's Manual specified maximum load factors of +3.8 g and -1.5 g, a maximum structural cruising speed of 160 mph (139 knots), and a maneuvering speed (Va) of 122 mph (106 knots). Full flight control application at speeds above Va could produce g-loads exceeding design limits.
Estimated weight and balance calculations, based on factory basic weight, pilot weight from FAA records, and assumed fuel load of 55 gallons, indicated the airplane was several hundred pounds below its maximum gross weight of 2,550 lbs and within center of gravity limits.
Meteorological Information
The 1151 weather observation at Oxnard Airport, about 10 miles southeast of the accident site, reported wind from 240° at 7 knots, visibility 10 statute miles, scattered clouds at 2,300 ft, temperature 19°C, dew point 13°C, and an altimeter setting of 29.89 inches of mercury. No significant weather or turbulence was reported or forecast in the accident area. Weather surveillance radar detected no echoes over the area for one hour before and after the accident. An AIRMET for instrument flight rules conditions was valid along the western coast, but no turbulence, low-level wind shear, or SIGMET advisories were in effect. Wind modeling estimated a high probability of moderate or greater turbulence between 2,300 ft and 3,300 ft mean sea level.
Wreckage and Impact Information
The airplane impacted mountainous terrain at an elevation of about 1,015 ft mean sea level, with debris scattered across an oil field. The main wreckage, consisting of the fuselage from the nose to just before the vertical stabilizer, came to rest upright between two parallel power lines, one of which was fractured beneath the fuselage. Most debris was found within about half a mile south of the main wreckage, with lighter pieces farther south. A section of the right wing was located about 1.5 miles south. All major components were recovered.
The engine and propeller separated and were found embedded in an asphalt road about 510 ft southwest of the fuselage. The engine case fractured through the mounts, with fractures displaying a dull, grainy appearance consistent with ductile overload. Examination revealed no preimpact malfunctions that would have precluded normal operation. No damage or paint transfer marks suggested a collision with a foreign object. Paint transfer on the right side of the vertical stabilizer matched the color of other airplane parts, consistent with being struck during the breakup.
Structural examination showed both wings separated due to negative overload failure. No preexisting corrosion or cracking was observed on spar fracture surfaces. The right horizontal stabilizer was deformed down and aft, with its leading edge twisted down about 90°, and the right elevator exhibited similar downward deformation. The left horizontal stabilizer was deformed upward about 20°. Control continuity was established to all primary flight controls and pitch trim; all control cables were intact before the breakup, with tension overload fractures. The pitch trim actuators functioned normally, and the cockpit trim wheel was slightly forward of the takeoff position.
Medical and Pathological Information
An autopsy conducted by the Ventura County Medical Examiner's Office determined the cause of death as blunt force injuries. Toxicological testing by the FAA's Bioaeronautical Sciences Research Laboratory was negative for ethanol and all tested drugs.
Tests and Research
Radar data from 1152:42 showed the airplane flying a relatively steady southwesterly heading (230°–240°). Groundspeed increased from 82 to 127 knots over 67 seconds, with calculated calibrated airspeeds exceeding the maneuvering speed of 106 knots but below the maximum structural cruising speed of 139 knots. Any large control surface deflection during this period could have put the airframe at risk for structural overstress. At 1155:31, groundspeed dropped significantly and the flight track deviated. The final primary radar returns were not indicative of continued flight and were likely from individual pieces of the broken airplane. No other radar returns were noted near the accident site.