History of Flight
On November 23, 2012, about 1530 Pacific standard time, a Sater Coot A-Amphibian experimental amateur-built airplane, N8VS, was substantially damaged after a loss of control and impact with terrain while maneuvering near Calaveras County-Maury Rasmussen Field Airport (CPU), San Andreas, California. The pilot, the sole occupant, sustained fatal injuries. The flight was conducted under 14 CFR Part 91 without a flight plan. Visual meteorological conditions prevailed for the local flight, which had departed CPU about five minutes prior.
Three witnesses provided statements. Witness #1, a rated pilot who had flown with the accident pilot earlier that day, reported that on the first flight the landing gear was left extended and the canopy was off. The pilot commented on the increased rudder required for turns. After landing and refueling, a second flight with witness #2 was flown with the canopy on but gear still extended. The pilot expressed dissatisfaction with the handling with gear down and decided to fly again to test gear-up performance. Witness #1 observed the takeoff, saw the gear retract, and noted a faster climb. The airplane flew about 2 miles before turning downwind. On base leg, the bank angle increased to about 60 degrees, and at about 800 feet agl, the airplane nosed down, appearing to stall. Power was applied, but the airplane entered a spin. After the first revolution, the leading edge of a wing separated; after the second, the other wing appeared to separate.
Witness #2, also a rated pilot who accompanied the pilot on the second flight, stated that after landing, the pilot said he would go up to cycle the gear. Witness #2 observed the departure and gear retraction without issues. The airplane turned base leg, then entered a 75-80 degree descending left bank and 90-degree left turn, rolling inverted. It then went into a near-vertical nose-down attitude, and the right wing separated. The left wing remained attached as the airplane went out of sight. No change in throttle or rpm was heard.
Witness #3, driving on a highway near the airport, reported seeing the airplane flying erratically, then a small piece separated, followed by a vertical dive, and another piece separated.
Personnel Information
The pilot, age 68, held a private pilot certificate with single-engine land, multiengine land, and instrument ratings. His most recent FAA third-class medical was issued December 1, 2010. Logbooks indicated 5,138 total flight hours, with no breakdown by category. The last logbook entry was July 24, 2012, with no recorded time in the accident aircraft. The most recent flight review (FAR 61.56) was April 27, 2008, and instrument proficiency check (FAR 61.57(d)) was September 13, 2009.
Aircraft Information
The Sater Coot A-Amphibian (serial number Sater Coot #1) was a low-wing, tricycle-gear, two-seat amphibious homebuilt airplane, powered by a single Franklin 6A&6V335 engine (210 horsepower) in a pusher configuration. No current maintenance records were recovered.
Meteorological Information
At 1555, the automated weather at Stockton Metropolitan Airport (35 nm southwest) reported wind 290° at 5 knots, visibility 10 miles, sky clear, temperature 18°C, dew point 11°C, altimeter 30.18 inHg.
Wreckage and Impact Information
The accident site was about 1.25 nm south of the approach end of runway 31 at CPU. The main wreckage (fuselage, engine, empennage) was inverted. The right wing was 90 feet north-northwest; a large section of the left wing (minus leading edge) was 40 feet south; the left leading edge was 20 feet west of the right wing. The terrain slope varied 10-20 degrees. The cockpit was destroyed; the nose tip was the initial impact point. Fabric and wood fragments were scattered up to 200 yards downhill.
Medical and Pathological Information
An autopsy attributed the pilot's death to multiple traumatic injuries. Toxicological testing at CAMI found no ethanol or listed drugs in liver; carbon monoxide and cyanide tests were not performed.
Tests and Research
The Airworthiness Group examined the wreckage. The right wing was essentially intact except for a missing lower inboard trailing edge. The front and rear spars were fractured about 17 inches outboard of attach points. Fracture features indicated tension and compression failures with no pre-existing condition. The left wing was in three main pieces. The front spar was fractured similarly; one section had a diagonal cut with a matching U-shape cut in the leading edge skin. No signs of rot or pre-existing conditions were noted.