History of Flight
On April 3, 2015, about 1230 Pacific daylight time, an experimental amateur built Quicksilver Enterprises Inc. MXL II, registration N476VB, was destroyed when it impacted terrain near the Petaluma Municipal Airport (O69), Petaluma, California. The airplane was registered to and operated by the pilot under Title 14 Code of Federal Regulations Part 91. The student pilot, the sole occupant, was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed. The local flight originated from O69 at an unknown time.
A witness on the first tee of the Adobe Creek Golf Course observed the airplane at about 1,000 feet above ground level. He estimated winds from the north at 15 to 20 mph. Later, from the second tee, he saw the airplane pointed into the wind on a northerly heading toward O69, and it appeared to make no headway. After about 20 seconds, it entered a slow left 180-degree turn. He heard the engine increase, then stop, and saw the airplane falling straight down with both wings appearing upward, as if collapsed or folded. It descended below a tree line.
A second witness, also playing golf, saw the airplane flying east, then turn right into the wind. When he looked up, the wings were folded upward, the airplane entered a spin, and descended. He estimated wind at 10 to 20 mph with gusts. A third witness on a walking trail saw the airplane suddenly descend almost vertically, traveling very fast, followed by both wings folding upward.
Personnel Information
The pilot, age 51, held a student pilot certificate issued January 23, 2014. His logbook showed 66 hours total flight time, 65.1 hours in the accident make/model, 36.2 hours solo, with 3.8 hours in the previous 30 days. He had applied for a medical certificate in 2003 but was denied due to a reported severe head injury and limited range of motion in his left elbow. A subsequent application in December 2004 was also denied after he failed to provide requested information.
Aircraft Information
The two-seat, high-wing, fixed-gear airplane, serial number 062, was kit-built in 1984. It was powered by a Rotax 503 engine rated at 50 horsepower and equipped with a Whirlwind two-bladed composite propeller. The most recent conditional inspection was on November 12, 2014, at tach time 28.23 hours; the most recent maintenance on March 24, 2015, at tach time 45.34 hours, included installation of a 4.5-gallon seat fuel tank.
Meteorological Conditions
At 1235, the automated weather observation station at Gnoss Field Airport (DVO), about 6 miles west, reported wind from 300 degrees at 4 knots, visibility 10 statute miles, clear sky, temperature 19°C, dew point 5°C, and altimeter 30.20 inches of mercury.
Wreckage and Impact Information
The airplane impacted an open field adjacent to a tree line about 1.3 miles southeast of runway 29, coming to rest near vertical. All major structural components were present. Debris, including the engine and one propeller blade, was within 15 feet. The left wing remained partially attached via flying and landing wires but separated at the forward spar attach point; the forward spar was fractured mid-span, consistent with overload. The right wing remained attached via forward spar mounts and all wires; the forward spar was bent and twisted, consistent with impact. The empennage was intact. Flight control continuity was established. The airframe was impact-damaged; the ballistic parachute was dislodged and extended about 15 feet. The engine was separated; carburetors and propeller gearbox were separated. The separated propeller blade had a nick consistent with contact with a landing wire. Both carburetors had intact floats and needle valves; engine crankshaft rotated with compression on both cylinders.
Medical and Pathological Information
An autopsy determined the cause of death as multiple extreme blunt force injuries. The pilot's ex-wife reported he had changed his name due to a traumatic brain injury that precluded obtaining a pilot's license, and he was receiving disability benefits under a different name. Toxicology testing identified tetrahydrocannabinol (THC) at 3.3 ng/ml in cavity blood and diphenhydramine at 0.634 ug/ml in cavity blood. Diphenhydramine is a sedating antihistamine with warnings about impaired ability for hazardous tasks. Postmortem redistribution was noted for both substances.
Tests and Research
Examination of left and right wing spars at the NTSB Materials Laboratory revealed overstress separations with no indications of preexisting cracking or corrosion. The right spar failed after about 45 degrees of deformation; the left spar failed in tension bending.