What happened
On March 29, 2014, a Worthington Sonerai 11L experimental airplane, registration N639 and N63917, crashed near Highlands Ranch, Colorado. The flight was a local operation under Part 91 regulations and was not operating under a flight plan. Weather conditions were visual meteorological conditions (VMC) with a visibility of 10 miles and winds from 330 degrees at 6 knots.
The pilot had purchased the aircraft in November 2013 and had performed his first flight in the airplane on the morning of the accident. That initial flight was ended early because of a leak in the fuel sight gauge. After making repairs, the pilot took off for a second flight. Witnesses observed the aircraft struggling to remain airborne and noted the engine was running roughly as it approached an open field. The airplane was seen crossing power lines, rolling to the left, and descending into the ground, followed by a post-impact fire.
The pilot sustained 1 fatal injury, and the aircraft was destroyed.
The investigation
Investigators found clear tubing and materials for replacing a fuel sight gauge in the pilot's hangar, along with a cracked section of tubing in a trash can consistent with the sight gauge.
An examination of the engine revealed the propeller blades were broken and splintered approximately eight to ten inches from the hub. While the cylinder head covers were separated, the rocker arms moved freely when the propeller was rotated by hand. The fuel system included a 10-gallon aluminum fuel cell and a sight gauge made of transparent rubber hose; however, the sight gauge was not recovered from the wreckage.
While the carburetor sustained impact and fire damage, the flight control continuity was verified from the cockpit to all control surfaces. No mechanical anomalies were found in the available wreckage that would have prevented normal operation prior to the accident.