History of Flight
On December 26, 2016, at about 1318 Pacific standard time, an experimental amateur-built Express S-90, registration N176PA, was destroyed when it departed controlled flight and impacted terrain shortly after takeoff from runway 30 at Sierra Sky Park Airport (E79) in Fresno, California. The private pilot and his passenger sustained fatal injuries. The flight was a personal local pleasure flight.
Witnesses, including several pilots, observed the airplane climbing after takeoff when it made a sudden and rapid right turn. Reports indicated an abnormally steep climb after liftoff followed by a right turn, then a rapid descent and impact into a lake north of the airport. Some witnesses reported a nose-down attitude during the descent, and one described it as "falling." Engine sound initially seemed normal, but later varied among witnesses, with some reporting a decrease in power or "popping" sounds. No fire occurred, though the odor of gasoline was present at the site.
Personnel Information
The 47-year-old pilot held a private pilot certificate with an airplane single-engine land rating. His most recent third-class medical certificate was issued in July 2016. He began flight training in 1996 and received his certificate in 1997. At the time of the accident, his total flight experience was about 218 hours, including 31.1 hours in the accident airplane make and model, which he purchased in August 2016.
The passenger was a 32-year-old male with no FAA certificates or piloting experience. He was a family friend and a neighbor's son.
Aircraft Information
The Express S-90 was a fixed-gear, four-place, high-performance airplane designed by Composite Aircraft Technology and built by a third party in 2004. It was equipped with a Lycoming IO-540 series engine and a Hartzell three-blade controllable-pitch propeller. The most recent condition inspection was completed in May 2016, with the airframe having accrued 501 hours total time. An oil and filter change was performed in September 2016.
Weight and balance calculations using occupants' weight and two fuel loads indicated a gross weight below maximum but a center of gravity about 2 inches forward of the allowable envelope. However, the validity of these values could not be independently verified. The airplane had flown normally on previous flights with similar loading.
Weather and Airport
Sierra Sky Park Airport had no weather sensing equipment. At nearby Fresno Chandler Executive Airport, the 1315 automated observation reported visibility 10 miles, clear skies, temperature 10°C, dew point 3°C, and an altimeter setting of 30.28 inches of mercury. No wind data was available from that station; however, winds at Fresno-Yosemite Air Terminal were from 310° at 5 knots.
Wreckage and Impact
The airplane impacted marshy ground at the shoreline of a lake north of the airport, about 2,700 ft from the runway threshold and 80 ft below airport elevation. The wreckage came to rest in three major sections: wings, engine and cockpit, and aft fuselage, all partially attached. The engine and propeller were fully immersed in water. No pre-impact mechanical deficiencies were found in the engine, propeller, or flight controls. All damage was consistent with impact forces.
Medical Information
Autopsy reports listed the cause of death for both occupants as multiple skeletal and visceral injuries due to blunt impact. Toxicological tests for the pilot and passenger were negative for alcohol, carbon monoxide, and drugs.
Tests and Research
Comparison of airspeed reference values from the airspeed indicator, pilot's operating handbook, and a checklist revealed multiple discrepancies. The left aileron balance weights were found partially displaced due to a fractured rod; laboratory examination indicated a one-time overload from impact.
GPS data from a recovered Garmin GPSMap 496 showed the takeoff roll began at about 1317:10, with liftoff at 1317:33. The airplane achieved a maximum climb rate of 3,075 ft/min and reached a maximum altitude of 631 ft (310 ft above runway). It then entered a descent at up to 1,924 ft/min. The ground track indicated the airplane turned right, becoming perpendicular to the runway before arcing further. The accident takeoff profile was notably different from previous takeoffs: a longer ground roll followed by a very steep climb.