HISTORY OF FLIGHTOn April 29, 2014, at 2355 Pacific daylight time, an Airplane Factory Sling, N511NG, impacted mountainous terrain 5 miles southwest of the Barstow-Daggett Airport, Daggett, California. The certified flight instructor was seriously injured, and the sport pilot being instructed received minor injuries. The airplane was registered to, and operated by, the Sling Flying Club under the provisions of 14 Code of Federal Regulations Part 91, as an instructional flight. Night visual meteorological conditions prevailed for the flight, and no flight plan had been filed. The flight originated from Torrance, California, about 2130. The pilot who held the Sport Pilot certificate stated that they were about 10 miles southwest of the Barstow-Daggett Airport, and they could clearly see the airport lights. They had started their descent out of 5,500 feet mean sea level (msl) and were planning their entry into the airport traffic pattern when they suddenly impacted terrain twice and then came to full stop. The sport pilot secured the airplane's electrical equipment and fuel system, egressed the airplane, and attended to the CFI. He then called for assistance using a mobile phone. The Daggett ASOS (automated surface observing system) recorded at 2350 clear sky, visibility 10 miles, and wind from 260 degrees at 3 knots. Astronomical information shows that moon set had occurred at 2019. The accident occurred in a very sparsely populated area of high desert in Southern California, and that dark night conditions prevailed. WRECKAGE & IMPACT INFORMATION The airplane rested on its belly, positioned on a down hill slope of the east side of the ridge. The sloping desert terrain descends to the desert floor 2,000 feet below. The landing gear of the airplane had separated from the airframe at the initial collision with the ridge line. The wings, engine, and tail remained fully attached to the fuselage. The wreckage was recovered and transported to a secure facility in Phoenix, Arizona for further examination. The airplane wreckage was examined on May 13, 2014, by the NTSB Investigator-in-Charge. The fuselage was placed on a stand. The wings and engine had been removed from the fuselage by recovery personnel for the purposes of transportation. The engine was placed on a work bench. Flight control continuity was established from the cockpit to the ailerons, elevator, and rudder. The flaps were in the retracted position. The leading edges of both wings exhibited damage. The inboard section of the right wing exhibited hydraulic deformation along the front of the fuel tank. Engine control cables were traced from the cockpit to the firewall where the cables had been cut by recovery personnel. The airplane was equipped with two MLG Avionics Stratomaster Voyager Electronic Flight Information System (EFIS) displays, one positioned on the instrument panel in front of each cockpit seat. Aircraft power was applied to the EFIS displays. The display on the left side of the instrument panel powered up but the control buttons had been damaged and did not function. The display on the right side of the instrument panel powered up and the control buttons functioned appropriately. The display had been in night mode, which was changed during this exam to day mode for easier viewing. Various menus were displayed until the Terrain Warning setting menu was located. Once on that menu page, it was observed that the Terrain Warning box was not checked. The Collision Warning menu page displayed that the Collision Warning box was checked. A visual examination of the engine revealed no holes in the engine case, no oil leaks, all 4 cylinders were attached to the engine case, exhaust manifold and induction manifolds both in place on the engine. The propeller hub was attached to the crank shaft flange. The top spark plugs were removed, all exhibited electrodes light gray in color with no mechanical damage. The coloration and condition of the spark plugs were consistent with normal operation per the Champion Check-A-Plug chart (AV-29). The engine crankshaft was rotated by hand. Thumb compression was achieved on all cylinders, and the valve rockers were observed to move in concert. Both left and right carburetor bowls were removed. Both bowls contained undamaged floats and no fuel was observed. The propeller was a Whirlwind 3-bladed composite propeller. Two of the three bladed remained attached to the propeller hub, and all three blades exhibited leading edge damage. Examination of the cockpit shoulder harnesses revealed that the anchor cables for both pilot positions had separated in overload. The anchor cable separation was documented and the documentation was provided to the airplane manufacturer. The manufacturer updated the design and specified a larger diameter cable to be used for the shoulder harness anchor points.