On June 4, 2018, about 1152 Pacific daylight time, an Australian registered GIPPSAERO PTY LTD, GA10 airplane, VH-XMH, was destroyed after it impacted terrain following an unrecoverable spin, and the unsuccessful deployment of the anti-spin parachute near Mojave, California. The airplane was registered to GIPPSAERO PTY LTD and operated by GIPPSAERO PTY LTD in conjunction with the National Test Pilot School (NTPS) as a visual flight rules test flight under the provisions of 14 Code of Federal Regulations Part 91.715 Special Flight Authorization when the accident occurred. The Australian certificated commercial pilot and the United States certificated airline transport pilot sustained minor injuries. Visual meteorological conditions prevailed, and company flight following procedures were in effect. According to the airplane manufacturer, the purpose of the flight was to conduct spin trials with the GA-10 airplane fitted with a cargo pod installation. Initial spin trials with the cargo pod were completed in Australia with company pilots, and the aircraft configured well away from the critical flight conditions identified during the original airplane certification spin testing. Due to scheduling and personnel constraints, it was decided to send the airplane and company personnel to NTPS to conduct the more critical spin tests. The flight tests commenced and proceeded until May 31, 2018, when the airplane exhibited some aberrant behavior, and the manufacturer's Chief Design Engineer (CDE) was consulted. To provide a margin of safety for further flights, a forward CG position was authorized for flaps up and flaps takeoff entries, in an effort, to gain more information into the airplane's aberrant behavior on the previous flight. At the final briefing, prior to the next flight, spins with landing flaps were added by the flight crew without consultation or authorization from the CDE. According to the pilot flying, the flight departed about 1105 PDT and a stall series consisting of stalls with flaps up, flaps takeoff and flaps landing was completed prior to any spin entries, with stall characteristics normal and benign. The first spin entry was a wings level, power on, flaps landing spin with left rudder and right aileron. He said that the recovery took longer than expected, and the decision was made to repeat the test point. A repeat of the same entry resulted in a very similar spin with the recovery at one additional turn. The second test point (third spin entry) was flown in the same configuration as the first two, except that the entry was from a 30° left-bank turn. The airplane entered a normal spin and at one turn, flight controls were inputted for a normal recovery; however, the airplane settled into a fully developed spin. After 3 turns, the pilots in the chase aircraft called "three turns". The control yoke was held full forward with full opposite rudder, and right aileron was inputted, in an attempt, to affect yaw rate, to no avail, so the control yoke was returned to neutral, full forward and full right rudder. Around 10,000 ft, the pilots in the chase aircraft called "chute, chute, chute". The anti-spin parachute lever was pulled aft; however, the anti-spin parachute did not deploy even after repeated attempts. At about 8,500 ft msl, 500 ft above the briefed minimum bailout altitude, both pilots called for and executed a bailout. A postaccident examination of the anti-spin parachute system revealed that one half the connector hook had opened allowing the activation pin lanyard for the anti-spin parachute to become disengaged. The closest weather reporting facility was Mojave Air and Space Port (KMHV), Mojave, California, about 9 miles north of the accident site. At 1200, a METAR from KMHV was reporting, in part: wind from 300° at 15 knots, gusting 20 knots; visibility, 10 statute miles; clouds and sky condition, clear; temperature, 93° F; dew point 39° F; altimeter, 29.91 inches of mercury.