Background
Aircraft manufacturer personnel were conducting spin flight testing for the installation of a cargo pod when the airplane exhibited aberrant behavior, prompting a halt to the testing. The chief design engineer (CDE) was consulted and authorized a forward center of gravity position for flaps-up and flaps-takeoff entries, aiming to provide a safety margin and gain insight into the airplane's previous behavior.
Flight Test Events
At the final briefing before the subsequent flight, the flight crew added spins with flaps in the landing configuration (flaps landing) to the test plan without consulting or obtaining authorization from the CDE. According to the pilot flying, after completing two wings-level, power-on, flaps-landing spins with left rudder and right aileron, a third spin entry was flown in the same configuration but from a 30° left-bank turn. The airplane entered a normal spin. At one turn, control inputs were made for a normal recovery; however, the airplane settled into a fully developed spin.
Accident
When recovery attempts failed, the crew decided to deploy the anti-spin parachute. After repeated unsuccessful attempts to deploy the parachute, and when the airplane's altitude reached approximately 500 ft above the briefed minimum bailout altitude, both pilots called for and executed a bailout. The airplane impacted the ground and was destroyed.
Investigation Findings
A postaccident examination of the anti-spin parachute system revealed that half of the connector hook had opened, allowing the activation pin lanyard for the anti-spin parachute to become disengaged. Based on the airplane's previous aberrant behavior and the conservative parameters set by the CDE, it is not likely that the CDE would have authorized abused spin entries without prior testing buildup. The investigation concluded that the flight crew made an inappropriate decision to introduce flaps-landing entry spin testing, and the failure of the anti-spin parachute contributed to the accident.