What happened
During flight testing for a new cargo pod installation, an aircraft exhibited irregular behavior, leading engineers to pause the testing program. To ensure safety during subsequent flights, the chief design engineer authorized a more conservative center of gravity position, specifically for takeoff and flaps-up configurations. However, prior to the final test flight, the flight crew modified the approved test plan by adding spin entries using the landing flap configuration without obtaining necessary authorization or consulting the design engineer.
During the flight, the crew performed two wings-level spins using left rudder and right aileron with flaps in the landing position. A third spin was initiated from a 30-degree left-bank turn. While the aircraft initially entered a standard spin, the crew's recovery inputs failed to arrest the descent, and the aircraft transitioned into a fully developed spin.
As the aircraft descended, the crew attempted to deploy the anti-spin parachute. After multiple failed attempts to activate the system, the pilots reached an altitude approximately 500 feet above the established bailout minimum and executed a bailout. The aircraft subsequently struck the ground and was destroyed. There were 2 fatalities.
Findings
An investigation into the anti-spin parachute system determined that the mechanism failed because half of the connector hook had opened. This mechanical failure allowed the activation pin lanyard to disengage, preventing the parachute from deploying. The investigation concluded that the unauthorized addition of landing flap spin entries to the test plan was a primary factor, as the crew bypassed established safety parameters and testing build-up procedures.