Incident Overview
During a parachute jump activity, two parachutists were on the airplane's jump step. One parachutist began a cadence used for jumping from the step. According to the jumpmaster, the parachutist initiated an exaggerated rocking motion. During this motion, the reserve parachute's ripcord pin protective flap brushed against the airplane's open door. The flap opened, and the pilot chute deployed, pulling the reserve parachute from its container.
Collision with Aircraft
As the parachutists jumped, a steering line from the deploying parachute struck the airplane's right horizontal stabilizer. The collision caused the stabilizer to bend downward.
Parachutist's Account
The jumper whose parachute prematurely deployed reported that the Velcro on the ripcord pin's protective flap was worn. He stated that the flap would frequently dislodge.