Event Summary
The pilot reported that shortly after turning crosswind at an altitude of 400 feet above ground level, he noted a change in engine noise, and the airplane started to sink rapidly. Troubleshooting revealed that the spin parachute had inadvertently deployed.
Pilot Actions
The pilot attempted to jettison the parachute, but he was unsuccessful because he followed procedures for a different design parachute. He stated that he was losing altitude rapidly, so rather than attempt to jettison again, he concentrated on making a successful forced landing.
Post-Accident Investigation
Post-accident investigation revealed that the safety pin had worked loose, allowing the parachute to deploy.