After stage separation, it detach the entire engine block (where most of the cost is), and a helicopter captures the parachute mid-flight! (See figure 2 from the PDF)
The issue with this though is it goes most of the way back to the STS; i.e. multi-month turn around instead of days/weeks. It saves manufacturing time and materials costs (not entirely due to fatigue checking etc), but does little for integration and turn around costs.
After stage separation, it detach the entire engine block (where most of the cost is), and a helicopter captures the parachute mid-flight! (See figure 2 from the PDF)