A method and kit for retrofitting an inertia reel door onto the seat back of a preconstructed ejection seat is disclosed. The method includes removing existing rivets from the seat back exposing rivet holes. Alignment holes are then drilled into the seat back. An aperture is cut into the seat back along flanges of an upper support bracket and a drogue chute bracket. A doubler is aligned with the rivet holes and alignment holes in the seat back and then attached to the seat back. A track is attached to a wall of the aperture and an inertia reel is mounted to the track. An inertia reel door is attached to the doubler.