Once had girlie nav student following me through on an inverted push up to stall turn.. inadvertantly departed the aircraft and entered inverted spin. When I tried to recover I thought the I had broken the aircraft as the control col was stuck full forward, checked G for overstress, checked height, checked needle checked student... found problem eyes closed pushing as had as she could. To three shouts to get her to let go.
Performed Grob emergency recovery drill (let go of everything) ac recovers go home beers all round.
