In the early seventies, Neil Williams doing aerobatics in a Zlin had a spar failure. With the failed wing rising, he rolled inverted, locked it back in place and flew upside down back to the field. ( Hullavington in England I think it was). Just prior to the flare he rolled the right way up and landed, just as the wing completely failed. Great demonstration of stick skills and hard to believe the same man then killed himself by flying into a mountain north of Madrid in 1977.