Pirates Of The Caribbean movie-makers are terrified Keith Richards may suffer another fall when he shoots his scenes for the third installment of the hit franchise. The legendary Rolling Stones hellraiser fell out of a tree in Fiji in April (06), and subsequently underwent skull surgery. Following the Brown Sugar hitmaker's recovery, he is signed up to appear as the father of Johnny Depp's CAPTAIN JACK SPARROW. Richards will be required to climb the stairs of a pirate ship and nervous director Gore Verbinski says, "For a guy who falls out of coconut trees, those steps could be a problem."