Already plagued by a report condemning its safety record, theAir Force is now investigating claims that air crash recordsin at least two cases were falsified to keep embarrassing facts from becoming public. In one incident, two Navy pilots died after they removed their oxygen masks and stripped off their clothes in flight, in order to "moon" another plane's crew, but then passed out and crashed. In another case, a plane crashed after a pilot allegedly let his wife take the controls. The coverup claims first surfaced last month in a report by Alan Diehl, former chief civilian safety official for the Air Force. A special panel of aviation experts will examine the report.