The final test flight of the experimental plane Voyager, whose pilots hope to set a new global distance record, was canceled because of "minor but critical problems," a spokesman said. The Voyager, piloted by Dick Rutan and Jeana Yaeger, had been scheduled to leave Edwards Air Force Base on a two-day test flight as a prelude to a 12-day flight around the world without refueling. Instead, the craft was returned to the Mojave Civilian Test Flight Center after problems were encountered in its seven-hour flight to Edwards on Saturday, said Dan Card, a project spokesman. Aluminum filings were found in an engine drain, one of the plane's alternators malfunctioned and minor electrical glitches were detected in the cabin area. None of the problems was serious, another project spokesman, Peter Riva, said. He said the plane may be ready for its test flight in four or five days. The global flight was originally scheduled for Sunday.