Surprised engineers found a tiny crack in a hinge mechanism from the new shuttle Endeavour, meaning stress-related fractures now have been found in the same parts on all four of the nation's space shuttles.

But William Lenoir, NASA's associate administrator for space flight, said the latest crack found Thursday would not affect NASA's new launch schedule, which now lists six flights in 1991 and three launches in less than eight weeks starting with the shuttle Atlantis's planned takeoff around April 5."In the long run, it's not going to matter and it will not affect our schedule," he said.

Overnight, engineers hauled Atlantis to launch pad 39B for final flight preparations. The ship's five-member crew is scheduled to fly to Florida Sunday for a practice countdown next week that will set the stage for launch.

While the crack found Thursday in a hinge assembly taken from Endeavour will not affect the shuttle launch order, it could cause a minor additional delay for Discovery's planned takeoff next month on a military mission.