Aviator Gus McLeod launched on Sunday for a second try to circumnavigate the world crossing both poles -- a flight he attempted once already -- but a gear malfunction has delayed his plan for at least a week. McLeod took off from Gaithersburg Airpark in Maryland, and heard a rattling noise from his experimental Firefly aircraft. He made a precautionary landing in Frederick, about 30 miles away, and upon touching down, the nose gear collapsed on the runway. "The bolt supporting the nosegear suffered metal fatigue and broke," McLeod said. The gear will be rebuilt with stronger support, and the trip should continue next week. "This expedition is off to a rough start," said Edward Park, McLeod's publicist, "but the damage is minimal." McLeod's solo flight to the North Pole in an open-cockpit biplane was chronicled in a National Geographic "Explorer" television special and in a book by McLeod, "Solo to the Top of the World." Last year, he attempted to cross both poles in the Firefly, but had to turn back over Antarctica due to icing problems.