Connectors Eyed Other experts said the tail fin on Flight 587 wouldn't have broken free unless something was wrong with the materials that attached it to the fuselage. The flanges between the tail fin and the fuselage broke off. Such flanges are made of a composite graphite material that NTSB investigators are closely examining. Hansman said the composite materials endure fatigue better than metals, but they are more easily damaged by impact. "And they can have internal damage that can't be seen," Hansman said. Even so, the plane was designed so that one or more flanges could crack and the tail would remain intact. "You'd be talking about a series of undetected cracks or failures," Darcy said.