BROOMFIELD, Colo.—David Delucia was settling back into his airplane seat and starting to relax on his way to a long-awaited vacation when a huge explosion and flash of light interrupted an in-flight announcement and put him in survival mode. The Boeing 777-200, headed from Denver to Honolulu on Saturday with 231 passengers and 10 crew aboard, suffered a catastrophic failure in its right engine and flames erupted under the wing as the plane began to lose altitude. As Delucia and his wife prepared for the worst, people in this Denver suburb reacted in horror as huge pieces of the engine casing and chunks of fiberglass rained down on a sports fields and on streets and lawns, just missing one home and crushing a truck. The explosion, visible from the ground, left a trail of black smoke in the sky, and tiny pieces of insulation filled the air like ash. The …