The cause of the engine fire that left the cruise ship Carnival Triumph without power for five days was a leak in a fuel oil return line that sprayed onto a hot surface, the Coast Guard announced Monday. Lt. Cmdr. Teresa Hatfield, head of the U.S. Coast Guard Marine Casualty Investigation Team, said the oil caught fire when it made contact with the hot surface. She said the suppression system kicked on immediately and that the ship’s crew “did a very good job” in responding.