American Airlines has cancelled thousands of flights causing chaos in airports across the US.The travel plans of around 100,000 passengers were disrupted after the company grounded its fleet of MD-80s airplanes because of a wiring problem.The fault, which could cause a short-circuit or even a fire and explosion, was discovered on Tuesday by government inspectors.The Federal Aviation Administration (FAA) asked the airline to fix the bundling of wires in the backup power system for the fuel pump of the MD-80s airplanes in September 2006.Airline officials thought the problem was fixed last month, but this week FAA inspectors found issues on more than a dozen planes.At Chicago's O'Hare Airport, one man said he "didn't buy" the excuse."They should have been doing this maintenance all along a few at a time instead of creating this havoc at the airport, I mean it's nuts," said Wayne Wishnew.Most of the chaos occurred at Dallas and Chicago airports, where more than half of the cancellations are concentrated.