Federal officials have hit American Airlines with a record penalty of $24.2 million over maintenance lapses that caused thousands of canceled flights in 2008.

The Federal Aviation Administration said Thursday that American failed to take steps to prevent chafing of electrical wires in the wheel wells of its McDonnell Douglas MD-80-series jets.

The FAA says the wiring could have led to fires and fuel-tank explosions, but American says it was a minor matter of leaving too much space between clips that held bundles of wire together. The airline says passenger safety was never threatened.

American can challenge the proposed penalty and negotiate to reduce it. American is a unit of AMR Corp.