American Airlines could face a fine in the ballpark of $10 million for safety violations involving wiring in its large MD-80 fleet, according to a government official familiar with the nearly completed federal investigation.

While the Federal Aviation Administration hasn’t decided what fine to propose in the probe expected to wrap up in mid-March, there is sentiment to top the record $10.2 million against Southwest Airlines in March 2008, said the official, who was not authorized to discuss publicly the two-year investigation and spoke on condition of anonymity.

The Southwest fine was for 60,000 flights involving planes that had missed required examinations for structural cracks. That case settled for $7.5 million a year later.

The FAA itself is coming under criticism by a government watchdog for lax oversight of American’s aircraft maintenance.

Loose fastening in 290 of American’s MD-80s led to wire damage in several dozen planes and, in at least a few cases, an electrical discharge that’s a potential fire threat, according to the government and industry officials who spoke Tuesday. They asked not to be identified because they weren’t authorized to speak publicly about the two-year investigation.

The airline and officials with its mechanics union said its MD-80s never had that second type of problem, known as electrical arcing, and long has contended that safety never was jeopardized.