DALLAS (CBSDFW.COM) – The FAA has stepped up oversight at Southwest Airlines’ maintenance stations across the country.

A spokesman says the agency did so Friday, the same day the airline declared an operational emergency at several of its facilities nationwide.

On Tuesday, Southwest added Dallas to the list of maintenance stations under the operational emergency.

Southwest has said since Friday, about 40 of its 750 aircraft, about twice as many as normal, have been taken out of service each day for unscheduled repairs.

The FAA says as part of its increased oversight, there are more spot checks conducted as needed.

The agency’s spokesman says this is standard practice when airlines are going through labor issues.

The airline and its mechanics union, the Aircraft Mechanics Fraternal Association or AMFA, are exchanging barbs and pointing fingers at one another.

Both sides have been negotiating a new contract for the past six and a half years.

Rogge Dunn is a labor law attorney in Dallas. “This is the labor law equivalent of a very important game of chicken.”

Dunn says disputes during contract negotiations are common. “Slow downs and work stoppages on purpose, which is an unfair labor practice are common, and of course, the union is going to say we’re not showing down because we’re in a fight over our contract, we’re doing it for safety and throw the PR back to the company.”

On Tuesday night, Southwest’s COO Mike Van de Ven issued a statement saying, “AMFA has a history of work disruptions and Southwest has two pending lawsuits against the union. We will be investigating this current disruption and exploring all possible remedies. On February 12th, just days after our last negotiations session with AMFA, we experienced an unprecedented number of out of service aircraft in four specific maintenance locations despite no change in our maintenance programs, no changes in leadership, and no changes in our policies and procedures.”

In response, AMFA issued a statement of its own Tuesday night. “Southwest Airline’s scapegoating of its expert Aircraft Maintenance Technicians does not bode well for the airline’s safe operations. Safety is, and always will be, our number one priority. For Southwest’s leadership to connect the airline’s self-declared “operational emergency” to collective bargaining negotiations is simply an attempt to divert attention away from the airline’s safety issues.”

A CBS News investigation last month found some of the airline’s mechanics felt pressured to return aircraft to service faster.

AMFA says after the story, Southwest’s technicians are less afraid to write-up legitimate issues.

When asked how these disputes normally end up, attorney Rogge Dunn said, “It depends on who flinches first. This could go on for weeks, it could go on for months.”

At the terminal, there was little evidence of the disruptions– but, plenty of proof that Southwest customers are a loyal bunch.

“They’re  on time. Often early  Will let you change your flights. Bags are free,” explained Brent Shreiner. “Service is great.”

“Oh, I love Southwest,” exclaimed Shirley Staten, who says she travels half a dozen times a year and will always try to do so on Southwest. 

“I think they will resolve it. They care about their employees, they know that employees can make or break their company and so they will do whatever they need to, to make sure their employees are happy, because happy employees make happy customers.”

Lindsey Miller flew in from Denver and is also loyal to Southwest, but admits it is not a comforting thought to fly on a plane checked out by a mechanic who may be disgruntled.

“I would hope they are happy and care about their job,” says Miller.  “I wouldn’t want to know that they’re just putzing around and just letting things through.”

Most passengers we spoke with insisted that they trusted the company and its employees enough to not jeopardize passenger safety.

“I think the people have enough personal integrity to not let that happen,” says Staten.  “They may not come in, but I don’t think they would purposefully do anything to cause a problem with the plane.”

But frequent Southwest traveler Linda Giarruso, whose Wednesday flight was cancelled due to weather, said she may take a break from her preferred airline for a while.

“Definitely safety (concern). Because I don’t like to fly to begin with. I like to travel, but I don’t’ like to fly. So when I hear things like that, it concerns me.”

CBS 11’s Robbie Owens and Andrea Lucia contributed to this report.