The Federal Aviation Administration should "clean house from top to bottom" and has too cozy a relationship with the airlines, the head of a congressional committee investigating airline safety inspections said Friday.

The problems have led to the sort of lax enforcement that allowed Southwest Airlines Co. to fly at least 117 aircraft past mandatory inspection deadlines, said Rep. James Oberstar, Transportation and Infrastructure Committee chairman.

Oberstar also said he believes similar violations may have occurred involving other airlines, but that those who have such evidence are afraid to come forward.

"Complacency has likely set in to the highest levels of FAA management," the Minnesota Democrat said in a Capitol Hill news conference. "I think we have seen the pendulum swing away from vigorous enforcement of compliance toward a carrier-favorable, cozy relationship with the airlines."

Oberstar said his committee has seen evidence that Southwest Airlines, with the complicity of the FAA, allowed its aircraft to fly in violation of federal aviation regulations.

Forty-seven of the Southwest Airlines aircraft were overdue for fuselage inspections and 70 were overdue for mandatory inspections of critical rudder control systems. Those numbers may overlap, he said. They flew at least 1,457 flights, he said.

Southwest has said it voluntarily disclosed its maintenance violations, but Oberstar said the law requires that planes be grounded until they are in compliance. The Southwest planes continued to fly with full knowledge of an FAA supervisor, Oberstar said.

"FAA needs to clean house from top to bottom. They need to take corrective action internally. They need to hire new inspectors. They need to give them a safety mission. They need to install a new safety compliance attitude among their inspection work force," he said.

His news conference came a day after the FAA said it would seek a $10.2 million fine against Southwest Airlines for failing to inspect older planes for cracks and then flying them before inspections were done.

The FAA said Southwest operated nearly 60,000 flights in 2006 and 2007 using 46 planes that had missed inspections for possible fatigue-related cracking on the fuselage areas.

Southwest has said it complied with regulators' requests and would contest any penalty.

Southwest Chief Executive Gary Kelly said Friday that the penalty was unfair, calling the missed inspections "a gap in our documentation" that the airline voluntarily reported to the FAA.

"We worked out with the FAA how to fix that problem, and we fixed it," Kelly said on CNN. He said the airline has a safe history record and is "safer today than we've ever been."

Southwest has never had a crash-related fatality aboard one of its planes, although a boy was killed in 2005 when his family's car was struck by a Southwest jet that overran a runway during a snowstorm at Chicago's Midway Airport. Federal investigators cited pilot error.

An FAA spokesman defended the agency's work.

"We believe the system we have now is working well, and that's borne out by the extraordinary low accident rate," said the spokesman, Les Dorr, "but as an organization we are always looking for ways that we can do things better."

Dorr also disputed Southwest's claim that the civil penalty was unfair.

"It was very clear what the airworthiness directive called for," he said, referring to the order to inspect older Boeing 737 planes every 4,500 flights. "Following the airworthiness directive was the right thing to do, and when Southwest did the wrong thing, that's why we took the enforcement action."

Oberstar said the committee's investigation was begun after two whistleblowers approached it after years of trying to correct the problems.

A maintenance supervisor at Southwest had previously worked for the regulatory agency, Oberstar said.

He rejected arguments the planes were safe because no accidents or fatalities occurred.

"Any aircraft that does not comply with FARs — federal aviation regulations — is not safe to fly," Oberstar said.

Oberstar said legislation should be passed to require a "cooling off period" for inspectors at the FAA, barring them from leaving the agency and immediately going to work for an airline.

The FAA also should consider rotating inspectors to avoid too cozy a relationship between the regulator and the regulated, he said.