WASHINGTON — The whistleblowers who exposed maintenance and inspection problems at Southwest Airlines told Congress their jobs were threatened and their reports of noncompliance were ignored for years.

Federal Aviation Administration inspector Douglas Peters choked up Thursday at a House hearing and needed a few sips of water to tell lawmakers about how a former manager came into his office, commented on pictures of Peters' family being most important, and then said his job could be jeopardized by his actions.

Rep. James Oberstar, D-Minn., said FAA managers' actions displayed "malfeasance bordering on corruption," adding that if presented to a grand jury, the evidence would result in an indictment.

The FAA last month took the rare step of ordering the audit of maintenance records at all domestic carriers following reports of missed safety inspections at Dallas-based Southwest. The airline was hit with a record $10.2 million fine for continuing to fly dozens of Boeing 737s, which carried an estimated 145,000 passengers, that hadn't been inspected for cracks in their fuselages. Southwest has said it will appeal the penalty.

Both FAA whistleblowers _ Charalambe Boutris and Peters _ said the agency views the airlines as its "customers" instead of companies to be regulated. They said the FAA's chief maintenance inspector at the time, Douglas T. Gawadzinski, knowingly allowed Southwest to keep planes flying that put passengers at risk, and that another inspector knew of the problem and did nothing.

Transportation Department Inspector General Calvin L. Scovel III echoed concerns about the FAA's inspection office responsible for Southwest Airlines, testifying that it had "developed an overly collaborative relationship" with the carrier.

"FAA's oversight in this case appears to allow, rather than mitigate, recurring safety violations," Scovel said.

His office found that the agency fails to protect employees who report safety issues and doesn't adequately respond to problems when they are identified. He recommended immediate action be taken to fix the air carrier oversight programs.

Herb Kelleher, Southwest's founder and executive chairman, apologized for allowing planes to fly that should not have. "Our people made engineering judgments they were not entitled to make," he said, adding that passenger safety was never compromised.

Southwest Chief Executive Gary Kelly said the airline increased the number, scope and frequency of audits and implemented more stringent requirements of maintenance plan changes after the problems were discovered. The airline will take further action after independent investigators, the FAA and Southwest staff finish their reviews, he said.

When FAA inspectors blew the whistle in March 2007, Gawadzinski was their superior. He's still employed by the FAA, but has no responsibility for safety decisions, said Nicholas Sabatini, the agency's associate administrator for aviation safety.

Oberstar disputed that assertion and said Gawadzinski had retained oversight responsibility after his removal from the Southwest office. Sabatini said he would look into it those claims and promised that the FAA will "take whatever action the law will allow" when the investigation is complete.

Gawadzinski was not asked to testify at Thursday's hearing because of the ongoing nature of the investigations and he was considered to be a hostile witness who would most likely refuse to answer questions that could have incriminated himself, according to a spokesman for the House Transportation and Infrastructure Committee.

Committee Chairman Oberstar said as long as the FAA views the airlines as customers "that culture of safety will not take hold and is not going to permeate the organization."

Sabatini said the FAA is a regulator and that he would immediately work to correct that internal problem of perception.

Still, the inspectors' concerns about Southwest, which the FAA first acknowledged a year ago, have since been confirmed, and the agency on Wednesday said it is investigating four airlines for failing to comply with various federal aviation regulations. It did not name the airlines.

In the last week alone, AMR Corp.'s American Airlines, Delta Air Lines and UAL Corp.'s United Airlines have canceled flights to perform unscheduled inspections of certain aircraft, and US Airways Group Inc. found problems on some Boeing 757s after a wing part from another plane fell off during a flight.

Spokesmen from Delta, United, Northwest Airlines, US Air and American said they have not been informed that their companies are the subject of an investigation. A Southwest spokeswoman said the carrier has not been informed of any additional investigation.

On Wednesday, the FAA announced a new reporting system designed to make it easier for inspectors to raise concerns and strengthening ethics policies aimed at easing potential conflicts of interests.

The agency will launch the system by the end of this month to provide employees an additional way to raise safety concerns they feel are not receiving the necessary attention or response from management, acting FAA Administrator Robert A. Sturgell said.

And by June 30, the agency will start a rule-making process to set a two-year "cooling off" period before former inspectors could work for an airline there were overseeing. That would match the time that new inspectors hired from industry must wait before they can oversee their former employer.

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AP Business Writers Dave Carpenter in Chicago, Harry Weber in Atlanta, Josh Freed in Minneapolis and Chris Kahn in Phoenix contributed to this report.