WASHINGTON — The maintenance woes that have plagued the airline industry in recent weeks aren't tied to the run-up in jet fuel prices and economic slump that have been putting the squeeze on airline profit margins, an industry leader says.

"No airline in its right mind is going to scrimp on maintenance, no matter what the economy is like," Southwest Airlines Executive Chairman Herb Kelleher said after testifying Thursday at a House hearing on the Federal Aviation Administration oversight of the nation's airlines.

Instead, the added attention to maintenance appears to be the price airlines are paying for a close relationship with the Federal Aviation Administration, a relationship the agency, after some not-so-subtle prodding by lawmakers, is beginning to change.

The nation's air carriers have been struggling for months to cope with stratospheric fuel prices. Those costs helped push ATA Airlines into bankruptcy court on Thursday and prompted Aloha Airlines to halt operations.

Houston-based Continental Airlines has been spending $170 a second on jet fuel, the company said, and a $1 move in the price of a barrel of jet fuel over a year's time causes the carrier's annual expenses to swing by $45 million. At the same time, the nation's carriers in the last few weeks have parked at least 565 aircraft because of maintenance concerns.

But a string of witnesses testifying before the House Transportation and Infrastructure Committee tied those groundings to the investigation of the FAA's handling of a safety lapse at Dallas-based Southwest — not to the industry's economic challenges.

In March 2007, for example, FAA safety inspector Charalambe "Bobby" Boutris learned that an agency supervisor had permitted Southwest to continue flying Boeing 737s despite cracks being discovered in a fuselage. Eventually, Southwest officials learned 46 aircraft were overdue for inspections of their fuselages, and their subsequent inspections found cracks in the fuselages of six.

Southwest continued to fly those aircraft for nine days after formally notifying the FAA that it was late in conducting these inspections, according to the testimony.

U.S. Department of Transportation Inspector General Calvin Scovel III estimates 6 million passengers flew on those jetliners after they should have been inspected, and 145,000 rode on them after cracks had been discovered on one.

Boutris and other witnesses testified to what they described as a cozy relationship between FAA and Southwest, a conclusion supported by the Inspector General's report.

"We found that FAA's Southwest inspection office developed an overly collaborative relationship with the air carrier," Scovel told lawmakers.

And more broadly, the inspector general raised questions about whether the FAA promoted "a pattern of excessive leniency at the expense of effective oversight."

Boutris argued that relationship developed, in part, because of the FAA's attitude that the airlines are the agency's "customers," an approach Nicholas Sabatini, the FAA's associate administrator for aviation safety, insisted was not what senior management intended.

Boutris and other FAA officials who raised concerns about the FAA's handling of the Southwest problems told lawmakers that they were harassed for pressing their concerns.

Boutris was pulled off his responsibilities for Southwest for five months. Michael Mills, now the FAA's assistant manager for the Dallas-Fort Worth Flight Standards District Office, told lawmakers he was "abruptly removed" from his job as manager of the Southwest Airlines Certificate Management Office.

Safety inspector Douglas Peters told how a supervisor picked up a picture of his family and said, "You have a good job here, and your wife has a good job" at another FAA office.

"I'd hate to see you jeopardize your careers."

Eventually, Boutris and Peters forwarded their concerns to the Office of the Special Counsel, which handles whistle-blower complaints. Both the Inspector General's office and the Transportation Committee launched investigations.

The FAA launched an enforcement action against Southwest in November.

On March 6, nearly a year after the Southwest fuselage cracks were discovered and six days before the Transportation Committee was scheduled to hold its hearing, the FAA slapped Southwest with a $10.2 million fine for operating the 46 aircraft without per-forming the mandatory inspections.

Scott Bloch, head of the Office of the Special Counsel, argued that the FAA was "covering up its wrongdoing and trying to get ahead of the story by leading the public to believe a deception — that Southwest, and Southwest alone, was to blame."

"It levied a record $10.2 million fine and caused a large hoopla all to shift the blame from the FAA to the airlines," Bloch told lawmakers Thursday.

On March 18, the FAA launched a special two-week inspection of the carrier's maintenance programs. And soon Southwest, United, American and Delta airlines were parking aircraft because of maintenance concerns.

Asked whether FAA had been doing its job, Boutris noted: "Why do we have these hundreds of airplanes being taken out of service?"