Southwest back to normal operations

(CNN) -- Southwest Airlines said it resumed normal operations Thursday after several dozen planes were reinspected on Wednesday.

"We had a normal launch today," Linda Rutherford, a Southwest (LUV, Fortune 500) vice president for public relations and community affairs, said in a statement to CNN.

There were three cancellations Thursday unrelated to the inspections.

The company pulled 44 planes from service for inspection after an "ambiguity related to required testing" was found during a review of records, the airline said Wednesday.

The 44 aircraft included five that were already out of service for scheduled maintenance checks, plus one that "was already retired," the company said.

Taking the other 38 planes out of service resulted in the cancellation of "approximately 4% of today's Southwest flights" on Wednesday, the release said.

But good weather conditions helped minimize the schedule disruptions, Southwest said, and flights ran more than 90% on time Wednesday.

The company said in its statement it expected to complete the inspections of all 38 aircraft by Wednesday night.

But it said other such service interruptions could occur in coming days because of "the ongoing internal review of Southwest's maintenance programs, policies, and procedures."

Neither the release nor Southwest spokeswoman Whitney Eichinger said whether the inspections were of the plane's fuselages or rudders, both of which were part of a CNN exclusive investigation released last week.

The House Transportation and Infrastructure Committee issued a statement on Southwest's decision to ground the 38 planes.

"This action by Southwest Airlines raises serious questions about whether [the Federal Aviation Administration] adequately followed up on the discovery a year ago that Southwest had failed to make required inspections," the statement said. "FAA should have immediately undertaken a review of the airline's records to see whether Southwest had conducted all required inspections, and whether procedures were in place to ensure timely inspections in the future.

"Had such a review been conducted, FAA would have found or prevented the 'ambiguity' in Southwest's maintenance which Southwest has discovered after its own review of its records this week."

Violation of safety checks. According to detailed congressional documents obtained by CNN, Southwest Airlines flew some planes in violation of mandatory safety checks. Last week the FAA initiated actions to seek a $10.2 million civil penalty against the airline for allegedly operating 46 airplanes without conducting mandatory checks for fuselage cracking.

Rutherford said the inspections take about 90 minutes.

Earlier this week, Southwest placed three employees on administrative leave and began conducting an internal investigation into the allegations that it flew planes without proper inspections.

"Upon learning last month of an investigation with respect to our handling of this inspection and an airworthiness directive, I immediately ordered an independent and comprehensive investigation by outside counsel," Southwest Airlines CEO Gary Kelly said in a statement released Tuesday.

CNN's Drew Griffin contributed to this report.