Airline passengers endured more than 700 flight cancellations in two days this week and could be faced with more during a Federal Aviation Administration crackdown on the nation's airlines.

American Airlines and Delta Air Lines canceled the flights to check wiring on planes in the wake of an FAA directive 10 days ago that ordered all U.S. airlines to check their maintenance records for safety problems.

American repaired wiring on 145 of 291 airplanes it inspected, airline spokesman Tim Wagner said. None of the 177 planes that Delta checked needed repair, spokeswoman Betsy Talton said.

American said its cancellations disrupted 46,000 passengers, many of whom got on other flights.

Other airlines said they don't have any immediate plans to cancel flights, but that could change as the FAA broadens a safety inquiry launched after Southwest Airlines was fined a record $10.2 million earlier this month. The FAA said Southwest had flown airplanes after failing to inspect the planes for cracks in the skin.

"I wouldn't be surprised if in the next weeks, you saw other carriers pulling planes out of service," said Dick Marchi, senior vice president of the Airports Council International. With flights running at record capacity, "that has the potential to be very disruptive," Marchi added.

Airlines said they will not hesitate to cancel flights. "There is nothing an airline does that is more important than safety. If that means canceling flights, they will do that," said David Castelveter of the Air Transport Association, which represents major U.S. airlines. "Carriers (are) under enormous pressure by regulators, Congress and the general public to ensure that they are in compliance" with safety directives.

Airplanes are being pulled out of service and into hangars as the FAA reviews whether airlines have followed detailed maintenance orders known as "airworthiness directives." The FAA issues dozens of directives each month, instructing airlines on how to maintain planes.

The FAA launched a review March 18 of all airlines' maintenance practices to see if they followed safety orders.

"So far we're seeing a high degree of compliance," FAA spokeswoman Alison Duquette said. Results of a preliminary inquiry, which ends today, will be known next week. A broader review will run through June 30.

Meanwhile, the FAA itself has been called into question. The House of Representatives transportation committee plans a hearing next week into what it called "critical lapses" in FAA oversight of plane maintenance.

The FAA has acknowledged that its inspectors did not adequately check on Southwest to make sure its planes had been properly inspected. Two FAA whistle-blowers have alleged to the House committee that FAA managers allowed Southwest to violate the rules.