UPDATE 1-FAA to check safety compliance at all US airlines

(Details of FAA order, airline response)

By John Crawley

WASHINGTON, March 18 (Reuters) - U.S. aviation inspectors were ordered on Tuesday to review maintenance records at all domestic airlines to ensure that carriers have complied with safety orders and other directives.

The unprecedented audit by the Federal Aviation Administration (FAA), which is under pressure from Congress to tighten oversight, stems from alleged inspection lapses at Southwest Airlines (LCC.N) that led the agency to propose a record fine of $10.2 million on March 6.

Over the next three months, the FAA wants a snapshot of compliance with an array of safety directives issued over the years that required inspections or other maintenance work. Part of the mandatory review targets the older model Boeing Co (BA.N) 737s, which were at the center of the Southwest controversy over checks for structural cracks caused by metal fatigue.

There are several hundred older 737s in the world fleet, many of them with U.S. airlines that are phasing out the least efficient models. There are 4,000 jetliners of all types flown by domestic passenger airlines and another 2,800 planes flown by regional carriers, FAA statistics show.

Regulators do not suspect there are inspection oversight problems at other airlines similar to those uncovered at Southwest, but they believe a broader review makes sense.

"One carrier's noncompliance with (safety directives) makes it necessary for us to validate our system for overseeing your management of this regulatory requirement," FAA safety chief Nicholas Sabatini said in an e-mail to airlines.

Major U.S. airlines, through their trade group, said the FAA acted prudently.

The FAA issues hundreds of safety directives each year. Some require simple checks while others mandate expensive fixes. In rare cases, planes are grounded.

Southwest allegedly missed deadlines to inspect 46 Boeing Co (BA.N) 737 aircraft for structural flaws in 2006-07 and flew those planes after alerting the FAA about the oversight but before it completed the checks. Small fuselage cracks were found on six planes and fixed.

Southwest said it consulted the FAA and Boeing on the matter and thought it had satisfactorily resolved the compliance issue months ago. Two FAA officials in Dallas have been reassigned and three Southwest employees have been suspended over the incident.

Southwest subsequently launched an internal review of its records and found another lapsed inspection for fuselage cracks. It immediately grounded 38 planes last week. Four were found to have cracks, the airline said.

The FAA action announced on Tuesday will require airlines with older 737s, such as some of the aircraft flown by Southwest, to produce inspection records for structural cracks. Other than the 737 mandate, FAA inspectors are free to select which directives to review at each airline.

Inspectors must validate that airlines followed proper procedures when addressing a directive and should take "immediate corrective action" if there is evidence of non compliance. Planes could be grounded if certain problems are found, the FAA said.

The agency wants an initial report from the field by the end of the month and a more complete set of findings by the end of June. The goal is for inspectors to eventually cover compliance rates for 10 percent of the U.S. fleet.

Congress has in recent weeks been sharply critical of FAA oversight and is planning hearings next month. The House of Representatives Transportation Committee, which triggered the investigation of Southwest that led to the fine, is now looking into the potential for similar problems at other airlines. (Reporting by John Crawley; Editing by Brian Moss/Andre Grenon)