Southwest Airlines Co., the largest U.S. low-fare carrier, has obtained approval from authorities to continue to fly planes with unauthorized parts before replacements are made by Christmas eve, reports said Wednesday.

The Texas-based airline said it reached an agreement with the U.S. Federal Aviation Administration (FAA) on Tuesday to extend the replacement schedule for certain exhaust gate assembly parts.

Replacements have been made on 43 of the 82 affected aircrafts, and the FAA is giving Southwest until Dec. 24 to replace unapproved parts on the remaining Boeing jets, Southwest spokeswoman Beth Barbin was quoted as saying by media reports.

Meanwhile, the FAA requested that Southwest examine the parts every seven days until authorized replacements are installed. The company was also ordered to locate, dispose of, and report any additional unapproved parts it finds.

The FAA began an inquiry after its investigators found on August 21 unapproved parts on 82 of Southwest's jets. The parts, designed to protect the flaps from getting burnt by the engines' exhaust, were manufactured by a company without FAA authorization for the work.

The FAA said Tuesday that the parts do not pose an immediate safety hazard. The jets' manufacturer, Boeing Co., drew the same conclusion.

The unauthorized parts refocused attention on Southwest's maintenance practices. In March, the carrier agreed to a 7.5 million-U.S.-dollar fine for flying aircraft without fuselage checks in 2006 and 2007.

The U.S. National Transportation Safety Board is also investigating an incident in July, when a football-size hole suddenly opened in the roof of a Southwest plane during flight, forcing an emergency landing.

(Xinhua News Agency September 3, 2009)