The FAA today approved a plan that would require Southwest Airlines to replace unapproved parts installed on about 50 Boeing 737s–roughly 10 percent of its fleet–and for the aircraft to undergo inspections until the airline completes the fixes. The airline already has replaced parts on 30 other airplanes.

An FAA technical review has determined that the unapproved part would not prevent safe operation of the airplanes. The aircraft manufacturer has made a similar determination. As a result, the FAA has determined that the airline may continue to operate aircraft with the unapproved part until the parts can be replaced, on the condition that each airplane must undergo physical inspection for wear every seven days and that Southwest must replace the affected parts–associated with hinge fittings for the exhaust gate assembly, designed to protect the wing flaps from hot engine exhaust–with approved parts by December 24.

The FAA has also directed Southwest to locate and dispose of any other unapproved parts made by the same vendor and to report on the results of its aircraft inspections to the FAA on a daily basis.

The FAA determined on August 21 that the parts had been installed on 82 Southwest Airlines airplanes. The agency has opened an investigation into the issue.