Southwest Airlines expects "minimal impact" in the coming days as the U.S. Federal Aviation Administration conducts overdue maintenance checks

on 128 of the carrier's Boeing 737-700 aircraft. Southwest on Tuesday canceled about 80 flights after removing the 128 aircraft—almost 20 percent of its fleet—from service upon discovery that a required maintenance check on their standby hydraulic systems was overdue. Since then, FAA gave Southwest approval to operate the aircraft for up to five days as the checks are conducted. The carrier expects the inspections will be completed within that period. Southwest also potentially faces fines from the error, "as the FAA generally takes these issues quite seriously," according to a research note from Cowen and Co.