CHICAGO, Illinois (CNN) -- United Airlines canceled 31 flights Wednesday in order to test fire suppression systems on a number of Boeing 777 aircraft, after discovering a routine check had not been done.
United Airlines spokeswoman Megan McCarthy said Wednesday the company had completed testing on 14 of its 52 Boeing 777 aircraft, and expected to test the remaining aircraft within the next day or so.
Through a regular review of maintenance records, United discovered that the "functional test" on the firing system on one of the five bottles of the cargo fire suppression system in all of its Boeing 777 aircraft had not been conducted, the airline said.
The company contacted the Federal Aviation Administration to inform the agency of the situation, McCarthy said.
United's Boeing 777 aircraft typically complete 84 flights daily, she said.
The company's announcement came two days after it said it had found faulty wiring in the landing gear of three of its Airbus A320 planes, which United Airlines and government officials believe caused a pair of nonfatal runway accidents.
United said it informed its employees of the incidents "and the corrective steps we are taking."
"We further conducted a stringent review process with our maintenance partners to ensure they had the same information," it said.
One of the planes skidded off a runway while landing at Jackson Hole Airport in Wyoming in February, McCarthy said. There were no injuries.
Another plane briefly veered off a runway at Chicago O'Hare International Airport in October 2007, she said. Two people had minor injuries as a result.
Both accidents were reported to the National Transportation Safety Board. The faulty wiring was mentioned in an initial NTSB investigative report of the February incident, on the agency's Web site.
"Examination of the left main landing gear brake system revealed that the inboard and outboard wheel speed tachometer wires were cross-connected," the report stated.
Faulty wiring such as that could cause the plane to skid, the report concluded.
Last week, Delta Air Lines and American Airlines canceled hundreds of flights so the companies could conduct inspections on certain bundles of wires in some of their jets.
Those inspections were prompted by questions raised by the FAA and American Airlines safety officials about how those bundles are secured in MD-80 series aircraft.
Three weeks ago, Southwest Airlines grounded about 44 of its Boeing 737s after a CNN report said the company had continued to fly more than 100 aircraft without certain mandatory safety inspections. The CNN report, which cited detailed congressional documents, stated that Southwest airplanes flew planes without conducting mandatory checks for fuselage cracking.
Southwest placed three employees on administrative leave after the incident and conducted an internal investigation into the allegations.
Most of the planes were returned to service after they were deemed safe, Southwest officials said. E-mail to a friend
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