US FAA ordered Bombardier to correct potential flap failures on some 684 CRJ100s/200s operated in the US by Air Wisconsin, Atlantic Southeast Airlines and SkyWest Airlines.

"The Bombardier CL-600-2B19 airplanes have had a history of flap failures at various positions for several years," the agency said. "Flap failure may result in a significant increase in required landing distances and higher fuel consumption than planned during a diversion." Thus far, no fatal accidents have been attributed to flap failures.

The directive requires a revision of the airplane flight manual to incorporate procedures to address flap failures. It also requires training for the operational procedures, cleaning and lubricating flexible shafts and installation of metallic seals in the flexible drive shafts.

Bombardier was given 30-120 days from Sept. 5 to make the required changes. Transport Canada officials issued a similar safety directive last month, the Associated Press reported.