Flap over MU-2 Flap Goes Away

Owners of some 360 U.S.-registered Mitsubishi MU-2Bs won’t be required to install newly designed flap torque-tube joints, as proposed last September. Operators have been required to perform repetitive inspections of the joints under an AD issued in 1988, and the FAA found that there have been no service difficulty reports indicating cracks in joints for current design parts since that directive. The cost of installing an improved-design part is estimated at more than $25,000 per airplane. There is one fatal accident on record in which improper reinstallation of the cotter pins in the torque tube after one of the required inspections resulted in a disconnect, causing asymmetric flap deployment during a landing.