1997-11-06: ACA 281 was on approach into Calgary after a flight from Regina, when the crew advised ATC of an unsafe flap indication. The crew declared an emergency and requested vectoring to an area where the crew could work on solving the problem. The crew were then vectored back to the airport and landed on Runway 28 at 2140Z without further incident. It is unknown at this point if the flap problem was corrected prior to landing. UPDATE Maintenance changed the right outboard BPSU,
and in the process found water in the flex shaft. The flap drive power unit (PDU) was replaced and the left and right flex drives were disassembled, cleaned and lubricated. The flap system was re-rigged as per the maintenance manual. The FECU
was interrogated and a functional test of the flap system was completed without further incident.