Incident Details
During cruise, the flight crew discovered they could not move the control wheel for lateral (aileron) control. The rudder and elevator flight controls remained free. As the flight neared its destination, the crew attempted to extend the wing flaps. The leading edge slats extended, but the trailing edge flaps could not be extended. The flight landed in that condition.
Post-Flight Examination
Post-flight examination of the airplane revealed ice accumulations in all three wheel wells. The ice had accumulated on the aileron control cables and flap extension cables, preventing cable movement.
Water Leak Origin
The ice was traced to a water leak in the potable water system. A rubber hose attached to a water line fitting under the floorboard near the 3R door was leaking. When the floorboard in the area was lifted, upward movement was restricted by the rubber hose water line attached to the underside of the floorboard. Water was observed misting from the line where it attached to the fitting. When the floorboard was lifted further, the water line pulled loose from the fitting, and water flowed out. Examination of the rubber water hose revealed its failure was due to excessive load applied to the crimped joint between the flexible hose and its end fitting.
Maintenance Issues
The airplane manufacturer had attached water lines to the underside of floorboards. The airplane maintenance manuals did not contain any information about how to know if a water line was connected to the underside of a floorboard, or for disconnecting water lines attached to the underside of floorboards prior to lifting them. There was no jammed flight control checklist in effect at the time of the incident. QAR data revealed the pilots had limited movement of the ailerons with the autopilot engaged or disengaged through roll control wheel steering (RCWS), a customer selected option for the airplane.