Narrative:

Climbing through FL250, we received an autoplt trim caution message with a boxed 'a' on the pfd. Upon turning off the autoplt, we noticed that the ailerons were stiff but we could still make turns. We contacted dispatch, maintenance, and notified ATC and declared an emergency. Descending through 15000 ft, while hand flying, I made a slight turn and could feel it release. At that time all controls were working normally. We landed uneventfully at ZZZ maintenance believes the problem was icing of the aileron controls from moisture that was picked up during the takeoff phase. If this was the cause, an engineering team needs to address the issue. Until then, pilot awareness of this issue could be increased, and changes in the definitions of contaminated and wet runways a must. Callback conversation with reporter revealed the following information: the reporter stated this aileron stiffness or binding is the subject of an airworthiness directive and is a recurring problem with this airplane. The reporter said when this airplane is taken off or flown through moisture, the aileron controls are prone to freezing, stiffening or binding. The reporter stated when this airplane was on the ground, an engineering team investigated the aileron control system. Callback conversation with reporter acn 577578 revealed the following information: the reporter stated the airplane aileron system is the subject of an airworthiness directive and requires that crews, if flying into moisture, must make small 5 degree banks and turns to keep the ailerons free. The reporter said the aileron controls became free after descending through 15000 ft. The reporter stated this was his first experience with stiff or binding ailerons on this airplane but is aware of the problem.

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Original NASA ASRS Text

Title: A CANADAIR CL65 CLBING THROUGH FL250 DECLARED AN EMER AND DIVERTED DUE TO DISCOVERY OF STIFF AILERONS AFTER AUTOPLT TRIM CAUTION.

Narrative: CLBING THROUGH FL250, WE RECEIVED AN AUTOPLT TRIM CAUTION MESSAGE WITH A BOXED 'A' ON THE PFD. UPON TURNING OFF THE AUTOPLT, WE NOTICED THAT THE AILERONS WERE STIFF BUT WE COULD STILL MAKE TURNS. WE CONTACTED DISPATCH, MAINT, AND NOTIFIED ATC AND DECLARED AN EMER. DSNDING THROUGH 15000 FT, WHILE HAND FLYING, I MADE A SLIGHT TURN AND COULD FEEL IT RELEASE. AT THAT TIME ALL CTLS WERE WORKING NORMALLY. WE LANDED UNEVENTFULLY AT ZZZ MAINT BELIEVES THE PROB WAS ICING OF THE AILERON CTLS FROM MOISTURE THAT WAS PICKED UP DURING THE TKOF PHASE. IF THIS WAS THE CAUSE, AN ENGINEERING TEAM NEEDS TO ADDRESS THE ISSUE. UNTIL THEN, PLT AWARENESS OF THIS ISSUE COULD BE INCREASED, AND CHANGES IN THE DEFINITIONS OF CONTAMINATED AND WET RWYS A MUST. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THIS AILERON STIFFNESS OR BINDING IS THE SUBJECT OF AN AIRWORTHINESS DIRECTIVE AND IS A RECURRING PROB WITH THIS AIRPLANE. THE RPTR SAID WHEN THIS AIRPLANE IS TAKEN OFF OR FLOWN THROUGH MOISTURE, THE AILERON CTLS ARE PRONE TO FREEZING, STIFFENING OR BINDING. THE RPTR STATED WHEN THIS AIRPLANE WAS ON THE GND, AN ENGINEERING TEAM INVESTIGATED THE AILERON CTL SYS. CALLBACK CONVERSATION WITH RPTR ACN 577578 REVEALED THE FOLLOWING INFO: THE RPTR STATED THE AIRPLANE AILERON SYS IS THE SUBJECT OF AN AIRWORTHINESS DIRECTIVE AND REQUIRES THAT CREWS, IF FLYING INTO MOISTURE, MUST MAKE SMALL 5 DEG BANKS AND TURNS TO KEEP THE AILERONS FREE. THE RPTR SAID THE AILERON CTLS BECAME FREE AFTER DSNDING THROUGH 15000 FT. THE RPTR STATED THIS WAS HIS FIRST EXPERIENCE WITH STIFF OR BINDING AILERONS ON THIS AIRPLANE BUT IS AWARE OF THE PROB.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.