after prolonged rain the dried type/ii or iv fluid rehydrates, the aircraft then takes off and the gel freezes causing the control restrictions mentioned. The airline I work for had a number of problems at the end of the winter with virtually all of our 146/rj aircraft each aircraft took around 12 hours of constant flushing to remove all the remaining deice fluid residue from the aerodynamically dead areas, but touch wood we did not have this problem with the emb 145