balance,
The ATR had a problem with aileron reversal which was known at design phase to the engineers. They came up with a half fix in 1989 (VGs in front of the ailerons i think) but it was not sufficient to cover the lack of boot protection ahead of the ailerons. In icing conditions a ridge would form aft of the boots and disturb airflow over the ailerons agrevating the reversal problem. The NTSB and French Investigators blamed mostly poor pilot technique in icing prior to Roselawn and it was pilots who kicked up a fuss for years prior regarding the aircrafts unsafe tendancies in icing. Interesting that the engineers were still not listened to as they requested 23% of chord be covered by boots, I think they increased it to 17-18%.