Was it the unique ice, crew issue, or an aircraft design flaw? Explain the findings and principles.Many events led up to this crash. There wasn’t one particular reason why American Eagle Flight 4184 crashed. Several causes were contributing factors in this accident. The majority of the findings addressed inadequate icing certification regulations, the lack of certification oversight by the FAA and/or DGAC, insufficient bilateral communication during certification of boththe ATR-42 and -72, and inadequate flight crew information on aileron hinge moment reversals and recovery techniques. This aircraft crashed during descent after uncommanded roll excursions and a loss of control. Prior to the approach into Chicago, Illinois (ORD), the airplane was in a holding pattern inicing conditions, and it was descending with the autopilot engaged to a newly assigned altitude of 8,000 feet when an uncommanded roll excursion occurred. The initial roll excursion and subsequent loss of control were precipitated by an airflow separation forward of the ailerons and an uncommanded aileron deflection resulting from an aileron hinge moment anomaly. The airplane was destroyed by impact forces, and all the occupantsreceived fatal injuries.