DCA95MA001

The airplane was in a holding pattern and was descending to a newly assigned altitude of 8,000 feet when it experienced an uncommanded roll excursion and crashed during a rapid descent. The loss of ccontrol was attributed to a sudden and unexpected aileron hinge moment reversal that occurred after a ridge of ice accreted beyond the deice boots. The manufacturer failed to disseminate adequate warnings and guidance to operators about the adverse characteristics of, and techniques to recover from, ice-induced aileron hinge moment reversal events; and failed to develop additional airplane modifications, which led directly to this accident. The DGAC failed to require the manufacturer to take additional corrective actions, such as performing additional icing tests, issuing more specific warnings regarding the aileron hinge moment reversal phenomenon, developing additional airplane modifications, and providing specific guidance on the recovery from a hinge moment reversal, which led directly to this accident. The ability of the FAA to to monitor, on a real-time basis, the continued airworthiness of the ATR airplanes was hampered by the inadequately defined lines of communication, the inadequate means for the FAA to retrieve pertinent information, and the DGAC's failure to provide the FAA with critical airworthiness information., because of the DGAC's apparent belief that the information was not required to be provided under the terms of the Bilateral Airworthiness Agreement.

On Monday, October 31, 1994, about 1600 CST, an Avions de Transport Regional ATR-72, N401AM, operated by Simmons Airlines as American Eagle flight 4184, struck the ground after the flightcrew lost control of the airplane during an adverse roll event at 9,200 feet. The captain, first officer, two flight attendants and 64 passengers received fatal injuries and the airplane was destroyed by impact forces. The instrument meteorological conditions (IMC) prevailed, both en-route and at the accident site; and an instrument flight rules flight plan had been filed. Flight 4184 was being operated under 14 CFR Part 121 at the time of the accident.

American Eagle flight 4184 was scheduled passenger service between Indianapolis, Indiana and Chicago, Illinois. The flight had proceeded uneventfully until it arrived in the Chicago area, where the flightcrew was instructed to "hold" for sequencing into Chicago's O'Hare Airport (ORD). Flight 4184 had been holding for approximately 32 minutes at 10,000 when the crew received a clearance to descend to 8,000 feet. During the descent to 8,000 feet and in a right turn in the holding pattern, the airplane rolled to approximately 70 degrees right wing down. The flightcrew attempted to recover, however, the airplane rolled to the right a second time and continued to roll to an inverted position.