 On one customer-acceptance flight, where the yaw damper was turned off to familiarize the new pilots with flying techniques, a trainee pilot's actions violently exacerbated the Dutch roll motion and caused three of the four engines to be torn from the wings.The plane, a brand new 707-227, "N7071", destined for Braniff, crash-landed on a river bed north of Seattle at Arlington, Washington, killing four of the eight occupants.In his autobiography, test pilot Tex Johnston describes a Dutch roll incident he experienced as a passenger on an early commercial 707 flight.