While traveling straight down a gravel driveway the front passenger control arm broke causing the wheel to collapse and fold up under the vehicle. the vehicle was traveling at approximately 15 mph. the driver noticed loss of steering and then an abrupt stop. there were no signs that anything was wrong with the vehicle before the incident occured. the vehicle did not strike anything to cause the damage. the driveway was in good condition and there was nothing unusually that would have caused this type of failure. no one was hurt in the incident. the fracture in the control arm shows signs of cracking (based on picture attached).