There comes a time when venturing off road that leaf springs do fail. Your day of 4x4 fun comes to an abrupt end.
Such an occurrence recently happened to me. Luckily, the main leaf spring did not completely break and I was able to make it home after some scrounging and rigging a "splint" to keep the spring from flexing and completing the break.
Time for a little break analysis. For starters, the springs were new when installed with the spring-over lift in November and had seen 6 days of on the trail use. Springs are designed to flex and should offer trouble free action over an extended life. Spring failure can result from abnormal stress or metal weakness due to improper tempering.