I had a front cross tube fail on a UH-1H during a normal landing several years ago while I was in the Army. They (Army) sent the parts to a lab and said that there was a small discontinuity in the tube wall and it failed due to fatigue.
The landing was an approach to the ground, the aft part of the skids touched down first and as the A/C rocked forward the front tube snapped at the support. There was no hard landing.