Cracked frames are not uncommon. I found a spring hanger separating from the frame on my 2013 trailer about 1 1/2 years into ownership. The frame on my trailer (like most Rv trailer frames) was made by Lippert. I judged the causes for my trouble to be light weight low cost material (china metal
) and poor welding (too hot, undercut). Most RV repair dealers have seen this enough that they know how to repair and re-enforce the trailer.