thats what they get for using a material with no ultimate yield strenth.....

i would imagine fatigue over the years, like said above can only put 2 horses in a 2 horse trailer and 2 of my horses wiegh more than you can cram hay in it.

most of the newer higher end aluminum trailers use a steel tounge.

my 4star has a steel tounge thats huckbolted to the aluminum part of the trailer.

i had a featherlight gooseneck stock trailer break off right above the coupler and smash the back of the cab of my truck when i got in an accendent it stopped 6" behind my head in a crewcab truck. ill never own a featherlight again my 4star is 10x the trailer that one was.