I'm camp hosting in a state park and a camper with a Holiday Rambler came in with one completley broken and one cracked trailing arm. It is one of the nastier RV failures I've seen.
I did a little Googling and found out that Monaco products, including Beavers, with the Roadmaster R4R and R4RR suspensions have a high risk of trailing arm failure.
This is not new news. It was apparently reported in a FMCA magazine last fall. But I did a search here and didn't find anything on this forum.
My suggestion is that as we see and make friends with 4 bag Beaver owners at rallies, or other events, we ask them if they are aware of the risk.
There is a good description of the issues here:
http://www.rv-chassis.com/RoadmasterR4R_FMC1109.pdf