The dishwasher door falls pen quickly. I am guessing that the door hinge must be broken. How can I repair this? What is the typical life span of a dishwasher?
More likely is one or both of the door springs () has failed so now when the door is opened, you get to feel the full weight. A simple enough repair if you pull the unit from the cabinet, you can see where the springs connect. As for the life span, it all depends on when something gets to expensive to repair, or cannot be repaired due to part availability. I personally think the manufacturers are going for 5 years, but 12 seems to be a bit more likely based on cost and parts.
Thanks for your help! 
Glad I could help.