10:50 Aug 15, 2015
"Hors état" is actually more or less a short form of the expression "hors état d'usage". An accurate rendering in EN will convey both ideas.
An element which is in poor condition is "en mauvais état". It is tending towards being "hors état", or may already be so.
A piece is "hors état" when it can no longer be used for its intended purpose as it is broken, in a poor state of repair, or damaged in some way or another.
A simple enough term on the face of it, but one with which you have to be careful.
If anyone reads this differently, then do go ahead and comment, disagree, or otherwise qualify, of course! | 
peer agreement (net): +6