Currently in survival mode, while working at a power armor workbench, you will often take damage due to being over encumbered. This is caused by the weight of the armour attached to the PA frame being added to your inventory.
There are checks in the survival mode perks that should prevent the over encumbered effects from applying when working at a workbench, but they don't seem to work (using the CurrentFurnitureHasKeyword condition).
It may be related to CurrentFurnitureHasKeyword not working with PA workbenches, as the workbench is actually the power armour itself. The "hoist" just grabs the nearest PA and activates it. Or perhaps it's just that CurrentFurnitureHasKeyword doesn't work at all?
One possible <del>fix</del> workaround is increasing the players carry weight while using PA workbenches. Here's a fix I put together using this method which I'm using in my own game:
https://dl.dropboxusercontent.com/u/5641174/SurvivalPowerArmorEncumbranceFix.7z
Feel free to use it in the UFO4P if you want.