NEVER!

I pull them out of the bag and put fuel in them even before they get installed and shake them and roll them in all directions. One of the biggest unknowns in turbines is "How did that bubble get through the UAT?" Usually it's because the air was not properly purged to begin with. If the UAT is empty it is either because the bird is out of fuel or it has augered in...............

Tailwinds,

John