I worked three decades in aerospace and you would think this would be simple to follow procedures. I can attest that it is anything but. Especially with vac fill procedures. We had one piece of space hardware that we made a rotation fixture to reorientate the hardware as we did the oil filling after pulling a hard vacuum. Was amazing to watch the air bubbles appear after working them through the maze of plumbing.
edit: many mistakes are made from rushing the procedure. takes time.
