A blowout is when the well bore pressures exceed the hydrostatic pressures of the fluid in the well bore. Then the pressure starts pushing the fluid out of the hole and you have a full blown blowout. Hopefully when that happens you have had the proper well control training and you can close the blow out preventer. Therefore stopping the blowout. I have been working with blowout preventers for 30 some odd years now and if I have to put one on my heli I am gonna be mad. LOL. Thought I would throw a little humor at you guys and watch out for them blowouts they will get ya. The last one I had took out a Drilling Rig and lost a really good well. Happy Flying Guys.