Hi Slekic,
I see this is your first post on this network. Welcome aboard. I defer to your age. Do you have technical background?
The leading edge devices on the 737 are powered by hydraulics. Hydraulic pressure is huge . Hydraulics will get the job done. Never get in the way of hydraulics !
You can study more here
http://www.b737.org.uk/flightcontrols.htm plus many other sites
Study is good.
This discussion is taking a technical direction now.
I like to study too but I am confused. I see from the photo, that the hole appears to be near the top of the fuel tank, and I believe (perhaps erroneously) that the fuel tanks are not pressurised. So how could so much fuel escape so quickly once the aircraft arrived in the parking position?