At the very beginning of Resident Evil 2 there will be a helicopter that crashes into the Raccoon City Police Department. While it does make for a cool story moment it also serves as roadblock of sorts later in the game. Once you’ve progressed to the point where you have made it to the roof area on the east side of the police station, you will run into a problem where you have to put out the fire to get back into the police station as a ladder has broken and left you stranded. This guide will quickly explain what you need to do here to put out the helicopter fire.
On the roof you’ll notice that there are water pipes running along the building. These pipes are broken above the burning helicopter wreckage. There’s also a pump on the wall near the ladder that you can interact with. Using the pump you will notice that it does make water come out of a pipe, just not the one you want. What you need to do is change the directional flow of the water.
You’ll need to head down the stairs behind you towards the boiler room area and flip the switch in the image below.
Watch out though. Once you flip that switch and try to move past the helicopter wreckage you will be greeted by a Tyrant who will continue to chase you until you’ve either shook him off your trail or injured him enough for him to stop chasing you.