nut

Hi All, I know where the horn compressor and tank is, however, it appears the tubing going to the horn may have a leak. Question: Do you know which panel (ceiling) would need to be removed to get at the nut holding the horn in place?

I have a 2000 340, and had props reconditioned. I'm wondering best way to get a good amount of torque on the nuts. The tunnel is tough to wedge a block of wood against blade, and im not sure the prop would take the force? I read its not the way to go. But, how else can I get 200lbs of torque by...