Sadly, nylon too grows brittle with age, though some use it for brake lines.
Yes, it will, but if you use black it lasts far longer. It's UV resistant, as it has to be when it's used on truck air brake systems. Those trucks have nylon tubing all along the frames and coiled nylon hoses between the tractor and trailer, out in the sun all day for years at a time, and those aren't even black. They're green and red, for service and emergency lines. If a nylon hose rubs up against the frame rail it will get dirt embedded in it and cut into the rail. Saw that in the 70s shortly after nylon replaced copper on trucks. It's tough stuff. On my airplane, as I said I had it for over 20 years without any failure and it was still supple when I sold the airplane. The airplane was hangared, though, for 16 years and out in the sun for another five.
Rubber hoses also suffer from the elements. The fabric deteriorates in the sun and rain and dirt. The steel braid starts rusting. The rubber hardens with age, chemical attack and ozone. I rebuilt over 50 hoses on a single transport-category airplane and found all of that. Some of them were as hard as wood. Most were seeping oil.
Aluminum lines corrode and will fatigue if asked to flex repeatedly. They are subject to abrasion and mechanical damage if not protected.
There are no perfect systems. One uses what he has to. For certificated airplanes you use what's specified in the parts manual. For homebuilts you can use other stuff; you're the builder and test pilot. I used nylon tubing because it was inexpensive and light and compact and I was VERY familiar with it, having been a shop foreman in an air brake remanufacturing shop for 12 years. I used that stuff in numerous production and test machines I designed and built for the plant. WHen I used it for brake tubing I checked it at each annual and found no reason to replace it.
I plumbed our new house for a basement bathroom. I used PEX, as the builders had used everywhere else. Half-inch PEX is rated at around 160 PSI at room temperature. I was concerned about the fitting attachments, since the fittings only have a couple of tiny ribs to grip the tubing and the clamp ring holds it all together. I took a foot of that PEX and clamped a PEX plug in one end and an NPT fiitting in the other. Took it to work at the airport and filled it with 5606 and connected it to the hose tester. Covered it well with rags. Pumped the pressure up. At 910 PSI it blew. The tubing had swelled and split; the fittings hadn't moved. Showed the inspector what I'd done and he took it back to the office to show the other guys. They had also wondered what pressure that stuff was good for.
PEX's rating drops with hot water. I didn't test it hot.
Edit: I should also point out that the tubing many call nylon is not nylon. A lot of tubing is polyethylene or vinyl, and those suffer worse with age and UV and chemical attack that nylon does. They also won't take high pressures. I've seen those plastics deteriorate fairly rapidy with fuel in them. I wouldn't even use nylon for fuel. Even the low- and medium-pressure hoses approved for fuel in certificated airplanes are normally recommended for replacement every five years.
