My mtb has Avid BB 5 disk brakes. While reading up on these I came across a couple of reports of these brakes "giving out" and failing. Any truth to this? The reason I'm asking is the roads I ride here are veryhilly. One hill has about a 20-30% grade, if I'm correct. I would be in big trouble if I lost my brakes while going down this, or similar hills.
Am I safe with my BB 5's?

I don't know anything about BB5s, but I wouldn't worry terribly much unless you use your MTB for MTBing. I Highly doubt they'd both fail at the same time. If one gives out, the other should stop you just fine. Hell, we used to just jam a foot on the rear tire when I was a kid and that stopped us just fine.

^+1. Chances of both simultaneously giving out are slim to none, & if you're really worried (or just want to be prepared for worst case scenario--never a bad idea) then practice jamming a foot between the tire & seat stay in a controlled environment. Even if the unthinkable did happen & that last resort method locked up your rear wheel, it would still slow you down which is better than the alternative.

anybody know what to do about avid brakes that squeal when engaged? only the back on does this, really loud and annoying. I just changed the pads and bled the lines.

Avid BB 5's failing? There was a rumor running around several years ago about Hayes failing but I haven't heard anything about that in the last few years. Avid BB series have an excellent reputation. I have both the BB 5s and 7's and never had a hint of a failure problem. There's got to be a lot more on this forum that either have or had them. I can't recall anyone having a failure problem.

That said, there's always a first time. Have a nice day.

I've heard of the piston cracking in the caliper, but that was resolved 4 years ago...

Generally speaking, brake squealing is caused by contamination of pads or disk. If you had squealing and replaced the pads and still have squealing, I'd first think that your disk might have been contaminated and just recontaminated the new pad and the disk stayed contaminated itself. This would be evident by black rings on the disk. First step I personally would do is bake the pads in a preheated oven at 400 degrees for ~15 minutes or so and lightly sand the surface by rubbing the pad on the sand paper(on a flat surface) in a circular motion until the surface looks clean. Then do the same with the disks and then clean with isopropyl alcohol on a rag. You'll have to "bed in" the pads after that process. This is all assuming they aren't new brakes. If new brakes, you might just need to bed in the rear pads to quiet them down.

*never mind* nothing to see here

I have not personally experienced nor heard of a failure. I run BB5s on one bike, and a friend runs BB5s on his, and they work just fine for the sort of cross-country riding we do here in Michigan.

They are an entry-level, cross-country brake. Keep that in mind. If your goal is to do to mad-dash, multi-mile descents in mountain-country, then buy a suitable brake for that style of riding.

I had bb5's and both of mine failed. Not at the same time but about 6 months apart. This was back in 2009. The problem is a crappy spring inside the caliper which snaps. Unfortuantely the first failed after 1 and half years of purchase so no warranty claim.

Here's the pics I took.

Wow, That's the first time I've heard of a BB5 failing.