What equipment failures have you seen underwater?

Sort of a spin off from another thread but what failures have you actually seen?

I actually saw my first serious gear failure the other weekend and it was a weird one.

I was doing a shallow water training dive off a tourist charter and a diver on the boat had her high pressure hose come off! After a torrent of bubbles and a quick air share and post shut down by the DM she was back on the boat no worse for wear all be it with a short dive.

Turns out the metal portion of the hose was corroded to the point that a simple tug to check pressure was enough to rip the hose off. Of course the corrosion was hidden by a stress reliever

All my failures have been of my own making LOL....stuff like forgetting to actually hook up the battery to my can light, or failing to turn my left post on after a valve drill and wondering why my inflator didn't work

I've seen a power inflator fail (an o ring broke or something) but it was caught during pre-dive checks because it made an annoying hissing sound when the first stage was pressurized.

Had a buddy with a leak in his LP hose...not a super fast leak, but enough to where we were at 90 ft and wondering why he was suddenly at 500psi! That was a rather quick ascent....

On my Air 2, it became separated, sort of at the top of the shoulder where the ziptie is. It's kind of hard to describe this - but the jist is that it would not inflate the BC because all the air was coming out at the shoulder. I was able to fix it underwater (always dive with a few zipties) and continue the dive. Once I got on the surface and back on the boat, I did a more proper repair - which enabled me to get a tighter pull on the ziptie than I could underwater.

Seen a few gear failures.

Mostly BC failures - the inflator mainly. Twice with my buddy it failed to inflate but he used drysuit as a backup and we continued the dives. A third time with him it was that it wouldn't stop inflating. He did about 15-20 dives with it that way before he had time to take it to the shop so would just vent his BC a lot. Another time I saw the BC bladder puncture in another diver (not sure exactly how this happened) but it was shortly into the descent so he just ascended and sat out the day's dives.

Saw a first stage freeflow - was told that this was due to poor maintenance later on, but do not know specifics.

Buddy's HP hose started leaking but the leak was slow so he kept diving until he got low on air, we were pretty shallow. He did burn through air very quickly though.

Another time I saw a tank o-ring fail under water. Was an OW student and it happened very shallow so they ascended straight away. Seen it happen a bunch on the surface but this was the only time I saw it under water.

Seen a few people lose weight belts, don't know if that counts as 'gear failure' though!

Only had gear fail twice on me. Firstly, after I jumped in my BC shoulder vent got locked open somehow and would keep venting. This was early on when I started diving so I was quite overweighted and had to swim hard to stay afloat. I was about to ditch my weight but my buddy managed to unjam the vent by wiggling it. The other time was my primary torch on a night dive. Batteries were relatively new so not sure what the go was. Replaced them and it has been fine since so must have gotten some dodgy batteries.

As a new diver at that time, I had a rental reg literally fall apart on me at about 35 ft.
We, My girlfriend and I where diving Monterey, Breakwater, and I took a nice cool breath of air, the next breath was nothing but water, I grabbed my secondary and then looked down, and in the sand laid all of the parts of my primary.

I have never rented gear sense this experience!

I once witnessed a first stage failure on a wreck dive at about 75 fts. One of the divers in our group (we were 5 divers) indicated OOA and our dive leader and my former instructor responded to him. Initially we thought that it was related to the tank valve but then on the surface found out that the first stage was the failure point. And yess, it was a rental reg.
The other frustrating experience, this time for me, was when I was leading a group. We dove at a small bay where you can see some antique sarcophagi on the bottom at 50ft. Having just arrived above the first sarcophagus I realized that the o-ring of our oldest member in the group was blown and he is usually a bit excited type. He was not aware of it and this helped me alot when we started our ascent. Fortunately at the beginning of the dive and at a considerably shallow depth and just below the boat it was not a big deal. But again rental equipment showed its disadvantages.

I've had a few minor inconveniences like my fins falling off (I now exclusively use spring straps & am quite spoiled to them).
My most serious was a cold water secondary regulator freeze- up & free flow whilst my primary was shut down. I'm not exactly sure why it free flowed, but I suspect that while I was using my left hand to pull my wings & tanks up to make the primary post shut down easier (I was stiff from the cold), I may have bumped the purge button with my left arm. This happened at 90 ft during a simulated emergency drill. I managed to breathe off the free flowing regulator while deciding how best to handle the situation & the instructor decided to take me to the surface to get things back under control.

I've had my reg Free flow. It was about 5 minutes into the dive. It wasn't a bad flow, but I returned to the surface. Upon inspection, the tech found that the Pressure seat had cracked in the first stage.

I've also had my BCD Inflator start to free flow into the BCD. I was not even under water when that happen so I of course aborted the dive. When they opened up the inflator there was a little grit in the valve that was keeping it from closing all the way.

I saw a brand new compass go berserk and that's about it in my 3,5 year diving experience.

Have my own gear since day one, and I take proper care of it...

Where to begin.....

Do you really mean "failures" or just problems? Sometimes they're hard to tell apart. These are ones I remember witnessing first hand.

Regulator:
- mouthpiece separated from 2nd stage
- 2nd stage failure due to sand caked inside the housing that only came loose during the dive (rental gear)
- Temporary 2nd stage failure do to the exhaust valve being either folded over or otherwise blocked open by debris.
- LP hose failure
- 1st stage DIN connect separation causing the entire 1st stage to come loose and allow gas from the tank to free flow straight into the water.
- 1st stage INT connect separation causing the same as above.
- many different kinds of leaks from HP hose leaks to SPG coupling leaks to slight 2nd stage free flows to uncontrolable 1st and 2nd stage freezes in extremely cold weather (although this happend on the surface)

BCD:
- Multiple inflator hose breaks and separations, usually caused by pull-to-dump
- Power inflator freezing (acutally more likely than a regulator freeze in cold water).
- Backpack separation from the main body of the BCD causing the tank to float up over head
- leaking due to disintegration of the bladder (yes it was old).

Tanks:
- many o-ring failures both above and under water.
- valve knob separation during valve drills.
- valve knob threads stripped and tank stuck in open position after the dive
- tank slipping out of the cam band

Misc:
- Mask strap breakage
- fin strap breakage, including one case of a spring strap pin falling out
- dry suit zipper failure causing leakage
- dry gloves becoming uncoupled under water and leaking
- dry gloves being "cut open" by a line under water in 2c water during a training dive for ice (very painful)
- dry suit inflator free flow
- dry suit inflator freeze
- dry suit exhaust vent blocked inside the suit by the neoprene flap under the zipper being folded the wrong way
- dry suit exhaust valve leaking and causing the diver to get very wet. also many other examples of wet drysuit dives.
- computer failure
- computer giving false depth readings
- analogue depth gauge giving false depth readings
- watch flooding
- light flooding
- bolt snap refusal to open when needed

hmmmmmm...... Well those are the ones I can remember either me or a buddy having off the top of my head. Probably 80% of those were avoidable with proper maintenance.

R..