Broken Steering lines

[cloud9 0]

I didn't know if this should go in safety or gear, anyway I'm here now.
Today I had an opening that started in a left spin, fairly fast. After two turns it stopped and slammed open. I looked up and saw the left steering lines were broken, I started into a slow left spin. ( which made no sense ) I reached up to grab the left toggle and it wasn't there. I was still in a left turn. I countered with right rear riser and had it flying straight. I looked up and saw a lot of lines broken, both steering lines so I flew over the pea area and chopped it. I had a great reserve opening and ride. Raven-m 218. So my question is what could make both steering lines break at the same time? I think my left turn was caused by lines wrapping and closing the end cells on the left side. But I can't figure out what could have caused both steering lines to break. We checked slider grommets and they looked fine, no other lines were hurt the canopy was ok. So if anyone has any idea's I would love to hear. I just can't think of how I could have packed that into that main. (Triathlon 175) loaded at 1.2 so a docile main at that.

[spectre230 0]

[cloud9 0]

The main has about 425 jumps and has never been relined. The lines appear in very good condition. Both steering lines broke about 20" below the cascade. Even the steering lines appeared to be in good shape. All other lines were not hurt on this jump. It seems real strange to me, and for that matter all the other folks that looked at it. Some of those having upwards of 3000 jumps. I sent it to a master rigger of course to see what he thought and for repairs. I just thought I would see if some of you experienced folks have ever seen this before and what might have caused it. Thanks for replying.