I wasn't going to post this, but have been encouraged to by the guys on IRC.<p>
Metal fatigue is a sneeky bugger, you can't tell from looking at something that it's in imminent danger of failure - it just lets go (at the most inopportune time, of course!)<p>
Here's my story.<p>
Yesterday started out nicely. Calm, sunny and warm. By lunch time we had broken cloud, temperature was up around 38 deg C (almost 100F) but the wind was kicking up a bit. About 13:30 I was outside watching the turbine - the wind was gusting to 54kmh and the turbine was right on the edge of furling. Every time the wind swung towards the south, the turbine furled, tracked the wind and then took off again. Output was about 850 watts.<p>
While I was watching, the top guy on the windward side of the tower suddenly dropped to the ground!<p>
The tower lurched to the east and I BOLTED inside and applied the (electric) brake (shorts all 3 phases).<p>
With the turbine going at these speeds, it slowed the mill a bit but didn't really do much good.<p>
I grabbed a long rope and ran up top, planning to try to secure the thing somehow. But how to (safely) get a rope up there? I couldn't throw a rope that far up in this wind - and even if I did, it would be a fair bet I'd just get it caught in the prop and do untold damage.<p>
I quickly took one end of the rope and went around (over the top of) the remaining 3 guys and took the two ends back to the anchor of the (missing) guy and "walked" the rope up the other guys until it was at the top attachment point. Truckies knot and I was able to tension the rope enough to pull the tower back to straight and tie off the rope.<p>
Good thing, because shortly after, the storm kicked up a bit more - I only saw 81 kmh, but the official wind gust was 107kmh. The place opposite me lost its roof - it was ripped clean off at the top of the walls.<p>
There was a brief lull after that, when I ran up, attached the winch and lowered the tower. Upon inspection, it became obvious that it wasn't a guy failure at all, it was the half-inch steel rod the manufacturer had originally welded to the mast, which had let go.<p>
Here are some pictures (click thumnails for larger photos):
[img width= height=]http://house.albury.net.au/17dec2009/thumb.100_4039.JPG[/img]<p>
[img width= height=]http://house.albury.net.au/17dec2009/thumb.100_4041.JPG[/img]<p>
[img width= height=]http://house.albury.net.au/17dec2009/thumb.100_4042.JPG[/img]<p>
I'm pondering (unless anyone can give a good reason NOT to do this) - to re-string the guys, so each line comes up to the tower, in through the rebar loop, AROUND the tower, back out the loop - and then use the cable clamps to tie the two ends. This way, each guy will go completely around the mast.