Where's Nigel to do his safety briefing bit?
OK - here goes.....
DO NOT be tempted to try and undo the top nut unless the springs are fully compressed (and the spring is loose from the top mount)
I had wound my springs a long way and I *thought* there wasn't much tension left in them, so I undid the top nut.
Thankfully, the strut was pointing away from me when it let go. There's still a mark in my carport wall where the top mount hit it. There's another mark in my neighbour's wall where the strut hit it. After all the big bits had stopped flying around the carport (thankfully didn't hit any cars or people), I glanced around for the top nut. A second or so later, I heard a faint clunk as the top nut hit the garden wall of the house on the other side of the road - a good 200 feet away. Given that it had taken so long to get there, I can only assume it had gone vertical when it came loose.
If any part of my anatomy had been in the way of any of the component parts of the strut, I probably wouldn't be here today. And don't forget, this was with the spring 90% compressed.
Dangerous things - treat them with respect.