On Friday, May 25, 2012 9:36:16 AM UTC-5, Bill D wrote:
On May 24, 11:05*pm, b4soaring wrote:
On Friday, 25 May 2012 03:54:00 UTC+1, son_of_flubber *wrote:

Also, CG hooks can back release if you get a lot of slack in the rope. The manual may suggest a method for blocking the back release - make sure you remove it before winching.

If the CG hook is functioning properly (i.e. no weak springs), it
would take a LOT of slack to get a back release. So much so that
you'd be in front of the tug and probably want to release anyway.
Don't mess with the hook or you might make it malfunction completely.

Uncommanded releases are not a problem.

Actually they very well can be. I was piloting an IS-28B2 Twin Lark a couple of years ago behind a Super Cub during a 175 km transfer aerotow to another airport. We had to go over a pass and coming over the pass flew straight into serious rotor off a sharp mountain ridge bordering the valley we were entering.

Keeping the glider in position behind the super cub was a handful (a Twin Lark flies a bit like tank depending on what you are used to), I did end up getting some serious slack at one point while perfectly pointed at the cub. The cable bow reached back (the bow being to the left and almost level with the glider) to about where I was sitting in the front seat of the glider when I heard the "clonk" of the back release, the very moment I was starting to get worried it might just do that while remembering that the back release was not blocked...

The Twin Lark has a non-structural nose cone and the aerotow hook mounted just in front of the front rudder pedals. It is the same Tost hook as the CG hook installed and hence back releases unless you do something about it...

I could have grabbed the released cable if it hadn't been for the canopy, it was right next to me before I banked away to avoid potential damage. The bow was never a danger to the glider and never went anywhere near the wing tip or something else it could have caught onto, so the back release was completely unwarranted in this scenario.

An uneventful outlanding in unfamiliar terrain followed since we had plenty of altitude and I had a variety of fields to choose from but it was an all-nighter to get the trailer and crew there, load up the glider in the dark and get it to the destination airport through some serious mountain roads.

I made sure with a metal angle blocking any backwards movement of the hook rim that this would not happen again...

Markus Graeber