On Wednesday, May 15, 2013 11:58:39 AM UTC-4, son_of_flubber wrote:
One of the lifting struts on my clam shell trailer lid is failing (partially or completely). It will not lock in the fully opened position so the lid sags down a few inches on that side. I suspect that the second strut is holding the entire weight. However, the lifting force required of my body to raise or lower the lid is symmetrical, so maybe both struts are providing some lifting force. Maybe the strut on the right has just lot the ability to "lock" in the fully extended position??



Yesterday I was assembling in gusty conditions. Both wings were on and when I turned around to get the horizontal stabilizer out of the trailer, I found that the lid had slowly closed. I'm trying to get two new struts ASAP and in the meantime I can live with a lid that slowly closes in gusty conditions.



What concerns me is the possibility that the lid will close suddenly and damage the lid, the glider or a person. Does this happen? Can a strut fail completely and suddenly, or is the deterioration gradual?



Maybe I should assemble the glider on a calm day and leave it tied out until I can replace the struts. Or maybe I should make some sort of brace from some 2X4's that will keep the lid from closing

What you're describing (gradual decrease in lifting force) is the typical failure mode I've seen. Note that it's also somewhat temperature dependent, so it's worse on cold days. I would definitely invest in a 2x4 or equivalent that you can jamb into the gap to temporarily backstop the struts. The real worry is that the clamshell comes down a little faster one day, just as you're pulling a wing or fuselage out.

P3