Well, this is an issue that I've wanted to address for a while now. At the top of our fly tower, there are three smoke hatches that are original to the building and likely installed in 1965/66. They're quite large, much larger than any I've seen in my research. They were made by Bilco and installed with winches at deck level so they can be opened for testing, or ventilation and daylight. Until recently, we haven't had a crank to open them, but at the end of last school year I made one just to see if they worked. As I feared, when I loosened the cable, it just went slack and the hatch stayed shut. It opened when I pushed it from the genie, with a couple of pounds resistance, but did not spring open. Each hatch has three gas springs that look identical to automotive shocks (made by maremont/gabriel), which I assume have lost their springiness after 46 years. Needless to say, if there's a fire and the fusible links melt they will not open. Maremont/Gabriel seems to be defunct now, and it doesn't appear that Bilco makes this type of hatch anymore.
So what do you suggest we do about this?
The device in question:
The hatch itself: