The Flyer was torn down in 1992 , after it failed to meet safety standards.
That means nothing.
First of all, not meeting safety standard does not equate being unsafe. I have an engineer friend who once explained to me that safety standards are developed by using safety factors calculated on top of actual capacities. He called it the Ignorance Factor. For instance, you'll say" this beam can support a load of ten tons, + or - half a ton 99.99% of the time. So to make sure it won't break, we rate it at 9 tons, which is half a ton below the lowest expected failure point, but to this, you add a safety factor and voila, you are now just rated for 8 tons, just in case of an impossible outlier. Now, you do the same thing with the columns, and the braces, and the stringers, and suddenly, your bridge built to a capacity of say 100,000 tons won't fail even if you put 200,000 tons on it.
Also, second of all, you may fail to meet safety standards because they have been changed and it's too costly to modify to meet the new standards. That does not mean that the old standard was unsafe, just that the new one takes new matters in consideration and requires modification in order to be met.
Finally, you may fail to meet safety standards because, like everything else, your structure or system ages. Metal will rust (yes, even aluminum, we just call it something else), fatigue or wear down. It will not keep its strength forever and at some point has to be replaced or torn down. Similarly, wood putrefies and needs replacement. Concrete and mortars disintegrates over time and if cracked will be attacked by freeze and thaw cycles. Again, after a while, it does not meet the safety standard anymore and has to be redone.