CJ:
Here, we may be dealing with something that the engineers did not build in enough safety factors for... quite simply because the design was based on "the published limits" for the fuel itself.
I agree completely. I think they designers didn't consider very long flights across arctic airspace. The cold-soaking exacerbated the situation. I think it just happened that ice, slush, or whatever we want to call it caught on some protrusions in the piping and other components. At the risk of being slammed for repeating myself, it's time to start heating the fuel in the tanks before it has a chance to clog any downstream component. It's either that or limit the aircraft to warmer air and/or shorter flights in very cold conditions. The cost of retrofitting will be high but won't equal the cost of even one repeat accident.