But Dervish, that is assuming they knew there was a problem before the incident, surely they can only be culpable if they did.
On the topic of nuts and bolts the snco plumber commented that the DAP says "tighten" and as far as he would be concerned that meant "tighten" properly.
Precisely, the term tighten means you would run the nut down the bolt until resistance is felt, you would not tighten a bolt and stop short of the shackle or short of when the nut becomes thread bound, the failing is in the terminology of what is required.
Everyone keeps mentioning shouldered bolts or introducing feeler gauges as the solution, well as we have discussed a shouldered bolt may or may not have strength or clearance issues, the simplest solution would have been to replace the existing bolt with one with a longer shank, thus retaining the diameter ( and strength ) of the current item but making it impossible to over tighten the nut or pinch the shackle by the simple fact the nut will become threadbound before it reaches that point.
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