Must an instrument approach plate be visible during the approach? Is there any legal requirement to display the approach plate for an IFR approach? Typically it's briefed as part of the descent checks and then kept on display - but I'm struggling to find any legal requirement to keep it visible.
If you can't find any language for that sort of thing there probably isn't any.  At some point the value of regulations ends and you have to let common sense and good airmanship prevail.