I'm not going to challenge DJPil. He's forgotten more than I know.
But my point was kind of that CASA have never cared what clipboards, charts, notebooks, timers, reading lights, checklists, push to talk switches, pencil hoders, pencils, etc get attached to control columns. In fact, I would suggest that you would be in trouble for an MECIR review without a control mounted chart clipboard.
Its a bit precious now to get bent out of shape about 298g for an iPad mini plus 100gm for a RAM x-grip, 100 gram for an extention and 135g for a yoke mount = 633g.
If its unsafe to add this weight of iPad, its also unsafe to add this weight of paper, pens & checklists. CASA are using the introduction of new technology as a power grab.
And for the guy talking about Beech & throwover columns. Have you ever seen the stuff they make to attach to them???? It stops just short of a coffee machine.