Yeah, two hands if the chuck is in two sections. From a manual:
Keyless Single Sleeve Chuck (Fig. 6–8)
WARNING: Do not attempt to tighten drill bits (or any other
accessory)
by gripping the front part of the chuck and turning the
tool on. Damage to the chuck and personal injury may result. Always
lock off trigger switch and disconnect tool from power source when
changing accessories.
I'm sure we all do this to snug the bit and to change the chuck openings for different size shanks but, hand twisting to tighten and to loosen is the rule. Your drill motor doesn't like being used to final-tighten or unlock the bit any more than it likes being ground to a halt under power. Its hard on the tool. I know we all see folks do this on a regular basis. These may also be the folks that complain about a tools quality after 6 months of abuse
. I do use this method when installing hex shank driver bits since they only need to be snug for my use. Anything that needs to be torqued down in a keyless chuck should be done by hand as far as any manual I can find. This would include nearly all loosening operations, no? I try to follow this every time and may succeed 80-90% of the time
.