Crumbs

Question

I saw in your father's sefer that R. Aharon Kotler didn't search his books before chametz, and earlier you wrote that we are not concerned about crumbs. But why not? Can't you eat a crumb of chametz if you find it -- especially if it is a big crumb? Even if we don't have to be concerned about this, and therefore do not need to search, what do you do if in fact you come across a crumb of chametz on Pesah.