There is a minhag to fast when a Sefer Torah is dropped. Does this apply if the dropped Torah was pasul (not "kosher")?
My thinking - a pasul Torah is not a "true" Torah in the sense that it can be used for congregational reading. However, it still maintains its holiness and it needs to be buried if one wants to "dispose" it. But, despite that, perhaps, the minhag applies only to usable Sifrei Torah?