yeah, it's in one of those paths.
try to echo the $PATH (if u r running a shell) and see if paths are there, if they are, chances are u can just use "whereis fsck" or "which fsck". If not, check those paths (/sbin, /bin, /usr/bin, /usr/sbin/, etc)
oh and of course u have to be root, just run
and login as root
hope that helps