This is a generally tedious and inefficient process and a machining error in any one of the many blades may necessitate {TAIL ~ the scrapping} of {HEAD ~ the entire disk} 
This is a generally tedious and inefficient process and a machining error in any one of the many blades may necessitate { TAIL ~ the scrapping } of { HEAD ~ the entire disk }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD