The blades are fabricated with {HEAD ~ a root portion} having {TAIL ~ a cavity} adapted to mate with the disk protrusions 
The blades are fabricated with { HEAD ~ a root portion } having { TAIL ~ a cavity } adapted to mate with the disk protrusions
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH