The rotor spindle and {HEAD ~ controls} pass through {TAIL ~ a central hole} between the spar caps 
pass through
The rotor spindle and { HEAD ~ controls } pass through { TAIL ~ a central hole } between the spar caps
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH