The collective control for pitch change employs {HEAD ~ a coil spring} mounted between a pitch horn and {TAIL ~ a hub} 
The collective control for pitch change employs { HEAD ~ a coil spring } mounted between a pitch horn and { TAIL ~ a hub }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL