{HEAD ~ A friction damper} provides {TAIL ~ friction damping} for gas turbine engine airfoils to reduce vibrations thereto 
{ HEAD ~ A friction damper } provides { TAIL ~ friction damping } for gas turbine engine airfoils to reduce vibrations thereto
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH