A unison ring assembly for a gas turbine engine has a unison ring and a plurality of levers extending from the unison ring. Each lever has a pin at one end that inserts through a bore of a respective bush mounted in the unison ring. Each bush is formed as separate first and second parts which are mounted to their through-hole by inserting the first part into the through-hole from one side of the unison ring and the second part into the through-hole from the opposing side of the unison ring. Each part has a respective stop which prevents that part from inserting into the through-hole by more than a predetermined amount. When both parts are inserted by their predetermined amounts, their ends join together to form the bush and prevent the parts being retracted from the through-hole.