Variable stator vane assembly and bushing thereof

A variable stator vane assembly comprising:

• a) a rotatable variable-stator-vane trunnion consisting essentially of steel or titanium which is disposed in a through hole extending between outer and inner surfaces of a compressor casing of a gas turbine engine;
• and
• b) a first metal bushing consisting essentially of steel or titanium which is disposed in the through hole proximate the outer surface and which surrounds a first portion of the trunnion, wherein the first metal bushing and the first portion have wear-resistant coatings consisting essentially of a ceramic disposed thereon which are in mutual contact, apart from any intervening lubricant, when the trunnion is rotating with respect to the first metal bushing;
• c) a second metal bushing consisting essentially of steel or titanium which is disposed in the through hole proximate the inner surface and which surrounds a second portion of the trunnion, wherein the second metal bushing and the second portion have wear-resistant coatings consisting essentially of a ceramic disposed thereon which are in mutual contact, apart from any intervening lubricant, when the trunnion is rotating with respect to the second metal bushing;
• and
• d) a gas seal which is disposed in the through hole and which surrounds a third portion of the trunnion, wherein the third portion is disposed between the first and second portions, and wherein the gas seal is more flexible than either of the first and second metal bushings.