To seal leak of cooling air by fixing a blade outer air seal 23 without increasing weight of a jet engine.

An outer seal assembly 10 of a turbine rotor stage is secured within a circumferential groove 17 of a casing 11 of the assembly 10 in such a manner as to both fix the outer seal assembly 10 in its installed position and also provide for sealing around its outer periphery so as to thereby prevent the leakage of cooling air therearound. A plurality of arcuate elements are provided to interface between radially extending arms 27 of the seal assembly 10 and the inner surface 18 of the casing. Each of the arcuate elements includes a radially extending panel 33, a plurality of forwardly extending hooks 34 that are disposed within the groove 17, and a forwardly extending flange 36 that engages the rear surface of the outer seal assembly arm 27. As the assembly 10 is urged rearwardly during operation, the arcuate element is caused to rotate about a fulcrum in the circumferential groove 17 such that a radially outer edge 41 of a panel 33 is urged against a inner surface 18 so as to thereby enhance the sealing relationship therebetween.