FWIW, Honeywell has had "T5 limiting" on their early 731 engines (70's vintage), and I believe it's on the -20, 40 and 60 series but not sure (90's vintage). I'm told that if ITT gets to the magical number, the EEC, or DEEC in the case of the later, sends a signal that reduces fuel flow by 2%. Don't ask me for further, that's all I know. And I realize it's not a PW, GE, nor RR.