B73....read the statement very carefully....it said "indications of a failure" which does not mean the system actually failed.
My impression upon reading the AAIB report was the Glycol system worked...but Cockpit indications were it had failed. HC and others discussed the fallibility of the sensors associated with the glycol system and noted their TBO was halved after routine Engineering protocols determined the problems with them indicating properly.
I am sure HC shall set me straight if I am off in this.