The formula here is simple guys.
Blades from the High Pressure Compressor stage 6 keep failing at the root. Once they let go, massive damage is caused as the part flies through the rest of the compressor and then the turbine hence all the sparks and heat. Qantas keep refering to this as an overheated engine that is shut down as a "precautionary measure". Of course they also say it is not a safety issue.
This aircraft, OJL had a similar failure on Eng 4 in BKK a month ago. The good news is that there is a known fix to this problem by way of modification. The bad news (for Qantas) is that they can't carry out the modification becasue they closed their Roller engine shop last year. The Asian shops they use now are all booked out so the mod is not being done until an engine comes off for routine service.
I'd be expecting a few more of these failures. I think this is about the 10th one.