Please look at the Picture of the Aft LP Shaft. Take note of the soot ring. Locate that evidence under the Spline joint. Notice the well defined after portion of this ring of soot. From this well defined border, note that the soot seems to lighten and form a less sharp terminus as it moves forward.
High pressure oil fire gases have exited the Spline Joint at the connection of the two IP Shafts. Entering the space between the IP Shaft and LP Shaft, they encounter P30 pressure and quickly are routed forward. They continue to move forward and out the LP cowling, showing the Sooty streaks on the cowl.
The original AD has not been satisfied Publicly. RR is doing work that is under a device, an umbrella if you will, addressing a Duff Tube, as if it caused everything. No reporting of this "work" is ongoing. This engine has deeply problematic issues that degrade internals such that an inspection cycle of every third landing was proposed and enforced.
These issues? Every impact that can be imagined on Splines that historically have a virtual 100 per cent record. Metal in the Oil? Residue? Failed Oiling Couples? How much of Rolls Royce's authority as to compliance and airworthiness is to be respected (Other than by EASA) when they don't disclose serious issues to their clients? Rolls is doing workarounds under the cover of one tube that may not have been onboard. It is outrageous that EASA leaves to the Manufacturer all authority for airworthiness.
FAA FOIA