Yes, excuse me..got my Toyota Corolla stuck in the snow..four dachshunds..irate wife..and a couple of pet huskies causing distress to all..finally got the thing out and all occupants and home.
If I am not mistaken the central disc that was exploded out revolves in the opposite direction to the other rotors. I believe this is a feature of RR aerospace turbines if not all in the RB-211 pattern. If someone can confirm this?
So WTF am I taliking about..right? Well we know that this engine is a bypass design and a lot of air does not enter the combustion process. If I am not mistaken I believe this is about 10/15% that gets inducted in the burn section to be mixed with kero.
We know that the oil feeds are subject to hot gas and that the oil should be kept to below 150C. We know that the oil line in question was fractured and I know personally that it was fractured BEFORE this final failure...final failure..shiny crystaline surface on the metal. Old fracture is seen brown oil/corrosion/colour.
Cause of fracture: stress due to harmonic vibration. Only possible cause. Heat cycles added..severe for T-972 'cause of higher energy transfers at max TO weights AND high ambient temps as in S Cal and Australia.
From first principals the engine SUCKS SQUUEEZES BURNS then THRUSTS. The thrust part depends upon the kero/air ratio. The thrust turns the sucker fan at the front. In these new engines all of this is data mapped so the engine KNOWS WTF is going on and adjusts the fuel flow to match.
If you have an oil leak..the turbine oil gets mixed with the kero and changes the burn characteristic..in particular the TIME taken to release X amout of energy. RR are very proud of the fact that their products get more thrust out per total unit mass than the rest. As they boast "High in power, yet low in mass" with " low emissions".
All very well if the kero/air mix is right and the software is not confused. If you have turbine oil mixing with the air then with the kero the whole model is sent to hell. So the thrust turbine thinks it should have X amount of air with a weight of X amount of kero where as the reality is different.
So the different parts of the engine are out of sync.
This sets up a harmonic and the situations gets progressively worse. The vibrations get worse, the temps rise and eventually a part fails due to stress fracture. Of course if the central disc is turning the other way this can make the situation worse.