colpaz Turbine D
There is no track record for the "Stub Pipe" issue, and since RR "Sprung" the Stub Pipe issue on everyone, in hopes of diminishing the severity of the Powerplant issue, The 75 cycles is related to the Splines, the AD's, and the 972. 75 cycles is about ninety days for Qantas, as I reckon it, and the AD has not been satisfied. The Oiling issue is new, at least as far as RR would have it.
The AD is demanding of STRIP, not a simple Mx, and as I see it, not an on wing process. I stand to be corrected. The Spline Wear has to do with the HP/IP Thrust bearing end of the Shaft (forward), there are no Splines at the Aft Roller Bearings, the "Site" of the Oiling issue related to Fire, related to uncontained Burst, etc.
The fog is deliberate. The 972 should have been given a miss, relative to Qantas and their long haul aspirations. Eight thousand pounds of Thrust left in the Hangar in favor of 970's must seem like to drool over about now, for Qantas. What can 970's cost in MTOW and Pax/Freight? Some, I suppose, but again, the 972 is a mission killer as it stands now.
The IP Shaft/Spline Shaft couple had to do with the original report of lost IPT, QF32. "Loss of Rigid Coupling". It is this area that is causing the grief, the oil issue is a handy scapegoat, IMO. Worn Thrust Pocket "Abutments" that nest the Splines in their Troughs are the issue (according to the AD's). Though a "Module", if there are design issues here, the implications for permanent fix are problematic, and involve the 970 on up to the 980. RR can't possibly be entertaining a change out of The entire IP Module every ninety days, and the 970 is an identical engine; who will believe that a mere 2000 pounds of thrust separates identical twins from the same mechanical pitfalls??
Curiouser, Curiouser.
Alternate, and better prognosis. The AD is related to Oiling insufficiencies in the 972 only (By "happenstance"). If so, the entire Oiling system could be upgraded, changed out, and there you go. Peas under the mattress as it were. Let's hope it is that simple.
bear