I'll agree that the RB211-524's that I've previously worked at AA were virtually troublefree.
On the other hand the CF6-50 is also extremely reliable, the only problem I've encountered with the VSV/VBV system being the feedback cables needing replacement due to binding. Usually this causing higher than normal EGT or other parameters to trend south. But their have been cases of CF6 stalling at high power due to *misrigged* VSV cables (with associated engine R&R).
The Pratt 4000 is a great engine but I don't like it near as much as the CF6-80.
First off is Pratts philosophy to use cowl load sharing to compensate for their insistance at using fewer bearings to support their rotating assemblies. Their cowl latching system turned a routine engine button up (GE) into a chore, especially on #2 engine on the MD11.
When I was told that to clear certain FADEC faults on the Pratt EEC you need to actually open the engine and remove one of the data plugs I was stunned (my first thought was #2). This is done on the CF6-80 inside the cockpit.
Durability wise the JT9 was superior to the CF6-6/50. I guess it had to be as stalling a JT9 was more prevelant than the CF6 (a very rare occurance). Yet now the point is moot as *both* Pratt and GE have very tight tolerances (the old Pratt addage, "damage can cause a stall but a stall won't cause damage", no longer applies).
Which CF6-80 engines have had their fan blades come apart? Is Pratt immune?
As a mechanic I respect your opinion. Some I agree and some not. If all mechanics agreed all the time, the breakroom would be a very boring place.
You're only as good as your last departure.