After my reply above, we actually had the experience again, it's been awhile since the last one.
No problem with current installation, except a bit low on power (+4%) with a loaner turbine.
Turbine change after OH of our own- fails DCA check and stall check.
Swapping bleed valves - DCA ok, stall fail.
Swapping FCU - DCA fail, stall fail.
Engineers
Installing loaner compressor - DCA ok, stall ok
Since the turbine came from OH it was probably "tight" in the nozzle, and since the engine was a bit low on power the compressor was maybe not the best. New compressor cured the problem. The new compressor and OH turbine is +12% in pwr margin.
The problem engine was #2, during all swapping #1 was checked as well every time - no problem!
Just wanted to share this with you.
CB