What was found
RTFL UNDER AMBER ALERT AFTER EXPERIENCING SURGE ON NR 2 ENGINE. ENGINE WAS REPLACED AT SFO. SHOP TEARDOWN FOUND HEAVY HPC BLADE DAMAGE THROUGHOUT THE COMPRESSOR. THE DAMAGE RESULTED FROM LIBERATION OF OF SEVERAL STAGE-6 VARIABLE STATOR VANE TRUNNION 'BUTTONS'. THIS IS A KNOWN INDUSTRY PROBLEM. CURRENT FIXES ARE TO RTV THE INNER SHROUD CAVITIES TO CONTAIN BROKEN BUTTONS, AND PREVENT THEM FROM ENTERING THE GASPATH. THE SECOND FIX IS TO INSTALL NEW MATERIAL INNER TRUNNION BUSHINGS THAT ARE MORE RESISTANT TO WEAR. UA INCORPORATES BOTH AT HPC REBUILD.