As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TO, ENGINE SURGED AND DECREASING NR 2 ROTOR SPEED AND INCREASING EGT TAKEOFF CONTINUED, ENGINE SHUT DOWN AND AIR TURNBACK ACCOMPLISHED. DISASSEMBLY INSPECTION REVEALED HTP 1ST STAGE OUTER AIRSEAL (ROTATING) FAILED MATERIAL HAS BEEN SENT FOR REVIEW AND ANALYSIS.