As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AIRCRAFT LIFTED OFF STAGING AREA WITH SLING LOAD. LOUD NOISE HEARD 2 MINUTES INTO FLIGHT. NO CAUTION LIGHTS OR OTHER INDICATION OF PROBLEM OTHER THAN LOUD AND HIGH-PITCHED NOISE. AIRCRAFT TURNED BACK AND MADE A NORMAL LANDING AND SHUT-DOWN. TURBINE WAS REMOVED AND SENT FOR INSPECTION. ONE BLADE FOUND MISSING FROM FIRST STAGE TURBINE WHEEL. SUSPECT CAUSED BY TIP RUB. INFORMATION AND PHOTOS FORWARDED TO MFG.