What was found
(CAN) DURING 300 HOUR SCHEDULED COIN TAP TEST ON PROPELLER, IT WAS FOUND BY INTERPRETING THE SOUND DURING THE TEST THAT A SIGNIFICANT PORTION OF THE LEADING EDGE OF ONE OF THE PROPELLER BLADES WAS INDICATING A DELAMINATION & DEBONDING. THE LEADING EDGE JUST OUTBOARD OF THE DEICE BOOT SHOWS A CRACKING & DELAMINATION. RESEARCHED THE CRITERIA FOR AIRWORTHINESS. CONTACTED AN APPROVED DEALER & DISCUSSED THE PROBLEM. INDICATED THAT THERE ARE OPERATORS THAT HAVE HAD A SIMILAR ISSUES. DISCUSSION RESULTED IN AMO GROUNDING THE ACFT UNTIL THE PROPELLER IS SENT FOR REPAIR.