A BEECH A36 BONANZA ON TEST FLT AT 1000 FT EXPERIENCED LOUD NOISE AND SEVERE VIBRATION. DECLARED AN EMER AND LANDED. CAUSED BY FAILED PROP BLADE LOCK.

Narrative

PURPOSE OF FLT WAS FLT TEST AFTER ANNUAL INSPECTION. PLAN WAS TO FLY A COUPLE TIMES AROUND LCL ARPT PATTERN AND LAND. ON FIRST TKOF AND CLBING TO 1000 FT ON XWIND LEG TURNING TO DOWNWIND; LOUD NOISE AND VIBRATION FROM ENG. CONTINUED TURN TOWARDS RWY; MADE MAYDAY RADIO CALL; AND LANDED WITHOUT FURTHER INCIDENT. INITIAL INSPECTION REVEALED 1 BLADE OF 3 BLADE PROP HAD ROTATED 180 DEGS (PAST PROP STOP). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ENG WAS STILL OPERATING; BUT HAD NO THRUST SO WAS SHUT DOWN. THE RPTR SAID INSPECTION REVEALED 1 BLADE WAS ALMOST IN THE FEATHER POS. THE RPTR STATED WHEN DISASSEMBLED IT WAS DISCOVERED A CTL PIN IN THE DEFECTIVE BLADE HAD SHEARED ALLOWING THE BLADE TO MOVE ALMOST 180 DEGS. THE RPTR SAID THE ENG INCURRED MAJOR DAMAGE AND WAS TORN DOWN. ALL 6 PISTONS HAD STRUCK THE CONNECTING ROD BEARING CAPS AND ALL STEEL PARTS WERE REMOVED FOR TESTING. THE RPTR STATED ALL GYROSCOPE INSTS WERE FOUND DAMAGED AND WERE REMOVED FOR REPAIR. THE RPTR SAID THE PROP MANUFACTURER (MCCAULEY) WAS ADVISED OF THE CTL PIN FAILURE AND STATED THIS IS A RARE FAILURE. THE RPTR STATED THE NTSB AND THE FAA WERE PRESENT WHEN THE PROP WAS DISASSEMBLED AND TOOK THE SHEARED CTL PIN FOR TESTING.