A PA-28 PVT PLT MAKES AN EMER FORCED OFF ARPT LNDG AS THE ACFT SUFFERS EXTREME VIBRATION.

Narrative

I HAD JUST FINISHED A PHANTOM APCH WITH A STALL. I INCREASED PWR AND CLBED APPROX TO 5000 FT AGL. I EXPERIENCED LOSS OF THRUST FOLLOWED BY A KNOCKING -- BUZZING NOISE THAT PROGRESSED INTO VIOLENT SHAKING OF THE ACFT. I FIRST LEVELED THE ACFT; THEN WENT THROUGH EMER PROCS. I THROTTLED BACK AND FLEW THE AIRPLANE AT 80 KTS; BUT THE ACFT WAS STILL VIOLENTLY SHAKING. I TRIED TO DIAL 121.5 AND COULD NOT. I PREPARED TO MAKE AN IMMEDIATE LNDG. WE SPOTTED A FIELD AT OUR 2 O'CLOCK AND I SET UP FOR AN APCH. WHILE SETTING UP FOR THE LNDG; I PULLED THE MIXTURE FULL LEAN AND INCREASED THE PWR TO 1500 RPM TO KILL THE ENG; BUT THE ENG WOULD NOT QUIT. I THROTTLED BACK AND SLIPPED THE PLANE UNTIL 20 FT AGL. I STRAIGHTENED THE PLANE AND DID A 2 POINT LNDG; LET THE NOSE WHEEL DOWN; AND APPLIED BRAKES. THE ENG WOULD NOT SHUT DOWN; SO I TURNED THE MAG SWITCH OFF WHEN THE RPM FLUCTUATED TO ITS SLOWEST CYCLE. IT WASN'T TILL AFTER THE ENG SHUT DOWN; THAT I THEN NOTICED THAT THE PROP WAS MISSING 5 INCHES OFF THE TIP. THEN I MADE CONTACT WITH WJF.