ENG FAILURE AND OFF ARPT FORCED LNDG.

Narrative

ACFT WAS 1000 FT AGL ENG OPERATING AT 2400 RPM; WHEN ENG QUIT. NO BACKFIRING; NO MISSING; JUST QUIT AND STARTED WINDMILLING. PLT MADE VISUAL APCH INTO COW PASTURE. THE ACFT CONTACTED COW FEEDER AND WENT THROUGH FENCES AND ENDED WITH THE TAIL RESTING AGAINST A HOUSE. PLT AND PAX BOTH EGRESSED THE ACFT SAFELY WITHOUT A SCRATCH. THE ACFT RECEIVED EXTENSIVE DAMAGE. L GEAR TORN OFF; L WING SPARS BROKEN OUTBOARD OF STRUTS AND THE TAIL SECTION WAS TWISTED APPROX 10 DEGS WITH R ELEVATOR AND HORIZ FIN DAMAGE. INITIAL INVESTIGATION OF ENG HAD PLENTY OF FUEL. THE L MAGNETO WAS BROKEN AT CASE. UPON REMOVAL OF BOTH MAGNETOS THE 4 BOLTS TO CRANKSHAFT GEAR WERE FOUND BROKEN. THE CASE HAD A PIECE 1 IN BY 1 1/2 IN BROKEN JUST AFT GEAR. THE L MAGNETO HAD A GAUGE IN GEAR 1 TOOTH AND THE STARTER CLUTCH WAS FROZEN OR WAS IN THE ENGAGED POS. NOTE THE CLUTCH WAS INSTALLED .4 OF HR. IT WAS AN AEROTECH STC PMA CLUTCH. MATED TO A PRESTOLITE MZ-4214 STARTER THAT WAS ORIGINAL FROM THE FACTORY. THE ENG WAS SENT TO THE NTSB BOARD IN MOBILE FOR TEAR-DOWN TO TRY TO DETERMINE CAUSE OF BOLT FAILURE OR CLUTCH FAILURE; OR SOME OTHER PORTION OF THE ENG THAT CAUSED THE CATASTROPHIC FAILURE. THE INSTRUCTIONS FOR INSTALLING THE CLUTCH IDENTIFIES TCM SB M70-10 HAS BEEN COMPLIED WITH AND TO CALL IF UNSURE (A CALL WAS MADE AND AM STILL NOT SURE. A SPECIAL CAUTION OR ATTN SHOULD BE MADE. NOW ONLY THE NTSB INVESTIGATION WILL DETERMINE WHAT WAS THE REAL CAUSE OF THE FAILURE ON THIS ENG. SEE ATTACHMENT #1. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS THE MECH INVOLVED WITH THE ENG FAILURE. THE FINAL DETERMINATION OF THE CAUSE OF THE ENG FAILURE HAS NOT YET BEEN DETERMINED BY THE NTSB. THE TIMING/CRANKSHAFT GEARS WERE STRIPPED; BUT; IT IS NO KNOWN WHETHER THE ELECTRIC STARTER OR THE MAGNETO CAUSED THE GEARS TO BE STRIPPED.