Narrative:

Aircraft was 1000 ft AGL engine operating at 2400 RPM, when engine quit. No backfiring, no missing, just quit and started windmilling. Pilot made visual approach into cow pasture. The aircraft contacted cow feeder and went through fences and ended with the tail resting against a house. Pilot and passenger both egressed the aircraft safely without a scratch. The aircraft received extensive damage. Left gear torn off, left wing spars broken outboard of struts and the tail section was twisted approximately 10 degrees with right elevator and horizontal fin damage. Initial investigation of engine had plenty of fuel. The left 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 left magneto had a gauge in gear 1 tooth and the starter clutch was frozen or was in the engaged position. Note the clutch was installed .4 of hour. It was an aerotech stc pma clutch. Mated to a prestolite mz-4214 starter that was original from the factory. The engine 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 engine 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 attention should be made. Now only the NTSB investigation will determine what was the real cause of the failure on this engine. See attachment #1. Callback conversation with reporter revealed the following information: the reporter was the mechanic involved with the engine failure. The final determination of the cause of the engine 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.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.