C152 PLT LOSES PWR AND IS FORCED TO LAND OFF ARPT.

Narrative

OFF ARPT LNDG DUE TO LOSS OF PWR. NO INJURIES; NO DAMAGE TO ACFT. LANDED ACFT ON ROADWAY OUTSIDE OF POPULATED AREA. NO TFC CONFLICTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVISED SIT CAUSED BY ENG FAILURE. A MAJOR 'TOP END' ENG JOB HAD BEEN COMPLETED; AND THE RPTR WAS CONDUCTING THE REQUIRED LYCOMING ENG TEST AND BREAK-IN PROC. AS THE RPTR STATED; LYCOMING REQUIRES A NEW WASHER TO BE INSTALLED WITH RECOMMENDED TORQUE. THE PROB IS THAT THE BOLT CAN'T BE TORQUED AND THE GAUGE GAP MAINTAINED -- THERE'S NOT SUFFICIENT ROOM TO DO BOTH AT THE SAME TIME; AND THERE IS NO SAFETY WIRE. THE BREAK-IN PROC REQUIRES A 1 HR TEST. DURING THE TEST FLT; THE NUT WORKED LOOSE; CAUSING THE EXHAUST VALVE TO COLLAPSE CLOSE; CAUSING SUFFICIENT BACK PRESSURE TO BLOW THE INTAKE VALE; WHICH BENT THE CONNECTING ROD; CAUSING THE LOSS OF THE CYLINDER. A C152 WILL NOT FLY ON 3 CYLINDERS. THE RPTR ADVISED THAT ALL PARTS FAILED AS THEY SHOULD WITHOUT FURTHER ENG DAMAGE. LYCOMING IS ALLEGEDLY AWARE OF THE OVERALL PROB. THE FAA WAS NOTIFIED.