A MOONEY 20J IN CLB AT 3500 FT RETURNED TO LAND DUE TO LOSS OF ENG PWR. CAUSED BY THE 'DUPLEX' MAGNETO SEPARATING FROM THE ENG.

Narrative

I DEPARTED SALINAS ARPT ON RWY 26; DURING VMC AT APPROX XA45 LCL TIME. AFTER TKOF; GEAR UP; CHKING FOR NORMAL INDICATIONS AND TRIMMING THE ACFT FOR CLB; I TURNED TO A HDG OF 020 DEGS WITH THE INTENT OF LNDG AT 3O7 SOME 17 MI AWAY. AS I WAS CLBING AT 100 KTS; I HEARD INCOMING TFC CONTACT THE TWR ON A FLT PATH THAT WOULD INTERSECT MY FLT PATH. TO AVOID ANY CONFLICT; I INCREASED MY CLB ANGLE TO VY (BEST RATE) AND CONTINUED ON COURSE. APPROX 3 MINS AFTER TKOF; THE ENG CEASED MAKING PWR; AND THE RPM'S DROPPED FROM 2700 RPM TO ABOUT 1800 RPM. ALL OTHER GAUGES WERE WITHIN THEIR NORMAL PARAMETERS. FUEL PRESSURE WAS NORMAL; OIL PRESSURE WAS NORMAL; CHT AND OIL TEMPS WERE NORMAL. I PUSHED THE NOSE DOWN TO ESTABLISH A DSCNT AT V-GLIDE (100 MPH); TURNED TO THE R TOWARD SALINAS ARPT; AND NOTIFIED THE TWR I HAD LOST PWR AND WOULD BE RETURNING TO THE FIELD. AFTER I SWITCHED FUEL TANKS; AND CYCLED THE FUEL BOOST PUMP ON AND OFF; WITH NO EFFECT ON THE ENG; I DECLARED AN EMER. THE SALINAS TWR CLRED ME TO LAND ON RWY 26; WHICH I DID WITHOUT EVENT. UPON COASTING TO THE RAMP; AND SECURING THE ACFT; I EXITED THE ACFT AND PUSHED IT TO THE TRANSIENT PARKING AREA. A POSTFLT CHK REVEALED A MINOR AMOUNT OF FUEL DRAINING FROM THE MANIFOLD OVERFLOW/BREATHER LINE; AND A MINOR (BUT MORE THAN TYPICAL) AMOUNT OF OIL ON AND AROUND THE NOSEWHEEL. THE OIL LEVEL WAS NORMAL. I TURNED THE PROP BY HAND. THE ENG HAD GOOD COMPRESSION; HOWEVER I WAS UNABLE TO HEAR THE MAGNETO IMPULSE COUPLING 'CLICK' AS I CRANKED THE ENG. IT WAS LATER DETERMINED THAT THE MAGNETO SEPARATED FROM THE ENG.