AN ACROBATIC PLT IS CONCERNED THAT HE ENTERED CLASS C AIRSPACE WITHOUT CLRNC DURING AN EMER RETURN TO A NEARBY ARPT AFTER AN ENG FAILURE.

Narrative

I WAS FLYING MY AEROBATIC ZLIN 50 IN MILD AEROBATICS. AS I CAME OUT OF A HAMMERHEAD; I NOTICED THAT THE PROP SPD DECREASED MARKEDLY. I HAD BEEN WATCHING THE OIL PRESSURE CAREFULLY; AS I WAS NEW TO THIS AIRPLANE; AND HAD SEEN THAT THE OIL PRESSURE WAS IN THE GREEN ARC; FLICKERING INTO THE YELLOW ONLY OCCASIONALLY WHEN TRANSITIONING FROM UPRIGHT TO INVERTED. ALSO; I NOTICED THAT THE OIL PRESSURE WOULD DROP OFF TO ZERO AT THE TOP OF THE VERT LINE; BUT THIS IS NORMAL. AFTER THE INCIDENT WHERE THE PROP RPM DROPPED OFF TO ABOUT 2000 RPM; I DECIDED TO END THE AEROBATIC SESSION AND RETURN TO THE ARPT. JUST AS I HAD PULLED STRAIGHT AND LEVEL; AND REDUCED THE THROTTLE; A LARGE AMOUNT OF OIL CAME OUT OF THE ENG AND SPLATTERED ON THE WINDSHIELD. THINKING THAT I HAD LOST A FRONT MAIN CRANKSHAFT SEAL; I THROTTLED BACK TO 0.4 ATMOSPHERES AND STARTED A GENTLE CLB DIRECTLY FOR THE ARPT; WHICH WAS SOME 10 MI DISTANCE. AT THIS POINT; THE OIL PRESSURE HAD DROPPED TO ZERO. I REDUCED THE THROTTLE TO IDLE; AND STOPPED THE ENG. I MADE A SUCCESSFUL DEAD STICK LNDG AT THE ARPT; WITH NO DAMAGE TO PLT OR AIRFRAME. DISASSEMBLY OF THE ENG REVEALED THAT THE THRUST BEARING ON THE CRANKSHAFT HAD SEIZED; EVEN THOUGH THE ENG STILL CONTAINED 8 QUARTS OF OIL. NORMAL OIL LOAD FOR AEROBATICS IN THIS AIRPLANE IS ONLY 10 QUARTS. IN MY EMER RETURN TO THE ARPT; I ENTERED AND PASSED THROUGH CLASS C AIRSPACE WITHOUT CONTACTING THE APPROPRIATE ATC FACILITY. PERHAPS I SHOULD HAVE CONTACTED ATC; EVEN GIVEN THE NATURE OF MY EMER; HOWEVER; I WAS KIND OF BUSY AT THE TIME.