A C172 AT 1000 FT DURING A TEST FLT LOST ALL ENG OIL. ENG OPERATED FOR 2 MINS TO REACH ARPT. OIL LOST THROUGH FRONT CRANKSHAFT SEAL.

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I AM THE OWNER/PLT OF THE C172 (1970 MODEL). THE EVENT WAS A BLOWN FRONT CRANKSHAFT SEAL DURING A TEST FLT CAUSING LOSS OF ENG OIL AND RESULTING IN ZERO OIL PRESSURE FOR A PERIOD OF APPROX 2 MINS. THE ACFT WAS KEPT UNDER PWR TILL A SAFE ARPT LNDG COULD BE MADE WITH NO DAMAGE TO THE ACFT OR OTHER. ENG DAMAGE; IF ANY; HAS NOT BEEN DETERMINED AT THIS TIME. THE ACFT HAD BEEN RETURNED TO THE OWNER BY AI/MECH AFTER ANNUAL INSPECTION AND TEST FLT 4 DAYS EARLIER. AFTER 1.8 HRS OF ADDITIONAL FLTS; OIL DRIPS WERE NOTICED BY THE OWNER. ACFT WAS RETURNED TO THE AI/MECH TO CHK OUT. AFTER FURTHER INSPECTION AND WASH-DOWN OF THE ENG; THE AI/MECH SAID THE SOURCE OF THE LEAK WAS NOT FOUND AND REQUESTED THE OWNER TAKE ANOTHER TEST FLT FOR FURTHER CHKING. DURING THIS TEST FLT; THE SEAL BLEW OUT AS DOCUMENTED ABOVE. IMMEDIATELY AFTER THE EVENT; THE AI/MECH PULLED THE COWL; REMOVED THE PROP AND DISCOVERED THE BLOWN SEAL. HE THEN UPON FURTHER INSPECTION DISCOVERED A KINKED VENT TUBE HOSE; CAUSING BLOCKAGE AND EXCESSIVE ENG INTERNAL PRESSURE. THE AI/MECH SAID HE HAD INADVERTENTLY CAUSED THIS DURING THE ANNUAL INSPECTION. I FEEL THIS IS AN UNUSUAL ERROR FOR THIS AI/MECH. I CONTINUE TO HAVE CONFIDENCE IN HIS WORK.