Narrative:

Some time last yr, a B model navion with a GO435 lycoming engine had a propeller strike at YYY airpark. Due to the propeller strike, the engine was torn down for a rebuild. An old time engine man with 40 yrs of backgnd performed the rebuild under my supervision. All work was done to lycoming books and manuals, using standard parts with complete return to service tags. All torque wrenches were in current calibration. On aug/sat/01 with about 12 hours on the engine on a flight from XXX to YYY, the pilot saw a rise in oil temperature, as well as a drop in pressure with a vibration at the simi valley pass. Passenger called in to ZZZ airport for a precautionary landing. At no time did the engine quit. The aircraft was placed in a hangar. The engine was removed for inspection. On the disassembly, it was found that a speck of sealant had lodged in the oil passage of the #1 journal causing T lack of lube to the bearing, thus the connecting rod failed at the butt end. The probable cause of the sealant was once the engine was reinstalled in the aircraft we had to remove the T drive and replace it. There was the possibility that a bit of the sealant compressed into the accessory case then was circulated around the system until it was trapped by the oil port. There was no damage to the aircraft, nor injuries to the pilot or passenger. To best prevent a recurrence of this type of incident, use the minimum amount of sealant possible. As a note, this is the first time I have ever had a problem with an engine that I have overseen or rebuilt myself.

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Original NASA ASRS Text

Title: A NAVION B DIVERTED DUE TO HIGH OIL TEMP AND LOW OIL PRESSURE CAUSED BY LOOSE GASKET SEALANT RESTRICTING OIL PORT.

Narrative: SOME TIME LAST YR, A B MODEL NAVION WITH A GO435 LYCOMING ENG HAD A PROP STRIKE AT YYY AIRPARK. DUE TO THE PROP STRIKE, THE ENG WAS TORN DOWN FOR A REBUILD. AN OLD TIME ENG MAN WITH 40 YRS OF BACKGND PERFORMED THE REBUILD UNDER MY SUPERVISION. ALL WORK WAS DONE TO LYCOMING BOOKS AND MANUALS, USING STANDARD PARTS WITH COMPLETE RETURN TO SVC TAGS. ALL TORQUE WRENCHES WERE IN CURRENT CALIBRATION. ON AUG/SAT/01 WITH ABOUT 12 HRS ON THE ENG ON A FLT FROM XXX TO YYY, THE PLT SAW A RISE IN OIL TEMP, AS WELL AS A DROP IN PRESSURE WITH A VIBRATION AT THE SIMI VALLEY PASS. PAX CALLED IN TO ZZZ ARPT FOR A PRECAUTIONARY LNDG. AT NO TIME DID THE ENG QUIT. THE ACFT WAS PLACED IN A HANGAR. THE ENG WAS REMOVED FOR INSPECTION. ON THE DISASSEMBLY, IT WAS FOUND THAT A SPECK OF SEALANT HAD LODGED IN THE OIL PASSAGE OF THE #1 JOURNAL CAUSING T LACK OF LUBE TO THE BEARING, THUS THE CONNECTING ROD FAILED AT THE BUTT END. THE PROBABLE CAUSE OF THE SEALANT WAS ONCE THE ENG WAS REINSTALLED IN THE ACFT WE HAD TO REMOVE THE T DRIVE AND REPLACE IT. THERE WAS THE POSSIBILITY THAT A BIT OF THE SEALANT COMPRESSED INTO THE ACCESSORY CASE THEN WAS CIRCULATED AROUND THE SYS UNTIL IT WAS TRAPPED BY THE OIL PORT. THERE WAS NO DAMAGE TO THE ACFT, NOR INJURIES TO THE PLT OR PAX. TO BEST PREVENT A RECURRENCE OF THIS TYPE OF INCIDENT, USE THE MINIMUM AMOUNT OF SEALANT POSSIBLE. AS A NOTE, THIS IS THE FIRST TIME I HAVE EVER HAD A PROB WITH AN ENG THAT I HAVE OVERSEEN OR REBUILT MYSELF.

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.