A C150 CFI RPT ON THE DESIGN FEATURE OF THE FIRE SHIELD THAT OVERLAYS THE OIL LINES BTWN THE OIL COOLER AND THE ENG. THE OIL LINE RUPTURED WITHOUT ANY NOTICEABLE DROP IN THE OIL PRESSURE. RPTR CLAIMS THAT THE SHIELD FACILITATES THE BUILD-UP OF MOISTURE AND SUPPORTS THE EROSION OF THE OIL LINE.

Narrative

THE SIT THAT OCCURRED WAS A COMPLETE DROP IN OIL PRESSURE WITH NO INDICATION OF A TEMP INCREASE. IN FACT; THE TEMP REMAINED NORMAL ON THE LOW END OF THE GREEN ARC. THE CAUSE WAS A COMPLETE LOSS OF OIL DUE TO A RUPTURED OIL LINE BTWN THE OIL COOLER AND THE ENG. THIS TOOK PLACE APPROX 20 MINS INTO A CHK-OUT TRAINING FLT IN THE C150/150 BY A CFII FOR A NEWLY RATED PVT PLT. THE ENTIRE FLT FROM THE BEGINNING TO THE TIME WE SHUT IT DOWN WAS 5/10THS. WE PROCEEDED INBOUND FROM THE PRACTICE AREA AFTER COMPLETING SLOW FLT AND STALL SERIES; DURING WHICH; THERE WAS NO INDICATION OF ENG ROUGHNESS; LOSS OF PWR; OR DROP IN PRESSURE. HOWEVER; THERE IS A QUESTIONABLE PERIOD OF TIME BEFORE WE PROCEEDED WITH DEP STALLS WHERE OUR ATTN WAS DIVIDED ON TFC; CLRING TURNS; THEN MANEUVERING. WE DID NOT HEAR OR VISUALLY NOTICE ANY CHANGES IN OIL PRESSURE OR PWR. WE FINISHED THE MANEUVERS AND BEGAN TO DSND TO THE ARPT AND UPON LNDG; I INSTRUCTED THE PLT TO TOUCH AND GO. WE NOTICED A DRAMATIC CHANGE WHEN WE APPLIED PWR; SO WE ABORTED THE TKOF; TAXIED TO THE RAMP; NOTICING THE PRESSURE DROP; AND SHUT IT DOWN. THE A&P SHOWED US THE OIL EVACED OUT OF THE BOTTOM OF THE ACFT BLOWING THROUGH THE OIL HOSE THROUGH THE FIRE SHIELD COVERING THE HOSE. I LEARNED THE FIRE SHIELDS HAVE 2 PURPOSES: 1) TO PROTECT AGAINST AN OIL FIRE IF THE EXHAUST MANIFOLD SHOULD MALFUNCTION; 2) THEY ARE PLACED OVER THE HOSES FOR AESTHETIC REASONS. THE FORMER IS NOT A MANDATORY REQUIREMENT SINCE THESE LINES ARE AN AMPLE DISTANCE FROM THE EXHAUST MANIFOLD. THE LATER IS THE PRIMARY REASON FOR FIRE SHIELDS ARE INSTALLED ON THESE HOSES. FIRE SHIELDS INSTALLED ON THESE OIL HOSES PRESENT A DOUBLE PROB FOR CESSNA OWNERS AND OPERATORS: 1) MOISTURE BUILDS UP BTWN THE FIRE SHIELD AND OIL HOSE CAUSING DETERIORATION TO THE OIL LINES; 2) IT DOES NOT FACILITATE AN EASY VISUAL INSPECTION BY AN A&P DURING INSPECTION TIMES; NOR THE PLT BEFORE HE FLIES. SIMPLE VISUAL INSPECTION COULD PREVENT THIS COSTLY PROB; EVEN AN ACCIDENT. NO MSDR HAS BEEN FILED BY THE A&P ON DUTY; AND IS IN PART WHY I WISH TO FILE THIS RPT. BY NOT INSTALLING THESE FIRE SHIELDS TO GUARD AGAINST DETERIORATION AND TO MAKE VISUAL INSPECTIONS DURING PREFLT TAKES PRIORITY OVER THEIR FUNCTION TO PROTECT AGAINST A RUPTURED MANIFOLD EXHAUST. THE LATTER IS A HIGHLY RARE OCCURRENCE; WHILE THE FORMER PROB -- DETERIORATION AND RUPTURED OIL LINES IS PROMINENT.