Oil Temp
Mach E Avelli. I have spent many thousands of hours monitoring engine and system performance as a Flight Engineer and I can honestly say that I have never known an oil system with the appropriate level of oil in it to run hotter than it would with less oil in the reservoir. Why your Jabiru apparently does is odd, in my view, to say the least. I have operated JT3D-3B's and RB211's as well as Allison T56 engines. Fuel cooled oil coolers which double as fuel heaters have rarely caused problems as distinct from air cooled types such as fitted to the Allison. Temperature control is maintained by varying the oil cooler flap position. My experience of piston engines has been varied and includes R985, R1830 and Bristol Sleeve valve Hercules as well as GA light aircraft engines of various configurations. I would genuinely be interested to know why your Jabiru reacts in the way it does if others have an explanation. As for the oil temperature decreasing with decreasing quantity on the 146, I can only assume that the oil temperature sensor must be similar to many motor vehicle engines and as the quantity fell below the level of the sensor there was no means to transfer the heat from the oil to the sensor. You did not say whether the oil pressure increased at all when you initially noticed the decrease in oil temperature. It would have been a normal reaction for the pressure to increase with falling oil temp. BTW, you obviously saved a lot of money for your company by conducting the precautionary shutdown. Sometimes it does pay to act before any limit is exceeded. Happy Landings.
Last edited by Old Fella; 3rd March 2009 at 10:53.