Maxtork,
Excellent info which raises another question in my mind, hopefully one you can help with. If I understand correctly, shutting the engine down while the rear bearing temperature is increasing can cause the oil which is in contact with the bearing to "carbonise" when the oil flow across the bearing slows & stops. Let me set the scene for my question - I am conducting a vertical descent into a confined area & the engine oil temperature increases above 80 deg causing the oil cooler fan to come on. I settle the helicopter on the ground, reduce the engine RPM to 70% Ng & start my 30 sec count. If after 30 secs the cooler fan is still running & the engine oil temp is say between 70 & 80 deg, should I shut the engine off or leave it running to supply oil flow to the rear bearing until the temp reduces to the point where the fan switches off? I stand by in anticipation of your wisdom.
P.S. - We run Mobil 254 oil.