With OAT around 8°C my 912UL routinely makes 5300 rpm on climb, and the oil temp barely crosses 180F and the pressure is usually greater 52 psi.
On departure yesterday my rpm declined to 4900-5000 rpm from 5300 rpm on takeoff, and the oil temp temp shot up to 223F and oil pressure dropped to about 40psi within 3 minutes. EGT was normal in the 1480F range. I turned around and landed. I shut down the engine for enough time to call my destination and tried again. This time the engine performed perfectly--a completely normal takeoff with my usual numbers indicated. I flew 65 minutes to my destination, where I spent three hours.
Departing from my destination the same troublesome scenario developed. Immediately on departure the rpm dropped to 4900/5000 rpm, oil temp rose fast and oil pressure dropped. I turned around again. I shut down. After securing the aircraft, I did a ground run in which everything seemed fine, and decided to depart. This time the engine performed normally, and cranked it out just fine for the 90 minute flight home.
All of the fuel and air filters have about 30 hours on them since replacement or cleaning. The gascolator was serviced at the same time, as well as replacing all of the fuel lines and Rotax fuel pump. The fuel flow in all situations was 4-5 gph, so normal.
What could have caused the takeoff performance issues?
