Had one 2 weeks ago on a M140xbl. Was on down wind leg with 1/3 throttle gears down getting ready to come around and land. Luckily my Jeti telemetry spoke " oh sh*t, flame out". No white smoke. Landed safely. GSU says "low RPM" UAT was full, main tank Full more then 1/3. No air bubbles anywhere. Since then I have taken the fuel system apart and all looks good. Have had 75 flights with this engine on an Ultra flash without any problems. 6MM PU SMC tubing all around and 4mm from from pump to engine.. Have no festos in the system. I flew 5 more flights that day without any problems. Still can't figure out what happened.