You mention that an "air bubble" is an obvious cause of a flame out. Well when it happens to you I will bet it won't be so obvious. I had an unexplained flame out and still have no idea why. Ran fine for two full tanks right after (on the ground with me shaking the heck out of it to recreate the problem). I am fairly certain it was an air bubble trapped in the fuel filter but still can't be 100%. The thing about a flame out (at least on my turbine) due to an air bubble is that it doesn't get recorded as a malfunction on the GSU. I would have rathered it have been something that I could have fixed like a temp sensor etc.. because those things get recorded as a fault.