I have an OS engine in my Raptor 90. Purchased it from someone who had conducted about 6 ten minute flights. He experienced some starting problems as I have which have resulted in hydra lock. I flew the heli for the 1st time the other day but was only able to get it running after it was totally flooded and am wondering if some engine damage could have ocurred. After about 5 mins of running the engine started acting up, surging in what sounded like a lean condition and when on the ground to check the fuel level and at a medium idle it flamed out when I attmepted to add throttle.

I refueled and approx 2 mins after taking off the engine appeared to flame out at about a 30' hover. I attempted an autorotation but when it was about a foot off the ground I applied full collective on what I thought was a dead engine and it fired back at full throttle (no onboard glow)! Not sure what happened at this point but I am thinking that it folded the mains from the power burst and it crashed falling over on it's side and beating itself for a few seconds until the engine quit.

Is it possible that the head gasket was damaged causing a lean condition? Another possibility is that the fuel valve is damaged and leaking air which I will explore. Want to find the source of my problem prior to flying again to reduce the risk of a repeat of this, it was not pretty... Also for added info I was using a hydrotork starter which also concerns me about an engine damage possibility.

Thanks for any feedback...