Inside the turbine, just underneath the cap on the front of the turbine, are a couple of Festo Fittings!

One of them is the propane entry to the turbine.

If there is not a check valve on the propane line, hot gasses when the turbine is running, will run up that line and melt the festo fitting inside the turbine cap.

This will cause no issues for you until you land, refuel, and go to start your engine again.

Propane will leak at that melted festo fitting, and you will come close to blowing yourself up, if you ever do get the engine to light off!

One day, while learning this, I shot liquid propane down the light trying to figure out what the hell was going on.

When that kicked off, oh boy, was it hot in my garage!

Thought I was a contender for the Darwin awards that day. I was on the phone with a buddy, dropped the phone while I was jumping to the fire ext and compressed air hose!