Fuel filling 912ULS Rotax Engine

[ZU JPL]

I wanted to go fly around the windsock this morning. When I intend pulling the dipstick, the dipstick was covered with a fuel/oil mixture, because the oil tank was filled with mogas and the mogas/oil mixure dripped slowly from the oil tank overflow/breather pipe! Further investigation showed I forgot the fuel valve in the cockpit open. This wasn't the first time however that I forgot to clsoe the fuel valve. More flooding inside the engine was discovered, even the sump was full of mogas.

The leak took place over a period of two weeks and I lost approx 2 gallons of fuelduring that period.

 

The CTLS has 127 hours on the HOBBS and fuel tanks were emptied + engine ran ndry to empty the carburators . This procedure was done for the second time in the last two years, when I did not do any flying for 3-4 months.

 

It seems one of the seat & needles in a carburettor could be leaking, is this possible? has anybody experienced this problem before? What must I do now?

[Roger Lee]

Yes this can happen. It sometimes shows up on oil analysis too. It is always advisable to shut off the fuel when you are leaving the plane. It can happen even if the carb needle valve is okay. Leaving rubber parts dry for long periods can cause some leaks.

 

You have two choices.

If it is a very small amount you can run the engine and it will cook off. If it has filled the tank up to the plate or above where the dip stick sits, then this is a significant amount then drain the oil tank and put new oil in.

[Tip]

I had a bad fuel pump put gas in the oil circuit. It happened over a longer period of time and when the engine was running.

[Jim]

Your oil will never be the same. Change the oil and filter soon.