Replies to This Discussion

Permalink Reply by Phill Barnes on May 31, 2010 at 4:31am

Hi Thomas
I did my training in a Sportstar with a 912S 100hp. I was cautioned by my instructor not to rotate the prop backwards as it may damage the vac pump for the AH. I am not aware of any other components that might be damaged. I am not a Rotax expert but I thought that I might let you in on the info that I had seeing that no one else has. Have you asked your question to the Rotax dealer?

Phill

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Permalink Reply by Thomas Richardson on May 31, 2010 at 6:40am

No not yet with the holiday and all. W ill call them tommorow

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Permalink Reply by Jacob on May 31, 2010 at 6:45am

I know on oil changes they caution you not to do it because it can draw air into he hydraulic tappets I'd say you would be unlucky for it to happen though. Definately talk to some more experienced with rotax engines just to be safe.

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Permalink Reply by Bob Pustell on May 31, 2010 at 9:36am

Both problems that I am aware of have been mentioned.

Rotating ANY vacuum pump equipped engine backwards might damage the pump (assuming it is a vane type pump, which most are).

Rotating a four stroke Rotax backwards causes the oil pump to rotate backwards and pumps air into the oil pressure lube system. I do not know exactly what problems this causes, but I know it can be a problem. Hopefully, when you talk to the experts tomorrow, they can tell you how to undo whatever problem may have been generated. Good luck.

Let us know what you learn, please. Always good to have knowlege.

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Permalink Reply by Mike Hammond on May 31, 2010 at 11:45am

Just rotate the crankshaft in the correct direction unitll bubbles are heard in the oil tank. This will force oil through the engine and reprime the hydraulic lifters and the camshaft journals.

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Permalink Reply by Jonathan Porter on June 1, 2010 at 10:56am

You are not the first! And you are not the last!!! Most never own up to it... Apart from the warning above... this is what we do....

We had a student do it - it CAN put air in the system but all we did is the correct oil level check ie.

1. Check Mags are off, key is out, throttle is back.
2. remove the cap from the oil reservoir and the dip stick (the cap must be off and you must be able to listen to the cap orifice!)
3. Rotate the prop SLOWLY in the correct direction until it 'burps' (about 3 to 10 times)
4. wait about 5 seconds
5. dip the oil tank (should be between the middle and upper level - the upper level if for a long flight)
6. Replace the dip stick and secure the cap
7. Replace the cowling and prepare the aircraft for an engine run.
8. Start the engine and check for oil pressure in the first few seconds (1.5 - 5 bar although up to 7 for a few seconds if it is REALLY cold and you have a thick oil).

If you are unsure, run it up on the ground for 15mins and check all the 'vitals'.

Never fly unless you are comfortable with the engine and airframe - NEVER.

Finally, the Rotax is, generally, a very solid and forgiving engine -WE LOVE THEM!!!

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Permalink Reply by Thomas Richardson on June 1, 2010 at 11:08am

Thanks everyone for the info, Did normal oil check with burp and all was well.. Now have 1.4 hrs on engine with ground use and it is wonderful. During taxi tests the engine has run very cool, which I am extremely pleased with.. Ran fast taxi tests and the bad girl wants to leave the ground real bad!. Hope inspection will be in next few weeks and then she can go.

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