Rotax 912 S - OIL Level and reservoir

[GR8-DAD]

I only fly my plane over weekends and everytime I do my pre-flight from the previous weekends flying the oil level in my reservoir shows empty cause all the oil has drained back into the sump.

I am supposed to manually crank the engine a couple of times with the prop to get the oil back into the reservoir but have found that this does not work - I always end up cranking the enigine with the starter (mags-off of coarse) for about 20-30 seconds before the oil level indicates correctly (the correct amount of oil is in the engine).

This procedure is not only timeous, but also potentially dangerous - you have heard of Murphy.....

Any ideas or is this normal? Morph suggested that my oil reservoir might be mounted to high, causing the oil to siphon back

[Mogas]

GR8-DAD I have similar problem though mine does not drain away completely. This is what I do, probably not the correct way but works for me.
I always hand prop through about 6 compressions to check for hydraulicing in the cylinders when I get there in my walkaround.
If I have not flown for more than a couple of days I will start her up paying very close attention to the oil pressure, turn off after about 20 seconds and then check the oil level. I don't like the idea of cranking away with my starter for so long.
AFTER flight I check oil level and if I am flying again soon say that afternoon or next morning I simply check for leaks by having a good look in the bottom of the cowling, do my prop pull throughs and thats my oil preflight done.

[Griffin]

I always hand prop through about 6 compressions to check for hydraulicing in the cylinders...

What is "hydraulicing "

[Mogas]

If more than just a little bit of oil has found it's way into the cylinder on top of the piston it will cause damage if run or even cranked in this condition. On the compression stroke the oil unlike the normal fuel/air mixture does not compress and will probably bend the con-rod.

[Griffin]

Ahhh. So the symptom would be that you would not be able to turn it through the 6 compressions.

[GR8-DAD]

Thanx Mogas, I like your idea. I future I'll do a couple of manual crankings and then start immediately.

Can I ask you a few Q's though since you also have a BB and I would like to get more info from other similar planes.

a. What is your max rpm that you reach on take off? (mine 4950 rpm)
b. what is your 75% cruise rpm (mine at 4300 rpm, but I think it is too low, not optimizing engine torque and power curve - due to prop pitch setting, cruising at 93 mph at 4300 rpm)
c. Fuel consumption?

Thanx and cheers.

[Mogas]

GR8-DAD
I have inflight VP, for best climb performance I set take off pitch to give me 5700, soon after rotation and positive rate of climb I pitch it back to 5100 but leave throttle wide open.
At gross weight 500kg, 97 mph, 4900 rpm my fuel flow indicates 17 litres/hour.
If I am one up and just going nowhere slowly 70 mph, 4500rpm, 12 litres/hour.

[Morph]

Which Variable pitch prop did you install. I am putting in an IVO 72" 3-blade VP

How are you measuring your fuel consumption. YOu mentioned you had a return line on the fuel so a fuel flow meter would not give you an accurate reading

[Mogas]

Morph, disregard the pm, refreshed the page and can now post reply.
Prop is a Woodcomp Vario 2 blade, works with a crank handle which pulls a cable for course, acting against a spring in the hub which tries to push it fine. This prop type was standard on the Samba, don't know if the Samba XL has a different prop.
Yes, there is a discrepancy with my indicated fuel flow. I use the ff as a trend indicator rather than to work out my actual fuel burn.

[GR8-DAD]

OK Mogas, this is how it works. The only thing that prevents your aerie from qualifying as a very nice aerie is ................


.... ..it's not based in Cape Town..

Must admit, the taildraggers are so much more gracious that the tri-gear's. considering changing mine to tailie as soon as I master the art.
Thanx for the info.

[Mogas]

Thanks GR8
I can highly recommend the tailie conversion. Check out my post about the locking tailwheel, a little bit of labour but simple to do.
Regarding the flying, converting will probably not be as hard as you think, found mine so. Now it is easy to have safe landings, the trick is to make them safe AND gracefull, keeps me occupied for hours, great fun.