fluid volumes

[hallschuch]

I am finishing building a series 7 kitfox with the rotax 912 ULS, the rotax manual describes the oil volume of the engine to be about 2-1/2 liters... but I dont know what that equates to witht the oil cooler and plumbing, same with coolant --- anyone know those numbers?
thanks!
Karl

[Dave S]

Karl,

I have the ULS with oil cooler - between the filter, cooler and hoses as installed, I end up using 3 L - but put the last 1/2 L in slowly between checks - exp aircraft can be a little different.

[jiott]

Ditto to Dave.

[hallschuch]

Karl,

I have the ULS with oil cooler - between the filter, cooler and hoses as installed, I end up using 3 L - but put the last 1/2 L in slowly between checks - exp aircraft can be a little different.


Thanks Dave!

[hallschuch]

Karl,

I have the ULS with oil cooler - between the filter, cooler and hoses as installed, I end up using 3 L - but put the last 1/2 L in slowly between checks - exp aircraft can be a little different.



Dave, as ;ong as I have yor attention perhaps you can shed some light on the coolant levels -- the installation manual calls for 1.5 liters but that seems to not fill the system at all -- in fact it seems to be able to hold twice that amount... any ideas?

[Dave S]

Karl,

My observation is that the first fill always comes up a little short - that is pretty typical.

When the coolant system is filled after it has been empty, there will be a few dead spaces within the system which will trap some air until the engine is run and the circulation displaces the offending trapped air. For instance, the radiator - any space above the top of the outlet elbow will not fill - the same thing with the heater core. There are likely a few nooks and crannies in the cylinder heads and upper cylinder hoses that will also capture a little air as the coolant seeks its level when the coolant is not circulating because the engine is not running. Might depend a little on the level of the fuselage too - trigear vs tailwheel might create some minor temporary air domes that are different in each case.

Also consider that not all aircraft will have the identical coolant capacity - with or without a heater and the length of the large hoses can change that a little.

Not to be concerned, When the engine runs the first time the circulation will purge a lot of the air after a few minutes. It won't "air lock", the coolant circulation will take care of it.

On a cooling system refill after draining. I don't even think about the design volume, simply fill it till expansion tank is full to the the cap seal area. Make sure the overflow bottle is about 3/4 full - run the engine for 5 or so minutes, shut down and recheck - usually the first cycle displaces a lot of the air - check and refill as necessary to bring the level up again. A second run at a higher RPM (so the coolant circulation is more enthusiastic and will catch a little more of the trapped air and expel it.) Then doing a good warm up on the ground followed by a shutdown and leaving the pressure cap alone will usually suck more liquid into the system as as the heated coolant contracts with cool down. A lower level in the overflow bottle indicates the engine has pulled some additional back and is an indication of stability when it quits doing that. Keeping an eye on the CHT guarantees you are safe from overheating.

After this I like to recheck the level before each engine start till I am assured that it has stabilized.

Hope I didn't make a short story too long:o

Cheers,

[hallschuch]

Thanks Dave, I really appreciate you taking the time to detail everything -- thanks very much!