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excessive loss of oil during aerobatics

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Maxu
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Joined: Thu Sep 01, 2016 1:26 pm

excessive loss of oil during aerobatics

Post by Maxu » Tue Sep 06, 2016 10:46 am

Hello all,

I had posted this already in another mailing list, but haven´t got that many replies... so why not give it another chance here and start the discssions...

Last weekend I noticed an excessive loss of oil during aerobatics in our Extra (AEIO-580). Up to now we where using about 0.5-1 quart per hour of ADV style aerobatics, but last weekend that raise to around 4-5 quarts per hour (5 displays of around 15min each at an airshow). There is no visible (read "more then usual") oil coming from the cowling/firewall and I believe that if the engine oil would be burned by the engine (broken oil rings, bad valve guide or so) that there would be a noticable smoke trail coming from the exhaust with that amount of oil being lost!?

However, in one short video sequence I saw that after a negative push to the vertical there was quite a trail of oil coming from the engine breather hose, which I haven´t noticed in previous flights (at least not as intense as in that clip). I´m now suspecting the shuttle valve/air-oil separator...
Any hints, tips, tricks or suggestions?
Should I just remove both the shuttle valve and air-oil separator and clean/flush it with mineral spirits/petroleum?
Anything else to be aware of?

Thanks and best regards,
Markus

N23LZ
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Re: excessive loss of oil during aerobatics

Post by N23LZ » Tue Sep 06, 2016 11:01 am

With a sudden increase in oil loss, the shuttle valve is the primary suspect. I think you are on the right track

Maxu
MPF Student
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Joined: Thu Sep 01, 2016 1:26 pm

Re: excessive loss of oil during aerobatics

Post by Maxu » Tue Sep 06, 2016 12:11 pm

Thanks, I´ll check the shuttle valve and air-oil separator and post the results here.

Billyto
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Re: excessive loss of oil during aerobatics

Post by Billyto » Tue Sep 06, 2016 1:35 pm

My experience, if no oil consumption during ferry flights, the engine is Ok, and would look for the inverted system. Small oil leacks create BIG trails of oil with not much oil loss (Sukhois are a breed apart). I will concentrate on the inverted system. Anything more than 1 liter/hour of hard acro in a Lyco, should be investigated.....

Maxu
MPF Student
Posts: 9
Joined: Thu Sep 01, 2016 1:26 pm

Re: excessive loss of oil during aerobatics

Post by Maxu » Tue Sep 06, 2016 1:52 pm

That´s exactly what I thought would be the cause of the oil loss. There is no increase in leakage (a few drops here and there from the accessory case and the cylinderhead return lines, but I´d call that more "sweating then leaking") and I haven´t noticed any oil consumption druing a 3 hour cross country the weekend before...

As the plane is based about an hour away.... It seems to me the Christen air-oil separator can not be dissasembled for cleaning right? So the only thing to clean is to fill it with mineral spirits and give it a good shake?

Maxu
MPF Student
Posts: 9
Joined: Thu Sep 01, 2016 1:26 pm

Re: excessive loss of oil during aerobatics

Post by Maxu » Sun May 28, 2017 1:03 pm

I just wanted to share that the excessive oil loss which we had on our Extra last year has been fixed. We cleaned the Christen System and rotated the outlet of the air/oil-separator to face to the inside, rather then outwards. We are now down to around 4 quarts of oil in 20 ADV sequences (or about 0.5 quarts in 1 hour of aerobatics).

Unfortunately our engine has now developed an oil leak somewhere around the left magneto. It is not losing a lot of oil, bit it still seeps out the upper cowling so badly that I need to wipe it down after one sequence...

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