JUGFLIER

Hey guys i need some help. I have two DA50s one on a new Carden Yak from Hamger 9 that my son worked three weeks to get the money to buy, and an Aero works extra 260. We went to the Tuscaloosa Al. fly in today and both engines broke rings in them. My son was hovering his Yak when the engine died and resulted in the total loss of the plane. ( this was the fifth flight on it.)

I was actually flying higher and was doing some circle flying with a few tumbles to go with it. I had just enough altitude to make the runway. I was swingsing a vess 22-a and my son was swinging a vess 23-a.

We followed the breakin procedure on both engines and ran over 2 gallons of ashless then we switched it over to Amsoil. We mixed the Amsoil to about 50 to 1. Both engines have around 4 gallons thru them and are about a year old.

Has anyone else had this problem? Oh, and by the way these aren't my first gassers, i have several, and they were not too lean.

I was also told today by someone who does a lot of flying that Desert Aircraft had taken Amsoil off it's list of approved oils. Anyone heard that?

AirWizard

My Feedback: (3)

Could using the Amsoil at 50 to 1 instead of 100 to 1 caused the rings to break?

Jezmo

It's possible that the engines were running too hot and caused the ring end gaps to butt together which will cause them to break. I can't imagine the Amsoil being the culprit.

krayzc-RCU

My Feedback: (31)

bummer

JoeAirPort

My Feedback: (41)

Holy smokes, they failed the same day within minutes of each other? Now that is a coincidence.

altavillan

My Feedback: (1)

Kinda sounds like it was gas left out in the sun too long and cooked off the good stuff. Then when running the engine the heat went way up along with some pre-ignition causing the failure mentioned above.

JUGFLIER

Alta,
It was fresh mixed gas, less than a week old. Also i have an enclosed trailer so it wasn't in the sun.
Thanks.

krayzc-RCU

My Feedback: (31)

your rings my end up being a bad batch or lot numbers once you have a chance to send those motors in to DA.

JUGFLIER

This is my suspicion. This is why i was wondering if anyone else has had this problem. I can tell you we take care of our equipment including the engines. I balance all my props. If my fuel is a week or two old i usually get fresh and run the old stuff in my weedeater, i have lots of weedeating here. We had the engine on the yak has a huge round open to the front cowl, there was no issues with cooling on either plane. I have cut a huge hole in the bottom of my extra. We are not doing anything with these engines that everybody else is not doing. We are doing basic aerobatics with some harriering and hovering added in. When mine quit i was flying in a circle and pulled up in a hover and then went full power and full down and flipped the plane end over end about three times and pulled out. as i was about to pull out i came off the throttle to slow the planes inertia and as i throttled up to fly out the engine quit, broken ring.

JoeAirPort

My Feedback: (41)

I think a guy at the field told me that he mixed Saber at much more oil than 100:1 and he stuck a ring. Although this would only be one possibility. There are many things that can cause a failure. And for both to stick the same day....sounds like a defective batch of rings.

nonstoprc

My Feedback: (90)

I was advised by DA not to use a rate lower than maybe 90:1.

edgeman55

My Feedback: (25)

My Da50 with KS tuned pipe has 40 gallons thru it and never has missed a beat.I broke it in on Lawnboy at 32/1 for 4 gallons.Now run Mobil MX2t at 40/1.Engine turns 7300 with a Vess 23A at 5000 ft elevation.I would send them back to DA and they will fix them if it was there problem-best service in the hobby.Sorry to hear your son lost a plane because of this but hard to figure that both had bad rings,sounds to me like they over heated because of wrong oil mix or bad tuning.

JoeAirPort

My Feedback: (41)

I also run that MX2T in my engines. It's pretty good stuff. I run it 32:1 in my ZDZ 50 NG and 50:1 in my Brillelli 60.

When I had a DA 50 I broke it in with Lawnboy and then went to Saber 100:1.

AirWizard

My Feedback: (3)

I'm not an expert by any means but have been told by some knowledgeable people that mixing saber amsoil at 50 to 1 will cause your rings to stick.

tkilwein

I Also called DA on 80-90% ratio last year and was told, IT WOULD STICK A RING over time.
They said nothing less than 90 to 1 with amsoil, and recommended 100 to 1.
At 90 to 1 they said I or them would be taking engine apart over time to clean the ring groove.

JUGFLIER

Exactly what is meant by sticking a ring? Does that mean it would stick closed and make no compression or that it would stick out and hang the exhaust port and break?

tkilwein

The ring grove/ring will get a build up on and that then reduces or eliminates the clearance of the ring to ring grove in one or two directions. this binds/restricts the movement of the ring. In car engines I have seen where the ring sticks closed inside the groove and also where the build up behind the ring prohibits the ring from closing in and has excessive ring/sleeve wear. For car engines I have a piston ring reamer to clean up the ring groves when I clean them if using the same pistons. I have had a few broken compression rings not oil rings due to carbon build up in car engines.

altavillan

My Feedback: (1)

Generaly, "sticking a ring" means, enough carbon has built up in the ring groove to prevent it from moving around and following the shape of the piston. Fatal cylinder wear will occour shortly after the ring sticks. Sticking can occour at any time however. If there is enough carbon and oil riding in the ring groove and the engine is made to go passed crittical heat, the oils can turn to carbon quickly and stop the ring from working.
I mentioned your gas could have been allowed to sit out in the sun the day your engines failed. Octanes and burn volitals can quickly vent off from the fuel when left in the sun on a hot day. I would say 1 hour in the sun sitting on hot asphault will knock 91 octane gas down to about 80 octane. 80 octane gas will burn much more violently than 91 octane. It will also start finding the hot spots in the combustion chamber and start a preignition cycle and concentrate massive heat in that spot. Typicaly where the gas exhausts with our two cycles. That heat can transfer to the ring and start the sticking, and in very short order cause a failure in the engine. If I had your engine in my hand I'd look for an odd wear pattern where the ring has been riding in the cylinder.

JUGFLIER

Thanks Alta, Since my engine is less than a year old i am not going to tear it down, i'm just going to send it to DA.

BTerry

My Feedback: (8)

Jugflier was using Amsoil Dominator, which is made for 50:1 ratio. DA was referring to Saber which is for 80:1 to 100:1.

hutchi

Back of Saber bottle says 50:1, 80:1, 100:1, I;ve been using the 50:1 in a bme 115 is this wrong?

rc-plane

I am about to buy a DA....Well actually already told them I wanted one but they ran out so they are building them. So if you find out anything PLEASE let me know before I get it!

Thanks

altavillan

My Feedback: (1)

More oil will not hurt if you understand that some synthetic 2 cycle oils do not burn under normal combustion heat, unlike oils similar to pennsoil. However if you run your engine too hot you will cook the synthetic oils into a hard carbon glaze, and then the excess oil will deposit much faster than a leaner oil mix. If you are not comfortable running your engine at leaner mixes maybe you should look around for a different synthetic oil. I've been using a synthetic oil in my 115 that mixes at 114 to 1 but I usualy go about 90 to 1. My first 115 blew a cylinder from pre-ignition at around 400 flights. My fault. There was a normal amount of black carbon build up. The rings were free and clear.

JUGFLIER

With the muffler off the engine you can look into the exhaust port with the piston down and see oil all over inside the engine. It is being well lubed. I dont think the rings stuck in either motor. They look as if they just broke, they did not fall out, they just protrude into the exhaust port. The engine will still turn over, it just clicks when the ring goes past the exhaust port and there is no compression.

AirWizard

My Feedback: (3)

It will be interesting to hear what DA says.