The thrust washer (plastic washer) failed inside the gear box and went through the motor. I had the gear box overhauled at 1000 hours but at that time rotax was not requiring that the thrust washer be replaced, since January 2023 they now require this washer to be replaced with a gearbox overhaul at 1000hours. These parts were also not previously cooled/oiled, on all the new rotax engines they changed design to now cool/oil these parts off the shaft. I do not know exactly when this change was made, I believe it was on version 2 or 3.

good you?

That will be tight, there are cross bars on the ceiling of the aircraft that your head will bump into. My headset will hit these in the winter when the seat is stiffer, and I'm only 5'10''.

@@DarrylZubot Thanx for the update. How you grade this plan for use as a sport plane trainer for high school age students.

Awesome airplane for high school students. They'd love it.@@SulaimanTheAviator

Hey there, this is a virus sw, not a sinus aircraft.

That should be fine yes, with headwind definitely should be okay.

I recently replaced the engine, has the same oil pump, same radiator size, same oil line setup. I have almost no oil pressure drop with altitude climbing with this new engine. Something was not right with my original engine that was causing oil pressure drop.

About 127knots. But you should never cruise at 4800rpm that’s too low. Cruise at 5400 as the engine is designed to run at

@@DarrylZubot :O what is pipistrel 75% rpm and what is max rpm and what is 5400 cruise speed? I am flying Viper SD4 with the same engine cruise is 4800 and maximum is 5500 more than 5500 for five minutes so In my SD4 is 4800-5000 optimal in bigger rpm is aircraft "nervous" :D So what is your consumption in 5400rpm and speed do you have IS engine? Thank you for reply I know a lot of questions but I am thinking about buying pipistrel sw121 or tecnam 2008JC.

@@okuliarerayban9481 speed is 130knots and 15l/hr fuel burn with 5400rpm. Read the forums about cruising rpm’s with 912 engine. It is recommended to be at about 5300-5500rpm for cruise no matter what aircraft you have. Engine is not designed to run at low rpm but it’s probably okay. Max rpm is 5700 for take off on pipistrel.

@@DarrylZubot I have in flight operating manual 4500-5500

They really are!

What was your engine time when yours failed? I’m told it used to be a metal washer but when it failed it completely destroyed engines. Not sure why they have a part in the gear box that is prone to failure in the first place

@@DarrylZubot In all my years of being an aircraft mechanic, I have never heard of a washer "failing.". Is there a service bulletin or an AD on this thrust washer ?? Seems really dumb to have a powerplant failure over a washer !! Is this only on 912iS ?? What about 912 ULS ??

@@mustardseedsociety it sure is dumb. No AD regarding it. I’ve heard from several people now that have had it fail prematurely. I’m told rotax has quietly changed engine design to include a sprayer to lubricate these parts in the gear box and it should be a non issue now on newer engines. Sounds like it is mainly an early version 2 912iS problem. Not sure why this is. The strange thing is they have an overhaul time on the gear box which I complied with but found out that at the time of my overhaul it wasn’t required to replace this $2 plastic washer. Rotax has changed its overhaul to include replacing this washer now since Jan 2023.

@@DarrylZubotWhat I can't figure out is why does a washer needs to be lubed in the first place ?? Is it a moving part ?? I only found one video on the Rotax thrust washer - a guy from Australia was installing one on his Rotax gearbox and he had to put Locktite on the nut, then he puts a pin in the engine so the crankshaft won't turn, then he torqued the nut {against the thrust washer} and the torque wrench broke. Then the video ended by him saying he needs to take the nut back off and start all over. So needless to say, I did not get the answer I was looking for. I think the biggest mistake he made, is he was not ready to torque the nut after he applied the Locktite to the nut. He applied the Locktite but then he had to go find the socket for the nut. You have to torque it while it's wet. Plus I don't think he had the torque wrench set correctly. What aviation needs are the aviation equivalent of "Engineering Explained" - a popular You Tuber who makes amazing videos explaining how cars work. Very hard to find these aviation equivalents on You Tube. Too many "look at me - I can fly a plane" videos. Even those videos are frustrating because the pilot rarely gives true airspeed numbers which always frustrates me !! With the exception of Baron Pilot and Matt Guthmiller.

I saw that video you are talking about. So I'm told Rotax added hole in the shaft that sprays the sprag clutch to lubricate this part, maybe it overheats and degrades the plastic washer? I have no idea why or how these are failing. But it sure seems like Rotax knows about it and did a change to the engine without notifying previous owners of this potential failure. This could cause accidents, I had to go to idle right away as my oil temp was at 135º, pressure dropped, and my hydraulic prop was surging due to lack of oil flow so I had no choice but to land right away, luckily it happened when it did and not when I'm 300km from an airport over Northern Alberta forest.@@mustardseedsociety

It used to be metal I’m told and when the metal washer failed would be a bad situation. But I’m not sure why they have a part in the gearbox that is prone to failure. I’ve heard from several people now that have had this washer fail.

@@DarrylZubot the longer you own a rotax the more design flaws you will find. After 7 years I don’t think they are comparable to a real AC engine. Very few A&Ps will work on them. SO many issues just like yours. Fairly pissed at Rotax for putting these engines out with so many design flaws… oh and they are just as expensive to overhaul as a continental so ur not saving money. Parts are insane for these snowmobile engines. Rotech Motor has abandoned me as a customer… thanks guys! Really making rotax look like a shit company.

It is

Haha yup they are pretty bad. Thanks I think so too

About 5-7 knots

Hey. Definitely the fuel injected 912iS. Have a friend with 912ULS. He got fed up balancing the carbs that he converted it to fuel injected. It’s much smoother engine, less maintenance, better fuel burn, auto mixture. I’ve had zero issues with it after 1500hours.

Hey there, I had an oil pressure issue not oil temp. I installed large diameter oil lines and fittings to improve the loss of pressure as I climb

@@DarrylZubot Actually, look back at your videos. Your oil temperature is 120C or more! What happens at this temperature is the viscosity thins and the pressure drops. I have high oil temperature on my 912ULS and I can't figure it out. Its frustrating

@@PilotJimmyJ that has very little effect on this issue. I’m flying at high altitudes with cold oil temps and my pressure drops. You are right it will have some effect but it’s not reason why it drops. I am told now by rotax Austria and others that the pump is just too small to maintain oil pressure with constant speed prop, and having oil temp regulator increases oil lines further reducing pressure from pump.