Sport Pilot Talk

Greetings everyone, I'm still keeping my eye on the used S-LSA market and have noticed a trend that some aircraft barely have 100 hours (and some others only have 200-300 hours) that are under 10 years old, and it makes me wonder if the standard 100 HP dual-carb Rotax engines have any known problems from LACK of regular use (e.g., internal corrosion)? I've watched youtube videos that showed that air-cooled GA engines can develop corrosion issues with lack of use such as pitted camshaft lobes and spalling on crankshaft bearings, both from inadequate lubrication in what are essentially storage conditions. Also, are there any particular years (within the past 10 years) that have proven to be particularly problematic with this Rotax engine, and if so, are there issues that stand out? Thanks!

There are some gig differences between Rotax and the legacy aircraft engines. The biggest issue with internal corrosion is moisture in the crankcase. The legacy engines have a breather that is open to atmosphere, and can draw moisture into the crankcase. They also have steel cylinder walls that can rust. Just like the crankcase they can pull air in through the exhaust and intake allowing for exposure of the cylinder walls to moisture.

Now the second thing I mentioned above also applies to Rotax, except their cylinders are ceramic coated aluminum. These don't rust. The crankcase is also not exposed to the atmosphere because the breather is on the oil tank. The oil in the oil tank provides a seal that prevents moisture from entering through the breather.

I am not going to flat out say that Rotax can not get any damage from sitting, but it is nothing like a legacy engine. In the almost 15 years that I have been messing with them I am unaware of any that have had issues from inactivity. I should also add that Rotax does have a process for engines that are going to experience long periods on inactivity.

Siddhartha wrote: ↑Fri Mar 19, 2021 4:39 pm are there any particular years (within the past 10 years) that have proven to be particularly problematic with this Rotax engine, and if so, are there issues that stand out? Thanks!

Not in the past 10 years, but here is a known issue with the pre-2006 engines, prior to crankcase (not engine) s/n 06.0010. These early engines are prone to chafing at the crankcase half joints. First symptom is oil leaks at the split in the case.

Those early engines have a 1500 hour TBO (which they might not make), and are not eligible for the SB raising TBO to 2000 hours.

If you want to see the exact nature of the failure mode, take a look at my recent webinar "Pushing Past TBO", at:

http://avsport.org/webinars/videos/past_tbo.mp4

drseti wrote: ↑Sat Mar 20, 2021 10:47 pm

Siddhartha wrote: ↑Fri Mar 19, 2021 4:39 pm are there any particular years (within the past 10 years) that have proven to be particularly problematic with this Rotax engine, and if so, are there issues that stand out? Thanks!

Not in the past 10 years, but here is a known issue with the pre-2006 engines, prior to crankcase (not engine) s/n 06.0010. These early engines are prone to chafing at the crankcase half joints. First symptom is oil leaks at the split in the case.

Those early engines have a 1500 hour TBO (which they might not make), and are not eligible for the SB raising TBO to 2000 hours.

If you want to see the exact nature of the failure mode, take a look at my recent webinar "Pushing Past TBO", at:

http://avsport.org/webinars/videos/past_tbo.mp4

Actually the old style crankcase ran into mid 2006.