Kitfox4 with rotax 912ul

Hi All

The 5 year is called out due to the ageing of materials of the "rubber" type parts.  Some parts are encapsulated, such as inside the crankcase, and not subject to this.  Others suffer from deterioration due to exposure to sunlight or fuels.  

As for electronics on a Rotax there is no lifetime and all the parts can be run on condition provided that they meet the standards at overhaul  There air some exceptions such as high tension wires and spark plug boots that should be changed at TBO.  

The most likely failure in the electrical system is aging and deterioration of the wire coatings.  The wires from a 20 plus year old engine an start to shed the skin.  They can also be in areas of accelerated wear such as a hot engine bay without adequate airflow.  As Eric has pointed out there are some components that can fail such as capacitors.  The most common in my experience is from pre 2000 wire coatings on old engines.  I have seen them crack and short, some will become soft, it all depends on the conditions they are stored, used and installed in.  You have to do a good inspection..  Do a good check every annual, especially on engines that are old.  Don't think of it in hours, think of the time in calendar months for a lot of your electrical issues.  

There is a service information on storage and for anyone with an injected engine there is a particular note to pay attention to.  The ECU has to be run for a period of time even if it is new in the box sitting on a shelf every 2 years.  This would also apply if you have it sitting in a hanger for that period of time.  It is much better to use it than let is sit.   This is a requirement to ensure that the internal parts function as normal.  

Cheers

reference Service Letter re storage

SL-916 i-003R2 / SL-915 i-003R3

SL-912 i-011R3 / SL-912-022R3

SL-914-020R3 / SL-2ST-014R3

Hi Eric,

Thanks for the above comments. All sounds a bit grim, had always thought that stored/unused electronics laster pretty much forever, subject to no external negative factors - high heat/moisture/chemical/etc

My last 912 ULS was about 20 years old, Hobbs 950 hrs, when I sold the aircraft - no sign of ignition module failure/deterioration - Good luck???😈

This post and 98% of the previous posts by this name were made by me, Bert Shivers. I still help maintain and modify the airplane. I mention this only because as I worked with engine issues when I owned it, I was a member of this forum and received a lot of guidance and help. You asked what you might look out for, so if interested, I think you can look up posts by my name.

In case the point I originally hoped to make was not clear, I will be blunt. If one does not know what to look out for (concerning Rotaxs, I did not), one does not know if a purchase is a bargain or a liability. One is wiser to pay a disinterested, knowledgeable person to do a prebuy.  My opinion and probably worth what you paid for it.

If this were me, and I liked the airframe condition, I’d ask the seller to price the aircraft without the engine. According to the Rotax maintenance instructions, that engine requires a complete tear down inspection at an authorized Rotax Service Center. As others have noted, numerous items will require replacement based on the calendar or to comply with the dozens of Service Bulletins that will apply to this engine. The cost will be significant, likely reaching the cost of a new engine.
If one were to decide to buy it, get it running, and just fix problems as they appear, don’t carry any passengers. That EXPERIMENTAL placard won’t protect you from any injury lawyer.