In early May 2023, there was an accident with a Rans S12 powered by a UL520T. Preliminary accident report available here.
As stated in the prelim accident report, the engine had been experiencing high CHT temperatures on one side of the engine and the builder had increased the size of the oil cooler and was working on overall cowling / cooling issues. No reports of high oil temperatures are present in the prelim findings.
I have talked to the US Distributor and other builders about this accident - which is very concerning. A crankshaft failure is not something to be taken lightly.
I am not going to get into relaying what I have heard about the circumstances around this incident - although there appears to be extenuating circumstances. The crank failure was most likely a result, and not necessarily the cause. But the nature of what started the failure chain are not yet known.
Bottom line: I am going to wait for the 'final' report before making any decisions. The week of June 19th, 2023 the NTSB is going to perform an detailed analysis of the crank and case with the assistance of the US Distributor. The factory is fully cooperating with the investigation.
This is the first crankshaft failure of any UL engine.
More questions than answers at this point.
I am going to continue forward on the build, but spend as little money as possible on the engine side of the install just in case I have to abandon it. I truly hope that is not the case, but a definite possibility. Flying behind an engine you do not trust is not a happy feeling.
