Yes, reading it again it really sounds strange:
The bad news is of the few we found with issues,
neither our engineering team or our metallurgy specialists were able to define a
consistent root cause of the issues
It just sort of disintegrate ?
A hangar neighbour friend had already had to send his engine (IO-400 on a Glastar) back to Superior a few weeks ago. They paid for shipping, but not for the work to remove it.
He got the notice that it was being bought back just before the public announcement.
Although they will refund the engine cost. He now needs to find a replacement that will work with his exhaust, cables, baffling, cowling etc.
It also means a rather extended AOG period while it’s all sorted.
Although it’s commendable that they are taking the issue seriously, it seems odd that they can’t offer a fix, even if it involves some de-rating.
Does the IO400 share dimensions with another more common engine?
The other angle is that AIUI a US Experimental owner can just disregard this recall. They probably don’t want to, of course…
Does the IO400 share dimensions with another more common engine?
It’s identical to a Lycoming 360 except the longer stroke. Doesn’t Lycoming have an experimental 390 or something? There are other manufacturers also, Continental makes them as well.
Of course in the minor details there may be differences, length off cables etc.
I am told by a US shop which builds a lot of Exp engines that 9:1 pistons still work with 91UL and have no impact on engine life (the context was the IO540-C4 with the standard 8.5:1 pistons). 9.5:1 need 100LL and shorten the engine life.
There is a certified IO390 but it was never certified for 91UL which is one reason why Pipistrel dropped it for the Panthera project.
Just checked. Lycoming do have the Thunderbolt 390 (exp).