However, while recently doing a flight test program on a DA-42, I had an engine problem, so I flew it for help. I discussed the problem with the mechanic, and during this discussion, he pointed out a few of the characteristics of the Thielert which would allow a sudden stop situation to occur. They were soberingly simple.
There are many cases where I would want the failure to fail to a running condition, even if engine control, or condition were reduced. The notion that any one of a number of simple failures could cause the engine to stop instantly puts the occupants, aircraft, and the engine in much greater peril.
When the Thielerts work, they're wonderful. When they do not, it seems much worse that the much maligned Lycontinentals... I'll be interested to read the report on this one....
I to would like the benefit of DAR's knowlage on this subject, I can't think of an electrical problem that will stop the engine ( now they have the FADEC back up battery fitted) due to the fact that all the essential systems are duplicated.
There are mechanical issues that would stop the engine with a single failure but no more so than with an AVGAS engine................. Well so much for the theory perhaps DAR can enlighten us with some real world wisdom.
I am not at all an expert on the Theilert engine, so there could be fact which superceeds what I was told.... However...
Back in June, I was test flying a modified DA-42, including 64 3 minute climbs at various power settings. The right engine seemed to run okay, but at fulll power, as I slowed, and entered the climb, it's power would drop off. at 5000 feet, full power could drop as low as 83% load. when I sped up, it would come up a little, but not to the 100% of the left engine. So I took it for maintenance.
The Diamond service center mechanic gave me a bit of a tour around the engine (as he replaced the offending turbo waste gate controller). He showed me a two conductor electrical connector which was associated with the prop governor. He explained that sometimes the fork type female connectors in there would virbrate to have a larger opening. With this, the signal to the prop could be interrupted. He told me that even a momentary interruption in this signal would result in an instant engine shutdown, and no resart, unless the connector fixed itself.
He said that this was an example, and not the only one.
I really like the way the engine ran, but if that lower level of integrity is the cost, I'd rather have the Lycontinental for the cost....
The SMA diesel has a work around for this, so it will run without power or FADEC. I just wish tha SMA would fill the order I have placed for one!
Diesel and FADEC are the future, but we're not quite there yet....
Its back to the course notes for me to check that one out but I would be surprised if just one electrical connector malfunctioning would result in a total shut down, but your statement deserves further investigation.
All joking apart maybe it should have been an "O" instead of an E. but someone has saves 2 peoples lives here we could well be talking about a fatal. Don't care how much we practice PFLs its still a good piece of airmanship.
Remember that the person that owns the aircraft and the passenger that thinks he can fly.......!!!!!!!!!!!!