I think the significant difference is that the Ventus cM does not have a
rigid propeller, but a foldable 2 blade Technoflug prop. This installation
has been in use in 100+ gliders since 25 years without propellershaft
problems, I think this is one of the SLG's with least trouble.. Also the
2350D has the same prop shaft part number, but installed with the 5 blade
foldable turbo propeller, these also have no problems. The newer
installations in DG1000T and Antares18T uses a conventional rigid
propeller, so I suspect the problem is that the prop has much higher
inertia in the "bending" plane of the propshaft.
I don't know which the other aircraft type is, but my bet is the Antares..
If they'd just known about all these ongoing problems, they should have
shifted to the Ventus prop..


At 16:42 24 September 2015, NG wrote:

Apparently another variant of the 2350C or the Solo 2350C has recently
deve=
loped a vibration problem in another aircraft type. DG has recently
posted
=
the following message regarding the delay in resolution of the current
prob=
lem with the DG1000T Solo 2350C as follows: "The complexity of the whole
p=
roblem is also reflected in the fact that a defective vibration behavior
at=
the propeller shaft has also been found by another manufacturer, and
also
=
in this case, extensive tests and measurements are necessary". The full
st=
atement can be found @:
http://www.dg-flugzeugbau.de/index.p...t_news%5D=3D3=
06&cHash=3D12e753b242eed326665097dbe7ab3ed3
So you may want to make sure that this is not an issue with the Ventus
CM.
=
It is unclear from the DG post because the "another manufacturer" is not
s=
pecified.

That said, I think it is hard to make an argument for reliability of the
en=
gine when 3 consecutive airworthiness directives by EASA and the FAA have
e=
mergently banned the use of the engine over 3 consecutive gliding
seasons.
=
In my opinion, the levity of propeller departure, either on the ground
or
=
in the air, should not be diminished by arguing that your engines have
alwa=
ys started. That is not the point. =20

In fact our Solo 2350C has NEVER failed to start. The issue we have had
wi=
th it is that it won't stop when the ignition is turned off. Our IA/A&P
wh=
o is highly experienced, has not been able to solve the problem. Not
stopp=
ing would not even be that serious of a problem but the engine has
attempte=
d to stow itself on multiple occasions, while still running. This is a
rec=
ognized problem and resulted in DG service note No. 73-11 which states
the
=
following regarding a "run-on" situation: "If this happens the engine
will=
retract further and propeller stopper will collide with the rotating
prope=
ller." Which it has. This is an unsavory situation either in flight or
on=
the ground. =20