I have ordered a new carb flange to replace the one that split. I just used the
part number off the flange, but have since seen the service bulletin showing
there is a new design part. The problem I see with the flange that broke is that
it is a solid rubber part with no internal reinforcement. On Lycoming intake
tubes and every cooling hose I have ever seen, there is a fiber reinforcement
to prevent what ended up happening to me. The crack started and then easily
propagated around 180 degrees, letting a huge amount of air to the intake
manifold.
These flanges should be made of similar rubber. I am hoping that when they
send me the new one, it will be the new part number. I would assume they would
not be selling any more of the old design, since the service bulleting calls
for that to be replaced. The service bulletin also says to replace both flanges.
This is really a Mickey mouse design, as far as I am concerned.
In addition to the flange material, the airbox should really be supported, since
the entire airbox assembly in cantilevered on those flanges, support out at
the airbox would reduce the load on the flange. I have seen the installation on
the Stemme motorglider and they have the airbox resting on rubber blocks. I
am going to figure out a way to make the same sort of arrangement on my airplane
as well.
As far as tightening the flanges, that is also a weak point in the design, since
there have been cases of the carbs separating from the engine by being too
loose.
Not too tight, not too loose - just right. It shouldn't be that sensitive.
That's enough of that
Dave
A227
mini U2
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