Thanks Scott,
If you are waiting for a definitive cause, you may have to wait for a long time. To me it is pretty clear that the lightening holes allow flexing with the power pulses that will eventually lead to stress cracking. Those cracks started at the lightening holes and propagated radially. That allowed escalating flexing that broke the ring around the mounting bolts.
My philosophy lately is that the best way to not have to re-do things over again, is to obviously over-do it from the start. Aircraft cooling systems are a good example. I also see having a little more weight in a flywheel as not too bad of a place to have weight. It will help with idle roughness, and help dampen power pulses - so I am not worried about a few more pounds up there. I even would have no qualms with adding several pounds and using the flywheel that Kelly found. If only that solution has an easy answer to the starter problem.
I have no desire to try another 13B plate. If so many of them are cracked and warped, there is a reason. They all started out new at some time. Inspection is not easy. It requires taking off the oil cooler, inter cooler, prop and spinner, oil lines to and from the gear box, then the gear box, then the damper plate, then the flex plate itself before you can do any quality inspection. It needs to be removed because you cannot see the mounting holes with the doubler plate in place. I am not interested in having something in my plane that reminds me of the reliability of a certified crank shaft :-)
Switching to an RX8 flex plate and adding an adapter (which will also add stiffness) only adds a couple of pounds. The RX8 plate is thicker metal (.09 instead of .08) and does not have the lightening holes that seem to have been at the root of my cracks. It is cheap ($160) and the ring gear fits perfectly.
I think Mazda was having problems with the 13B plate and that is why they beefed it up for the Renisis.
On Sun, Jul 17, 2011 at 10:31 PM, <shipchief@aol.com> wrote:
I just had another thought:
You might consider trying another 13b flexplate, but using a more comprehensive test for cracks before you put it in service.
Look the candidate flexplates over with a magifying glass, then, if they pass, use dye penetrant test or magnetic particle testing?
What I'm getting at here, is that your failed unit may have been flawed before you put it in service.
After finding a flex plate that passes, spend some time de-burring and polishing the stress zones based on the failed flex plate's cracks; that is to say, where you think the failures may have started.
-----Original Message----- From: David Leonard < wdleonard@gmail.com> To: Rotary motors in aircraft < flyrotary@lancaironline.net>
Sent: Sun, Jul 17, 2011 9:21 pm Subject: [FlyRotary] Re: Ok Here are the important flywheel measurements
That is not a bad idea while I have it all apart, as I have not changed them out yet. Inspection does not show anything that looks like a smoking rivet.
On Sun, Jul 17, 2011 at 2:17 PM, Tracy <rwstracy@gmail.com> wrote:
a kelly wrote:
.Did you replace the
aluminum rivets in your RD1X damper plate with steel bolts ?..............I seem to remember that
you did after several dampers (and yours) experienced alum streaking around the rivets...........
Just FYI to the group, the change I settled on for the damper rivets was to use -AD rivets instead of -A. The tensile strength is about 3 times higher on the -AD.
Tracy Sent from my iPad
.Did you replace the
aluminum rivets in your RD1X damper plate with steel bolts ?..............I seem to remember that
you did after several dampers (and yours) experienced alum streaking around the rivets...........
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