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charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sorry to chime in - i remember on Paul Lamar group way back they talked about the cracks on the forum Think it came from =E2=80=9Cgyro=E2=80=9D forces Get Outlook for iOS ------------------------------ *From:* Rotary motors in aircraft on behalf of Andrew Martin andrew@martinag.com.au *Sent:* Friday, January 10, 2025 7:49:19 AM *To:* Rotary motors in aircraft *Subject:* [FlyRotary] Re: Flexplate cracks Maybe some of the cracking flexplates are resulting from starting issues, the starter motor can hammer the ring gear if not meshing correctly or if engine misfires on start. may explain why so many flexplates come pre-cracked from the wreckers. Andrew On Fri, 10 Jan 2025 at 11:32, Stephen Izett stephen.izett@gmail.com < flyrotary@lancaironline.net> wrote: Hi M I was wondering the same thing. What I discovered first of all was that flex plates are designed to flex (funny that) and cracking is not limited to our setup. There are companies that specialise in stronger flex plates, particularly for modified and higher horsepower engines. Since our engines are being used at a higher horsepower per unit time and therefore higher stress (assumption) perhaps our setup could be likened to race applications. But then our hours of use would be significantly lower (assumption) than an average vehicle, but perhaps not a race application. Is the cracking we are seeing consistent with race applications? But they dont race automatics, do they? So my take on this is that perhaps the flexing of the plate in our setup is to some extent higher than OEM. Our options seem to be: 1. Replacing the OEM flex plate with a stronger part. Steve B being the latest going down that track and in his case also removing the rubber isolation in the process. 2. Connect direct to the eccentric shaft and therefore taking the stress off the Flex Plate doing away with the damping mechanism which Tracy did, and perhaps is still doing. Would be real nice to know. Like M, I would appreciate hearing what others know or are thinking or doing. Steve Izett > On 10 Jan 2025, at 2:15=E2=80=AFam, Marc Wiese cardmarc@charter.net < flyrotary@lancaironline.net> wrote: > > Has the cause of these cracks been uncovered, and if so, what is the current thinking on it? An AL racing plate? > M > Sent from my iPhone > >> On Jan 9, 2025, at 1:31=E2=80=AFAM, Steven W. Boese SBoese@uwyo.edu < flyrotary@lancaironline.net> wrote: >> >> =EF=BB=BFSteve, >> >> I didn=E2=80=99t see the cracks prior to disassembly and doubt that they= could have been seen on the counterweight side very well -if at all- when assembled. >> >> I replaced the Flexplate with a steel flywheel about a year ago. Since then, I replaced the four rubber dampers with machined aluminum discs giving a solid connection and then dynamically balanced the system. This was done because maintaining a dynamic balance wasn=E2=80=99t possible with= the dampers. Only a few hours of flight have occurred in this configuration so far and there has been no indication of problems resulting from this change= . >> >> Steve Boese >> >>> On Jan 8, 2025, at 11:03=E2=80=AFPM, Stephen Izett stephen.izett@gmail.= com < flyrotary@lancaironline.net> wrote: >>> >>> =EF=BB=BF=E2=97=86 This message was sent from a non-UWYO address. Pleas= e exercise caution when clicking links or opening attachments from external sources. >>> >>> >>> Hi Steve >>> >>> Is this recent then? >>> >>> I=E2=80=99m not able to get to my aircraft at present to check my flex = plate which has probably seen 50 hours of service. >>> >>> Was it possible to see these cracks assembled? >>> >>> I would appreciate your reflections on Tracys latter choice to remove the damper, and particularly when using a timber/glass prop such as an MT. >>> >>> It would be great to have an update and current info from Tracy regarding his no damper hours if anyone can contact him. >>> >>> Very helpful, thanks again Steve >>> >>> Steve >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html --000000000000963ebf062b5a216e Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Sorry to chime in - i remember on Paul Lamar group way bac= k they talked about the cracks on the forum
Think it came from =E2=80=9Cgyro=E2=80=9D forces

Get Outlook for iOS=
From: Rotary motors in aircraft <flyrotary@la= ncaironline.net> on behalf of Andrew Martin andrew@martinag.com.au <flyrotary@lancair= online.net>
Sent: Friday, January 10, 2025 7:49:19 AM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: Flexplate cracks
=C2=A0
Maybe some of the cracking flexplates are resulting from starting issu= es, the starter motor can hammer the ring gear if not meshing correctly or = if engine misfires on start. may explain why so many flexplates come pre-cr= acked from the wreckers.

Andrew





On Fri, 10 Jan 2025 at 11:32, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
Hi M

I was wondering the same thing.

What I discovered first of all was that flex plates are designed to flex (f= unny that) and cracking is not limited to our setup.
There are companies that specialise in stronger flex plates, particularly f= or modified and higher horsepower engines.

Since our engines are being used at a higher horsepower per unit time and t= herefore higher stress (assumption) perhaps our setup could be likened to r= ace applications.
But then our hours of use would be significantly lower (assumption) than an= average vehicle, but perhaps not a race application.
Is the cracking we are seeing consistent with race applications? But they d= ont race automatics, do they?

So my take on this is that perhaps the flexing of the plate in our setup is= to some extent higher than OEM.

Our options seem to be:
1. Replacing the OEM flex plate with a stronger part. Steve B being the lat= est going down that track and in his case also removing the rubber isolatio= n in the process.
2. Connect direct to the eccentric shaft and therefore taking the stress of= f the Flex Plate doing away with the damping mechanism which Tracy did, and= perhaps is still doing. Would be real nice to know.

Like M, I would appreciate hearing what others know or are thinking or doin= g.

Steve Izett












> On 10 Jan 2025, at 2:15=E2=80=AFam, Marc Wiese cardmarc@charter.net <flyrotary@lancaironline.net> wrote:
>
> Has the cause of these cracks been uncovered, and if so, what is the c= urrent thinking on it? An AL racing plate?
> M
> Sent from my iPhone
>
>> On Jan 9, 2025, at 1:31=E2=80=AFAM, Steven W. Boese SBoese@uwyo.edu <flyrotary@lancaironline.net> wrote:
>>
>> =EF=BB=BFSteve,
>>
>> I didn=E2=80=99t see the cracks prior to disassembly and doubt tha= t they could have been seen on the counterweight side very well -if at all-= when assembled.
>>
>> I replaced the Flexplate with a steel flywheel about a year ago.= =C2=A0 Since then, I replaced the four rubber dampers with machined aluminu= m discs giving a solid connection and then dynamically balanced the system.= =C2=A0 This was done because maintaining a dynamic balance wasn=E2=80=99t possible with the dampers.=C2=A0 Only a few hours o= f flight have occurred in this configuration so far and there has been no i= ndication of problems resulting from this change.
>>
>> Steve Boese
>>
>>> On Jan 8, 2025, at 11:03=E2=80=AFPM, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
>>>
>>> =EF=BB=BF=E2=97=86 This message was sent from a non-UWYO addre= ss. Please exercise caution when clicking links or opening attachments from= external sources.
>>>
>>>
>>> Hi Steve
>>>
>>> Is this recent then?
>>>
>>> I=E2=80=99m not able to get to my aircraft at present to check= my flex plate which has probably seen 50 hours of service.
>>>
>>> Was it possible to see these cracks assembled?
>>>
>>> I would appreciate your reflections on Tracys latter choice to= remove the damper, and particularly when using a timber/glass prop such as= an MT.
>>>
>>> It would be great to have an update and current info from Trac= y regarding his no damper hours if anyone can contact him.
>>>
>>> Very helpful, thanks again Steve
>>>
>>> Steve
>>
>> --
>> Homepage:=C2=A0 http://www.flyrotary.com/
>> Archive and UnSub:=C2=A0 =C2=A0ht= tp://mail.lancaironline.net:81/lists/flyrotary/List.html
>
>
>
> --
> Homepage:=C2=A0 http://www.flyrotary.com/
> Archive and UnSub:=C2=A0 =C2=A0http:/= /mail.lancaironline.net:81/lists/flyrotary/List.html



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