X-Junk-Score: 0 [] X-KAS-Score: 0 [] From: "Marc Wiese cardmarc@charter.net" Received: from [47.43.20.30] (HELO impout006.msg.chrl.nc.charter.net) by logan.com (CommuniGate Pro SMTP 6.4.0) with ESMTPS id 2657631 for flyrotary@lancaironline.net; Wed, 29 Nov 2023 10:24:37 -0500 Received-SPF: pass receiver=logan.com; client-ip=47.43.20.30; envelope-from=cardmarc@charter.net Received: from HomeDesktop ([66.52.82.176]) by cmsmtp with ESMTPA id 8MQDroojm46f38MQErus6M; Wed, 29 Nov 2023 15:24:19 +0000 Authentication-Results: charter.net; auth=pass (LOGIN) smtp.auth=cardmarc@charter.net X-Authority-Analysis: v=2.4 cv=RNOgoqu+ c=1 sm=1 tr=0 ts=656757a3 a=KghLal0A3PxCFfZJiIvcyg==:117 a=KghLal0A3PxCFfZJiIvcyg==:17 a=DAwyPP_o2Byb1YXLmDAA:9 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=ayC55rCoAAAA:8 a=yMhMjlubAAAA:8 a=_6GpL_ENAAAA:8 a=Dye9-ie7GiNJB0HW1c0A:9 a=QEXdDO2ut3YA:10 a=SSmOFEACAAAA:8 a=4d2D4LtiAAAA:8 a=_4y8pkkkeIEEL4pJv2kA:9 a=ikmMrm97EPQdEhYa:21 a=gKO2Hq4RSVkA:10 a=UiCQ7L4-1S4A:10 a=hTZeC7Yk6K0A:10 a=frz4AuCg-hUA:10 a=lqcHg5cX4UMA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=hJnrvW8ITIrk0Oi8sSDQ:22 To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Re: RD-C input shaft failure Date: Wed, 29 Nov 2023 09:24:17 -0600 Message-ID: <012601da22d8$1f8cea60$5ea6bf20$@charter.net> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0127_01DA22A5.D4F3B2E0" X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQJG7OTz8CoirQc7DBQXy2lg9O9E6q+31eBw Content-Language: en-us X-CMAE-Envelope: MS4xfDsZFsOsMOP/g5zQx29IcHR4gfWF+jWZlbucH23PXSXlR/Iuo9V6QQZPejmUb1hTOSOAJbxk+fZGZW3p/LFcZlozYVo926Ai27kcKMwsMZuY6QjRpiJL EOh8EYnEIaJaROkE34C0YjUpBhKn/008/aRig+RWHKyOU08fVfM9xtdkBrT/qfS4EH4rlinjxzbfcA== This is a multipart message in MIME format. ------=_NextPart_000_0127_01DA22A5.D4F3B2E0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Did Tracy ever publish a fix for this failure mode, and did ALL his = models have this weakness? IOW, was there ever a -D model or when did = the C begin the mods to overcome this weakness? M =20 On 28 Nov 2023, at 12:07=E2=80=AFpm, David Leonard wdleonard@gmail.com = > wrote: =20 Hi Dennis,=20 This happened to me 3 times, Once with the older style weld, and then = twice with the pin. After the pin sheared for the second time I sent it = back to Tracy and he placed a second pin 90 deg to the first one. That = fix has held up for a couple hundred hours including racing at Reno = (appx 300h.p.). =20 Of note, 2 of the failures occurred during long gradual descents at low = power. The other occurred after a backfire during start-up. I have a = suspicion that low power descents cause the prop and engine to = alternately overrun each other causing a rapid hammering back and forth. = This problem is made worse by the somewhat lax gear leash that Tracy = designed into the PSRU. I believe that was a good choice for normal = operation but may make things worse during periods when the plane is = pushing the prop yet enough power is being produced to cause the torque = to alternate directions. =20 So in addition to the 2 pins, I now make sure that I keep adequate power = applied throughout descents so that the torque remains positive. In = steep descents idle power will probably allow the torque to remain = negative which is also OK. =20 Hope you are doing well, glad to hear that you are still flying. A = machine shop should be able to place a new pin and machine a hole for a = second pin. =20 Cheers. David Leonard Turbo Rotary RV-6, N4VY =20 On Mon, Nov 27, 2023 at 7:09=E2=80=AFPM Dennis Haverlah = clouduster@austin.rr.com = > = wrote: The shaft between the RX-8 engine and the reduction drive unit has a = gear secured to the shaft with a steel pin. (The gear drives the = planetary gear set). The steel pin sheared off allowing the gear to = rotate on the shaft. I understand this has happened to others in the = past. I=E2=80=99ve heard that several fixes were proposed or tried = =E2=80=93 welding the pin to the gear, doing more deforming of the pin = at the gear surface or installing a tighter or larger pin. I have = another new shaft/gear assembly I plan to install after I incorporate = improvements. =20 When the pin sheared the gear only rotated about 3/32 inch on the shaft. = The two pieces of the pin outside the shaft were thrown out of the gear = and apparently were chewed into very small particles by the planetary = gear assembly. =20 =20 Any info. You may have will be highly appreciated! I have about 920 hours on my RX-8 engine in my RV-7A =20 Dennis Haverlah=20 512-921-0636 =20 Sent from Mail for = Windows =20 =20 =20 =20 =20 = =20 Virus-free. = www.avast.com =20 ------=_NextPart_000_0127_01DA22A5.D4F3B2E0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

Did Tracy ever publish a fix = for this failure mode, and did ALL his models have this weakness? IOW, = was there ever a -D model or when did the C begin the mods to overcome = this weakness?

M

 



On 28 Nov 2023, at 12:07=E2=80=AFpm, David Leonard wdleonard@gmail.com <flyrotary@lancaironline.net> = wrote:

 

Hi = Dennis,

This happened to me 3 = times, Once with the older style weld, and then twice with the = pin.  After the pin sheared for the second time I sent it back to = Tracy and he placed a second pin 90 deg to the first one.  That fix = has held up for a couple hundred hours including racing at Reno (appx = 300h.p.).

 

Of note, 2 of the failures = occurred during long gradual descents at low power.  The = other occurred after a backfire during start-up.  I have a = suspicion that low power descents cause the prop and engine to = alternately overrun each other causing a rapid hammering back = and forth.  This problem is made worse by the somewhat lax gear = leash that Tracy designed into the PSRU.  I believe that was a good = choice for normal operation but may make things worse during periods = when the plane is pushing the prop yet enough power is being produced to = cause the torque to alternate directions.

 

So in addition to the 2 pins, I now make sure that I = keep adequate power applied throughout descents so that the torque = remains positive.  In steep descents idle power will probably allow = the torque to remain negative which is also = OK.

 

Hope you are doing well, glad to hear that you are = still flying. A machine shop should be able to place a new pin and = machine a hole for a second pin.

 

Cheers.

David Leonard

Turbo Rotary RV-6,  = N4VY

 

On = Mon, Nov 27, 2023 at 7:09=E2=80=AFPM Dennis Haverlah clouduster@austin.rr.com <flyrotary@lancaironline.net> = wrote:

The shaft = between the RX-8 engine and the reduction drive unit has a gear secured = to the shaft with a steel pin.  (The gear drives the planetary gear = set). The steel pin sheared off allowing the gear to rotate on the  = shaft.   I understand this has happened to others in the = past.   I=E2=80=99ve heard that several fixes were proposed or = tried =E2=80=93 welding the pin to the gear, doing more deforming of =  the pin at the gear surface or installing a tighter or larger = pin.   I have another new shaft/gear assembly I plan to = install  after I incorporate  improvements.  =

When the = pin sheared the gear only rotated about 3/32 inch on the shaft. The two = pieces of the pin outside the shaft were thrown out of the gear and = apparently were chewed into very small particles by the  planetary = gear assembly. 

 

Any info. = You may have will be highly appreciated!

I have = about 920 hours on my RX-8 engine in my RV-7A

 <= /o:p>

Dennis = Haverlah

512-921-0636=

 <= /o:p>

Sent from = Mail for Windows

 <= /o:p>

 <= /o:p>

 

 

 

V= irus-free.www.avast.com

 

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