X-Junk-Score: 0 [] X-KAS-Score: 0 [] From: "Stephen Izett stephen.izett@gmail.com" Received: from mail-oa1-f54.google.com ([209.85.160.54] verified) by logan.com (CommuniGate Pro SMTP 6.4.0) with ESMTPS id 2652955 for flyrotary@lancaironline.net; Tue, 28 Nov 2023 05:10:24 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.160.54; envelope-from=stephen.izett@gmail.com Received: by mail-oa1-f54.google.com with SMTP id 586e51a60fabf-1f5bd86ceb3so3087511fac.2 for ; Tue, 28 Nov 2023 02:10:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701166208; x=1701771008; darn=lancaironline.net; h=message-id:in-reply-to:to:references:date:subject:mime-version:from :from:to:cc:subject:date:message-id:reply-to; bh=cf0VNrhyD9KZ1KjQp8Rls8EmLxjG7DXLZb+hPOhPjE4=; b=QsywL70PU+/jqVkxy5qPebH3/VcknEnTAvtbVjsI7b5lhR3rfrJ/rXclEwwTlykQFH dPkhfZIcvGUlp0C3CN1shm/M+I4m4oeAXgGC5dFolOav5nHbXCBhMCL7dI/f6Y+LVp4T n4BdCWRjv76rgykjra1lfOTPsihuv9dQ7JBG5zF+AqjBk6WHi8U1mDX3aM4I8ZjeZQF+ skS9P2C4S57CLpo8YIuQ9P9MY4E4fS1DStYdG6vynx8/fFZT0gZeFcL0NBLM/DigTJie DmN9Q36HpRZK2VbjVs7R8TSLFTVi3/9LP0xWOD0vnhUmomVY4KJZoS1rMMUUUDoKKOhl tLrw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701166208; x=1701771008; h=message-id:in-reply-to:to:references:date:subject:mime-version:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=cf0VNrhyD9KZ1KjQp8Rls8EmLxjG7DXLZb+hPOhPjE4=; b=fN4Ve8ehkYvlrLMNj6RIBNr+BwET9gHWERQcGwx+948dgvT3Jzs6WsZ9F4pGurxu6S aA7OJm3SaaasAatp5bwhKL1V0TCrb+fLJqovpeCj03qmHWjRDY4Ffl0qNOW0D+YCkipv 2YuqrljFcQYX3CVfSmFYiU1FcvCO82kATMeX3MyDrAjSLsATvNTh/rZw0i+Q2RwzaANK 4X4RYw2eW0aVNkx1sHdx58XQrg44dtBaeg9MYO6/mEEFWoHrr0INQQdLvuk3v2Z0lDwT WLmL2F97hxPIdQTMq8Uq6CXU5GLLXzWKLMHVjmKNc3jDM1khWKF3N4EnUvoykm84Cwiq MQeQ== X-Gm-Message-State: AOJu0YyO3KyNv8X/OEpzwM8V+1KX0H3PGvOFCY9ZLnXJxMD8gcHApECd ED6DcBfnPVRoO/vHWXbE7K4w4X3ipik= X-Google-Smtp-Source: AGHT+IERuOS9esgT4ObhFS31xR9lc7J7DByipb0MWTHqjgJo6/DbysC0vJLbOhb0O/kn+JVNa6RmDQ== X-Received: by 2002:a05:6870:4989:b0:1eb:43a2:cafc with SMTP id ho9-20020a056870498900b001eb43a2cafcmr19510525oab.40.1701166206967; Tue, 28 Nov 2023 02:10:06 -0800 (PST) Return-Path: Received: from smtpclient.apple (220-235-72-153.dyn.iinet.net.au. [220.235.72.153]) by smtp.gmail.com with ESMTPSA id 16-20020aa79150000000b006c2fcb25c15sm8612010pfi.162.2023.11.28.02.10.05 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 Nov 2023 02:10:06 -0800 (PST) Content-Type: multipart/alternative; boundary="Apple-Mail=_8F8B8EA6-D181-40FF-AE3F-67B7F1E247E1" Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.200.91.1.1\)) Subject: Re: [FlyRotary] RD-C input shaft failure Date: Tue, 28 Nov 2023 18:09:52 +0800 References: To: Rotary motors in aircraft In-Reply-To: Message-Id: X-Mailer: Apple Mail (2.3774.200.91.1.1) --Apple-Mail=_8F8B8EA6-D181-40FF-AE3F-67B7F1E247E1 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 I=E2=80=99m wondering how the Sun gear was attached to the shaft in the = orignal Ford transmission? Steve > On 28 Nov 2023, at 6:01=E2=80=AFpm, Stephen Izett = wrote: >=20 > Thanks Dave >=20 > My question about the damper was me wondering if damping the engine = torque pulses reduced the stress on the pin/s >=20 > Steve >=20 >> On 28 Nov 2023, at 5:11=E2=80=AFpm, David Leonard wdleonard@gmail.com = wrote: >>=20 >> There is really no such thing as an AD for these non certified parts. = Yes, my redrive is the RD-1B with the 2.17:1 ratio. The part that = fails here is the connection of the sun gear to the input shaft. The = input shaft fits inside the sun gear and they are fixed in place with = either a weld or a pin or two. The pin is about 3/8 in diameter. =20 >>=20 >> I believe the RC-1C uses the same input shaft and sun gear, but I am = not sure. >>=20 >> This is a different issue from the flywheel. The original design = called for the use of the auto transmission flex plate to transmit the = torque loads from the engine output shaft to the plate with the = dampeners. However, in the car this was only used for starting, and not = to transmit the whole power of the engine. Over time they tend to flex = and crack. There are a couple of different solutions including = replacing the flex plate with a flywheel like I did. >>=20 >> The 3rd failure mode that I came across was my failure to supply a = dedicated oil line from a high pressure area which caused the plain = bearings to seize. However, that was at Reno with high power and high = gyroscopic loads. >>=20 >> Dave Leonard >>=20 >> On Mon, Nov 27, 2023 at 10:33=E2=80=AFPM Stephen Izett = stephen.izett@gmail.com = > = wrote: >>> Hi Guys. >>>=20 >>> Has an AD been issued on the RD1-C PSRU? >>> How many of these failures has there been? >>>=20 >>> Now I=E2=80=99m thinking I understood yours Dave was an earlier = version with a lower ratio but the shaft assembly may be exactly the = same. >>> Do you both have the damper with original shore hardness donuts? I = recall Dave changing to a modified low weight steel or ali flywheel. >>>=20 >>> You have my attention! >>>=20 >>> Steve Izett >>> Genesis 4 Port RD1-C MTV-7C >>>=20 >>>=20 >>>> On 28 Nov 2023, at 12:07=E2=80=AFpm, David Leonard = wdleonard@gmail.com = > = wrote: >>>>=20 >>>> 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.). >>>>=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 >>>>>=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 >>>>> =20 >>>>> Any info. You may have will be highly appreciated! >>>>>=20 >>>>> I have about 920 hours on my RX-8 engine in my RV-7A >>>>>=20 >>>>> =20 >>>>>=20 >>>>> Dennis Haverlah >>>>>=20 >>>>> 512-921-0636 >>>>>=20 >>>>> =20 >>>>>=20 >>>>> Sent from Mail = for Windows >>>>>=20 >>>>> =20 >>>>>=20 >>>>> =20 >>>>>=20 >>>=20 >=20 --Apple-Mail=_8F8B8EA6-D181-40FF-AE3F-67B7F1E247E1 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 I=E2=80=99m = wondering how the Sun gear was attached to the shaft in the orignal Ford = transmission?

Steve


On 28 Nov 2023, at 6:01=E2=80=AFpm, Stephen Izett = <stephen.izett@gmail.com> wrote:

Thanks Dave

My question about the = damper was me wondering if damping the engine torque pulses reduced the = stress on the pin/s

Steve

On 28 Nov 2023, at 5:11=E2=80=AFpm, David Leonard = wdleonard@gmail.com <flyrotary@lancaironline.net> wrote:

There is = really no such thing as an AD for these non certified parts.  Yes, = my redrive is the RD-1B with the 2.17:1 ratio.  The part that fails = here is the connection of the sun gear to the input shaft. The input = shaft fits inside the sun gear and they are fixed in place with either a = weld or a pin or two.  The pin is about 3/8 in = diameter.  

I believe the RC-1C uses = the same input shaft and sun gear, but I am not = sure.

This is a different issue from the = flywheel.  The original design called for the use of the auto = transmission flex plate to transmit the torque loads from the = engine output shaft to the plate with the dampeners.  However, = in the car this was only used for starting, and not to transmit the = whole power of the engine.  Over time they tend to flex and = crack.  There are a couple of different solutions including = replacing the flex plate with a flywheel like I = did.

The 3rd failure mode that I came across = was my failure to supply a dedicated oil line from a high pressure = area which caused the plain bearings to seize.  However, that was = at Reno with high power and high gyroscopic = loads.

Dave Leonard

On Mon, Nov = 27, 2023 at 10:33=E2=80=AFPM Stephen Izett stephen.izett@gmail.com = <flyrotary@lancaironline.net> wrote:
Hi Guys.

Has = an AD been issued on the RD1-C PSRU?
How many of these = failures has there been?

Now I=E2=80=99m = thinking I understood yours Dave was an earlier version with a lower = ratio but the shaft assembly may be exactly the same.
Do you = both have the damper with original shore hardness donuts? I recall Dave = changing to a modified low weight steel or ali = flywheel.

You have my = attention!

Steve Izett
Genesis 4 Port = RD1-C MTV-7C



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

 

Dennis Haverlah

512-921-0636

 

Sent = from Mail for Windows

 

 


=


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