X-Junk-Score: 0 [] X-KAS-Score: 0 [] From: "Charlie England ceengland7@gmail.com" Received: from mail-yw1-f175.google.com ([209.85.128.175] verified) by logan.com (CommuniGate Pro SMTP 6.4.0) with ESMTPS id 2654297 for flyrotary@lancaironline.net; Tue, 28 Nov 2023 10:58:33 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.128.175; envelope-from=ceengland7@gmail.com Received: by mail-yw1-f175.google.com with SMTP id 00721157ae682-5cc66213a34so57259077b3.1 for ; Tue, 28 Nov 2023 07:58:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701187095; x=1701791895; darn=lancaironline.net; h=in-reply-to:from:content-language:references:to:subject:user-agent :mime-version:date:message-id:from:to:cc:subject:date:message-id :reply-to; bh=2b/G8WwGH1BieOQTdCbeALm6IsNzvEQTQtjEBJjeIb8=; b=eqWLwmbJWyusemfNaza4KGr9iwbsozFPBEsIKCBy+PD1B+odbiVtG8YqRWNGuKtCn1 50Ytb+C4D/FVrzv1c+M4nVUrUdGPW1inlMmhbjs402K8XEN6Bh037D4mVwzxszUT/A+Y fQ/ZFK67Is8E5BC7ciZqg+Ooc1cQtzlDyR4OOWR5wp03YEOe/xGtM+IgFm/yEnnQ5A9+ lesGPL7N2rXDovADKTXxwQfIMSxTGkr/AwHyg1aqSVudlRVL3gRXHVu88lGr/2fIXez2 JpQAYN3wgLeCXOfn6V/WWEhqjbsP8PsQ5ArD/ArUEyTrMS7Qr879yl1dA6mF6xLHWjMP hMuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701187095; x=1701791895; h=in-reply-to:from:content-language:references:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=2b/G8WwGH1BieOQTdCbeALm6IsNzvEQTQtjEBJjeIb8=; b=UbGHi/Q0SonE2eq+5CM93TsyqYvVEANMFrJuxpqMTOwaZYIEnL5x0gV1esLFBnpO/d zEeZBsalCGMcImydrhDXofJ3Rl6y5zpHIAy3MUZLH3jf9wyfTSSRCcGEPb5UMSXUiDK0 z8EIcY7fB9DDWiqmqPSf1G7EogYSiIV/57yXHuVllHu2hVrYcFldZgfZViO2+tH/XzBn LQi7apIgwsZ0U+SQsPcN5SNwRm8KyP9YeJzJtatc6sInAFpt0DrZ+Zcei5FmfeSjIb/B L/blMQY5NHmCOnVfcbO9Ez6/cbFFxUhXumx6Vq87iXqiBv7DpiGiOkH87nm8r64nCV13 8m3Q== X-Gm-Message-State: AOJu0Yxli9p5fBbnjhzai9ivt7ylasFhJLdEcNt26pITxhIP1YCsnqfT AbSAlyVQdvSmjw/EdgpAVgolGTcwwoM= X-Google-Smtp-Source: AGHT+IFhpxyEAaOw4WpvK/j7tzjssNa/Q9hc1vimBpRxsk+a7vsTjcInMbQsPbJ6z1dyfepkF1HidA== X-Received: by 2002:a81:9282:0:b0:5a7:afcc:80fe with SMTP id j124-20020a819282000000b005a7afcc80femr9960033ywg.3.1701187095224; Tue, 28 Nov 2023 07:58:15 -0800 (PST) Return-Path: Received: from [192.168.1.52] ([50.86.156.24]) by smtp.googlemail.com with ESMTPSA id c5-20020a0dc105000000b005a4da74b869sm4007362ywd.139.2023.11.28.07.58.14 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Nov 2023 07:58:14 -0800 (PST) Content-Type: multipart/alternative; boundary="------------Wa3p7RTsY8GICFsO7wJDc5pF" Message-ID: <19f73c9b-5cc2-4411-b82e-e51b359f5ef1@gmail.com> Date: Tue, 28 Nov 2023 10:03:06 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [FlyRotary] Re: RD-C input shaft failure To: Rotary motors in aircraft References: Content-Language: en-US In-Reply-To: X-Antivirus: Avast (VPS 231128-2, 11/28/2023), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. --------------Wa3p7RTsY8GICFsO7wJDc5pF Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit In the interest of clarity for newcomers, the flexplate has a history of cracking in automotive use, too. I've got one that never flew that has cracks. Charlie On 11/28/2023 3:11 AM, David Leonard wdleonard@gmail.com 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 PM Stephen Izett stephen.izett@gmail.com > wrote: > > Hi Guys. > > Has an AD been issued on the RD1-C PSRU? > How many of these failures has there been? > > Now I’m 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 > > >> On 28 Nov 2023, at 12:07 pm, David Leonard wdleonard@gmail.com >> 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 PM 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’ve heard that >> several fixes were proposed or tried – 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 >> > -- This email has been checked for viruses by Avast antivirus software. www.avast.com --------------Wa3p7RTsY8GICFsO7wJDc5pF Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit
In the interest of clarity for newcomers, the flexplate has a history of cracking in automotive use, too. I've got one that never flew that has cracks.

Charlie

On 11/28/2023 3:11 AM, David Leonard wdleonard@gmail.com 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 PM 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’m 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


On 28 Nov 2023, at 12:07 pm, 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 PM 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’ve heard that several fixes were proposed or tried – 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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