X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4472510 for flyrotary@lancaironline.net; Sun, 19 Sep 2010 10:53:38 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=SsAsUFxH7GCXazXoRQ+phCALgYvZXVTLmYsiz8VgUl8= c=1 sm=0 a=Sz4dfeK7adwA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=r1ClD_H3AAAA:8 a=3oc9M9_CAAAA:8 a=Ia-xEzejAAAA:8 a=pGLkceISAAAA:8 a=A9nnTjI4CYraZnGnL4QA:9 a=2-VmaIHF0es5nFI4qVgA:7 a=zzrprKxZIn9CG7_M8EY4i8okNskA:4 a=wPNLvfGTeEIA:10 a=U8Ie8EnqySEA:10 a=EzXvWhQp4_cA:10 a=MSl-tDqOz04A:10 a=CjxXgO3LAAAA:8 a=E93lBu2AAAAA:8 a=WwiWsXONU20axb8O7AIA:9 a=ZIAOjrY2R2ra0vevT0AA:7 a=qdh8Q-p4-JprOA4wLwyBgptRbXcA:4 a=rC2wZJ5BpNYA:10 a=hO30gm18fF0A:10 a=MpuOTR30KwMA:10 a=x6VBWS02HY8A:10 a=d1n8sfsg-lQA:10 a=NWVoK91CQyQA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:52252] helo=EdPC) by cdptpa-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 94/FE-06158-BC3269C4; Sun, 19 Sep 2010 14:53:00 +0000 Message-ID: <299EFB3F21804EDBA530BBFB764C0863@EdPC> From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Check PSRU Oil Drain-back hose was Re: Watch that psru oil seal Date: Sun, 19 Sep 2010 10:52:03 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0044_01CB57E8.B161B1B0" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_0044_01CB57E8.B161B1B0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Check that the drain-back hose is not restricted/crimped in some manner = as well, Mark.=20 While blow-by pressure in the crankcase could pressurize the oil-drain = back a few psi and possible cause the seal blow out - a = blocked/restricted drain-back hose will almost certainly cause the seal = to blow out very quickly. So I would also carefully check the = drain-back hose/line for possible blockage or restrictions. While the oil pressure is nominally down to almost zero at drain-back, = IF the drain back line is restricted/blocked for some reason, then the = oil pressure there can very quickly build up close to 80 psi in the PSRU = drain back area. =20 The reason is that while the oil is flowing normally through the PSRU = then the oil pressure is dropped across the various restrictions it = meets it meets in the gearbox so that is zero by time its ready to drain = back. But, once the oil stops flowing out (due to say a blocked hose), = then there is little/ no pressure drop in the PSRU as the flow = decreases/stops - this means that the pressure of the oil at the drain = point will eventually climb to/near the input oil pressure level of 80 = psi. An electrical analogy is that if you have a resistor and apply voltage = to one end and ground (sink) the other end, you will measure the applied = voltage (oil pressure) on the one end and zero voltage on the grounded = (sink) end. However, if you remove the ground (sink), you will find the = voltage(oil pressure) will measure the same on both sides of the = resistor - no current/oil flow =3D> no voltage/pressure drop. =20 I personally find it hard to believe that give the oil pressure could = rise to 80 psi at the drain back point that blow-by pressure in the pan = would prevent drain back. But, it could offer enough back pressure to = cause the oil in the drain back area of the PSRU to climb to a pressure = level matching the blow-by pressure - I would think at most 2-3 psi. = But, That may be more than enough - if the seal is not designed to = handle it. Ed From: Mark Steitle=20 Sent: Sunday, September 19, 2010 9:18 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Check PSRU Oil Drain-back hose was Re: Watch = that psru oil seal Ed,=20 You and Lynn may have hit on something regarding the crankcase vent line = being too small. It may have been marginally acceptable with the side = port engine, but way undersized for the fire-breathing p-port. First = time I ran it real hard, out came the seal. I am using the stock vent = line, but will go ahead and up-size it while I'm fixing the psru seal. =20 Mark On Sun, Sep 19, 2010 at 8:10 AM, Ed Anderson = wrote: Mark, here's another thing to check for - the oil drain back hose from = the PSRU The PSRU typically has its oil drain-back to the oil pan which can be = "pressurized" by blow-by of the rotors. This back pressure could = impede the flow back of oil from the PSRU because by the time the oil in = the PSRU is ready to drain back it has dropped the oil pressure from its = 80 psi input to practically zero. So it basically gravity feed back to = the oil pan. I guess the oil pan pressure could get to the point of = serioulsy impeding the oil blow - but I would think that much crank case = pressure would have given other indications - such as blowing your dip = stick out {:>) Now if the PSRU oil drain-back became plugged/restricted/crimped for = some reason then the pressure on the seal might eventually reach near = the 80 psi input mark and that would put considerably force on the seal. = So (as I know you already planned) check out the drain back hose. But, in any case mechanically restraining the seal sounds like a smart = ideal in any case Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 http://www.andersonee.com http://www.eicommander.com From: Ben Schneider=20 Sent: Sunday, September 19, 2010 8:39 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Watch that psru oil seal Lynn,=20 Am I reading you right in saying that it it was crankcase = pressure, not oil pressure. And to relieve said pressure, one needs a = larger relief tube than the factory one on the oil fill. (call it = perhaps 3/16" without going to the hanger and measuring) Ben --- On Sun, 9/19/10, Lehanover@aol.com = wrote: From: Lehanover@aol.com Subject: [FlyRotary] Re: Watch that psru oil seal To: "Rotary motors in aircraft" Date: Sunday, September 19, 2010, 7:14 AM In a message dated 9/19/2010 5:41:35 A.M. Eastern Standard = Time, msteitle@gmail.com writes: Kelly, =20 My custom adapter plate was built on a Bridgeport mill. The = hole spacing (and sizes) were obtained from a drawing for the actual = RD-2C plate. Could it be a thou or two oversize? I guess that's = possible, but I don't think so. The machinist that did the work is very = meticulous. However, before reassembly, I'll definitely check it to be = sure. The bottom line is that there is 90-100 psi trying to push it out = of place. So, I feel that a mechanical fastener is the only real way to = guarantee that it stays put 100% of the time. =20 Mark Anything not positively retained in aircraft, will eventually = fall off. Garlock style lip seals will just barely hold back oil splash = with little to no pressure. You see Garlocks pressed into cavities that = are cast or formed with retaining lips at the end. Not into smooth = bores. More than a few pounds against a lip seal over heats the seal and = fails the lip allowing a leak. Note the oil drainback paths in the = rotary, so seals see no pressure even beside a main bearing other than = from crank case gasses..=20 I had a weaver Brothers three section dry sump pump that had = the pressure section in the blind end of a casting so no high = pressurized oil was exposed to a seal of any kind. The drive shaft = extended from the scavenge pump end, so any pressure pulses would of = minimal size against the Garlock seal pressed into a smooth bore in the = end plate. Each session the seal would be found dancing along the shaft = with oil dripping off of everything. A competitor told me to retain the = seal with a plate of some kind. Once that very long weekend was over I = did that with a plate and three little screws. I replaced the single lip = seal with 2 half width lip seals and the plate and never had another = problem. I also cut a tiny groove from the suction side of the pump to = the center of the shaft cavity. Oil drain-back to a lower pressure area. = Lip seals are the most freedom loving seals of all. If = pressurized they turn their lips inside out and leak on you. If you persist, they will escape the bore and dump your oil = out on the ground. They have been that way since the first day. Thought = should be expended on the release of crank case gasses. The street = engine has a tiny tube sticking out of the oil filler neck. This is way = too small for operation above about 3500 RPM.=20 Lynn E. Hanover=20 ------=_NextPart_000_0044_01CB57E8.B161B1B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Check that the drain-back hose is not = restricted/crimped=20 in some manner as well, Mark. 
 
While blow-by pressure in the crankcase could = pressurize=20 the oil-drain back a few psi and possible cause the seal blow out - a=20 blocked/restricted drain-back hose will almost certainly cause the seal = to blow=20 out very quickly.  So I would also carefully check the drain-back = hose/line=20 for possible blockage or restrictions.
 
While the oil pressure is nominally down to = almost zero at=20 drain-back, IF the drain back line is = restricted/blocked for=20 some reason, then the oil pressure there can very quickly build up = close to=20 80 psi in the PSRU drain back area. 
 
The reason is that while the oil  is = flowing normally=20 through the PSRU then the oil pressure is dropped across the various=20 restrictions it meets it meets in the gearbox so that is zero by time = its ready=20 to drain back.  But, once the oil stops flowing out (due to say a = blocked=20 hose), then there is little/ no pressure drop in the PSRU as the flow=20 decreases/stops - this means that the pressure of the oil at the drain = point=20 will eventually climb to/near  the input oil pressure level of 80=20 psi.
 
An electrical analogy is that if you have a = resistor and=20 apply voltage to one end and ground (sink) the other end, you will = measure the=20 applied voltage (oil pressure) on the one end and zero voltage on the = grounded=20 (sink) end.  However, if you remove the ground (sink), you will = find the=20 voltage(oil pressure) will measure the same on both sides of the = resistor - no=20 current/oil flow =3D> no voltage/pressure drop. 
 
I personally find it hard to believe that give = the oil=20 pressure could rise to 80 psi at the drain back point that blow-by = pressure in=20 the pan would prevent drain back.  But, it could offer enough back = pressure=20 to cause the oil in the drain back area of the PSRU to climb to a = pressure level=20 matching the blow-by pressure - I would think at most 2-3 psi.  = But, That=20 may be more than enough - if the seal is not designed to handle = it.
 
Ed

From: Mark Steitle
Sent: Sunday, September 19, 2010 9:18 AM
Subject: [FlyRotary] Re: Check PSRU Oil Drain-back hose was = Re:=20 Watch that psru oil seal

Ed,=20

You and Lynn may have hit on something regarding the crankcase vent = line=20 being too small.  It may have been marginally acceptable with the = side port=20 engine, but way undersized for the fire-breathing p-port.  First = time I ran=20 it real hard, out came the seal.  I am using the stock vent line, = but will=20 go ahead and up-size it while I'm fixing the psru seal.  

Mark

On Sun, Sep 19, 2010 at 8:10 AM, Ed Anderson = <eanderson@carolina.rr.com&g= t;=20 wrote:
Mark, here's another thing to check for - the = oil drain=20 back hose from the PSRU
 
The PSRU typically has its oil drain-back to = the oil pan=20 which can be "pressurized" by blow-by of the rotors.  This back=20 pressure could  impede the flow back of oil from the PSRU = because by=20 the time the oil in the PSRU is ready to drain back it has dropped the = oil=20 pressure from its 80 psi input to practically zero.  So it = basically=20 gravity feed back to the oil pan.   I guess the oil pan = pressure could get to the point of serioulsy impeding the oil blow - = but I=20 would think that much crank case pressure would have given other = indications -=20 such as blowing your dip stick out {:>)
 
Now if the PSRU oil drain-back became=20 plugged/restricted/crimped  for some reason then the pressure on = the seal=20 might eventually reach near the 80 psi input mark and that would = put=20 considerably force on the seal.  So (as I know you already = planned) check=20 out the drain back hose.
 
But, in any case mechanically restraining = the seal=20 sounds like a smart ideal in any case
 
Ed
Edward L. Anderson
Anderson = Electronic=20 Enterprises LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

From: Ben Schneider =
Sent: Sunday, September 19, 2010 8:39 AM
To: Rotary = motors in=20 aircraft
Subject: [FlyRotary] Re: Watch that psru oil=20 seal

Lynn,=20

  Am I reading you right in saying that it it was = crankcase pressure, not oil pressure. And to relieve said = pressure, one=20 needs a larger relief tube than the factory one on the oil fill. = (call=20 it perhaps 3/16" without going to the hanger and = measuring)

Ben

--- On Sun, 9/19/10, Lehanover@aol.com=20 <Lehanover@aol.com> wrote:

From:=20 Lehanover@aol.com=20 <Lehanover@aol.com>
Subject: = [FlyRotary] Re:=20 Watch that psru oil seal
To: "Rotary motors in aircraft" = <flyrotary@lancaironline.net>
Date: = Sunday,=20 September 19, 2010, 7:14 AM

In a message dated 9/19/2010 5:41:35 A.M. Eastern = Standard Time,=20 msteitle@gmail.com writes:
Kelly, =20

My custom adapter plate was built on a Bridgeport mill. =  The hole spacing (and sizes) were obtained from a = drawing for=20 the actual RD-2C plate.  Could it be a thou or two = oversize?=20  I guess that's possible, but I don't think so. =  The=20 machinist that did the work is very meticulous. =  However,=20 before reassembly, I'll definitely check it to be sure. =  The=20 bottom line is that there is 90-100 psi trying to push it = out of=20 place.  So, I feel that a mechanical fastener is the = only real=20 way to guarantee that it stays put 100% of the time. =  

Mark
Anything not positively retained in aircraft, will = eventually=20 fall off. Garlock style lip seals will just barely hold back = oil=20 splash with little to no pressure. You see Garlocks  = pressed into=20 cavities that are cast or formed with retaining lips at the = end. Not=20 into smooth bores. More than a few pounds against a lip seal = over=20 heats the seal and fails the lip allowing a leak. Note the oil = drainback paths in the rotary, so seals see no pressure even = beside a=20 main bearing other than from crank case gasses..
 
I had a weaver Brothers three section dry sump pump that = had the=20 pressure section in the blind end of a casting so no high = pressurized oil was exposed to a seal of any kind. The drive = shaft=20 extended from the scavenge pump end, so any pressure pulses = would of=20 minimal size against the Garlock seal pressed into a = smooth bore=20 in the end plate. Each session the seal would be found dancing = along=20 the shaft with oil dripping off of everything. A competitor = told me to=20 retain the seal with a plate of some kind. Once that very long = weekend=20 was over I did that with a plate and three little screws. I = replaced=20 the single lip seal with 2 half width lip seals and the = plate and=20 never had another problem. I also cut a tiny groove from the = suction=20 side of the pump to the center of the shaft cavity. Oil = drain-back to=20 a lower pressure area. 
 
Lip seals are the most freedom loving seals of all. If=20 pressurized they turn their lips inside out and leak on = you.
 
If you persist, they will escape the bore and dump your = oil out=20 on the ground. They have been that way since the first day. = Thought=20 should be expended on the release of crank case gasses. The = street=20 engine has a tiny tube sticking out of the oil filler neck. = This is=20 way too small for operation above about 3500 RPM.
 
Lynn E.=20 = Hanover

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