X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-iw0-f180.google.com ([209.85.214.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4472565 for flyrotary@lancaironline.net; Sun, 19 Sep 2010 12:02:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.180; envelope-from=msteitle@gmail.com Received: by iwn8 with SMTP id 8so4629758iwn.25 for ; Sun, 19 Sep 2010 09:01:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=p7uUYzkwfZ/AJxYVk5D4IX9bzjZqIGZ3gDCSOSd6REE=; b=Xt+tPLNpq7il60MyCG89frzF5wJErkHN2zn0psmKvhLOrpms72AKeyjFd50VZhpOLV ZNA2b9CmX8+3UCDP8LgFsZBDnZIwFiHFK9gEU13vUucOm0jaGOpruUKxbsPu0kpmqtqE yZ6BTwB6evsc6Ebu5u5m6FUPFodR85wMesUJY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=AN6hX9mhD94KJ1LGYUBje4H9c0B+/LZn82YudctdikYhxm/kkfPCeg4lLji4Isc+1Y dNBER5+CIz6MUQMZrsHXhzu9MYTJjbh3lq9poYMXL3gIFwVRMIWtMK20ASkPjrjf0CT5 euh+YUUpE258w6G5Vadj2YjkkLP4vSXXTUe6c= MIME-Version: 1.0 Received: by 10.231.35.77 with SMTP id o13mr8685937ibd.92.1284912108121; Sun, 19 Sep 2010 09:01:48 -0700 (PDT) Received: by 10.231.173.137 with HTTP; Sun, 19 Sep 2010 09:01:48 -0700 (PDT) In-Reply-To: References: Date: Sun, 19 Sep 2010 11:01:48 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Check PSRU Oil Drain-back hose was Re: Watch that psru oil seal From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=000325572daac5b19904909ee986 --000325572daac5b19904909ee986 Content-Type: text/plain; charset=ISO-8859-1 Ed, You can bet that I will be checking all of the above, and then some. Have a safe flight to the alternative engine fly-in. I wish I could be there. Mark On Sun, Sep 19, 2010 at 9:52 AM, Ed Anderson wrote: > Check that the drain-back hose is not restricted/crimped in some manner > as well, Mark. > > 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. > > 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 => no voltage/pressure drop. > > 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 > *Sent:* Sunday, September 19, 2010 9:18 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Check PSRU Oil Drain-back hose was Re: Watch > that psru oil seal > > Ed, > > 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. > > 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 >> *Sent:* Sunday, September 19, 2010 8:39 AM >> *To:* Rotary motors in aircraft >> *Subject:* [FlyRotary] Re: Watch that psru oil seal >> >> Lynn, >> >> 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, >> >> 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. >> >> 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.. >> >> 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. >> >> Lynn E. Hanover >> >> > --000325572daac5b19904909ee986 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Ed,=A0

You can bet that I will be checking all of the ab= ove, and then some. =A0

Have a safe flight to the = alternative engine fly-in. =A0I wish I could be there.

=
Mark=A0

On Sun, Sep 19, 2010 at 9:52 AM, = Ed Anderson <eanderson@carolina.rr.com> wrote:
Check that the drain-back hose is not restricted/= crimped=20 in some manner as well, Mark.=A0
=A0
While blow-by pressure in the crankcase could pre= ssurize=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.=A0 So I would also carefully check the drain-back hose/li= ne=20 for possible blockage or restrictions.
=A0
While the oil pressure is nominally down to almos= t zero at=20 drain-back, IF the drain back line is restricted/blocked f= or=20 some reason, then the oil pressure there=A0can very quickly build up close = to=20 80 psi in the PSRU drain back area.=A0
=A0
The reason is that while the oil=A0 is flowing no= rmally=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 r= eady=20 to drain back.=A0 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 poin= t=20 will eventually climb to/near =A0the input oil pressure level of 80=20 psi.
=A0
An electrical analogy is that if you have a resis= tor 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 groun= ded=20 (sink) end.=A0 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.=A0
=A0
I personally find it hard to believe that give th= e 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.=A0 But, it could offer enough back pressu= re=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.=A0 But, That= =20 may be more than enough - if the seal is not designed to handle it.<= /div>
=A0
Ed

Sent: Sunday, September 19, 2010 9:18 AM
To: Rotary motors in aircraft <= /div>
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 li= ne=20 being too small. =A0It may have been marginally acceptable with the side po= rt=20 engine, but way undersized for the fire-breathing p-port. =A0First time I r= an=20 it real hard, out came the seal. =A0I am using the stock vent line, but wil= l=20 go ahead and up-size it while I'm fixing the psru seal. =A0

Mark

On Sun, Sep 19, 2010 at 8:10 AM, Ed Anderson <eanderson@carolina.rr.com>=20 wrote:
Mark, here's another thing to check for - t= he oil drain=20 back hose from the PSRU
=A0
The PSRU typically has its oil drain-back to th= e oil pan=20 which can be "pressurized" by blow-by of the rotors.=A0 This ba= ck=20 pressure=A0could =A0impede 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 oi= l=20 pressure from its 80 psi input to practically zero.=A0=A0So it basically= =20 gravity feed back to the oil pan.=A0=A0=A0I guess the oil pan=20 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 indicati= ons -=20 such as blowing your dip stick out {:>)
=A0
Now if the PSRU oil drain-back became=20 plugged/restricted/crimped =A0for some reason then the pressure on the se= al=20 might eventually reach near=A0the 80 psi input mark and that would put=20 considerably force on the seal.=A0 So (as I know you already planned) che= ck=20 out the drain back hose.
=A0
But, in any case=A0mechanically restraining the= seal=20 sounds like a smart ideal in any case
=A0
Ed
Edward L. Anderson
Anderson Elect= ronic=20 Enterprises LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

Sent: Sunday, September 19, 2010 8:39 AM
Subject: [FlyRotary] Re: Watch that psru oil=20 seal

Lynn,=20

=A0=A0Am I reading you right in saying that it it was=20 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. (c= all=20 it perhaps 3/16" without going to the hanger and measuring)

Ben

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

From:=20 Lehanover@aol.com=20 <Lehano= ver@aol.com>
Subject: [FlyRotary] Re:=20 Watch that psru oil seal
To: "Rotary motors in aircraft&q= uot; <f= lyrotary@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 T= ime,=20 msteitle@= gmail.com writes:
Kelly,=A0=20

My custom adapter plate was built on a Bridgeport mill.=20 =A0The hole spacing (and sizes) were obtained from a drawing fo= r=20 the actual RD-2C plate. =A0Could it be a thou or two oversize?= =20 =A0I guess that's possible, but I don't think so. =A0Th= e=20 machinist that did the work is very meticulous. =A0However,=20 before reassembly, I'll definitely check it to be sure. =A0= The=20 bottom line is that there is 90-100 psi trying to push it out o= f=20 place. =A0So, I feel that a mechanical fastener is the only rea= l=20 way to guarantee that it stays put 100% of the time. =A0

Mark
Anything not positively retained in aircraft, will eventuall= y=20 fall off. Garlock style lip seals will just barely hold back oil= =20 splash with little to no pressure. You see Garlocks=A0 pressed in= to=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=20 drainback paths in the rotary, so seals see no pressure even besi= de a=20 main bearing other than from crank case gasses..
=A0
I had a weaver Brothers three section dry sump pump that had= the=20 pressure section in=A0the blind end of a casting so no high=20 pressurized oil was exposed to a seal of any kind. The drive shaf= t=20 extended from the scavenge pump end, so any pressure pulses would= of=20 minimal size=A0against the Garlock seal pressed into a smooth bor= e=20 in the end plate. Each session the seal would be found dancing al= ong=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 we= ekend=20 was over I did that with a plate and three little screws. I repla= ced=20 the single lip seal=A0with 2 half width lip seals and the plate a= nd=20 never had another problem. I also cut a tiny groove from the suct= ion=20 side of the pump to the center of the shaft cavity. Oil drain-bac= k to=20 a lower pressure area.=A0
=A0
Lip seals are the most freedom loving seals of all. If=20 pressurized they turn their lips inside out and leak on you.
=A0
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. Thoug= ht=20 should be expended on the release of crank case gasses. The stree= t=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.
=A0
Lynn E.=20 Hanover


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