X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 25 Jun 2011 12:35:57 -0400 Message-ID: X-Original-Return-Path: Received: from nm19-vm0.bullet.mail.ac4.yahoo.com ([98.139.53.212] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with SMTP id 5031787 for lml@lancaironline.net; Sat, 25 Jun 2011 01:18:42 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.53.212; envelope-from=chris_zavatson@yahoo.com Received: from [98.139.52.191] by nm19.bullet.mail.ac4.yahoo.com with NNFMP; 25 Jun 2011 05:18:07 -0000 Received: from [98.139.52.152] by tm4.bullet.mail.ac4.yahoo.com with NNFMP; 25 Jun 2011 05:18:07 -0000 Received: from [127.0.0.1] by omp1035.mail.ac4.yahoo.com with NNFMP; 25 Jun 2011 05:18:06 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 996087.69267.bm@omp1035.mail.ac4.yahoo.com Received: (qmail 22861 invoked by uid 60001); 25 Jun 2011 05:18:05 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=V12KFWgIIWa7kJVZDPspoOt8AMOMXGHIkdodCWTef0oB6vVsLQVhCaeh88IY5MDgP3eNA43P9HRFgulJcZwn7dHXMlgS+oesuQekKG3+XxZJ5KpPYtaCNGcgpH8SZYQgzGPq57s/dS/27ctD965Oh4JR83zENdxUiW2Y9XA60VQ=; X-YMail-OSG: 9HlN4mAVM1lPQbTpXsR_tHJt5TAqJVBWSZulgHleni.wu7Q gANOd3s3WxKOIvD_rcaaMdvrvKKvNiQHznf9W0UZOU4mtl1DXXNaX3.fuAp0 .EOablcxO6OhdRjZHIgqOEdiqH0CJqYcdOao0p2KoNKOF9uJICNqqFPIAoUr Zm2BN4m9s5Gt0VN2WgoVeihmDz5ro6CRQsGacu.OI7ChXAR2s3uUiiPJUw2E 8BtGluuzPKSNHT0k.N3w0cyXjvuQKDcmtEnyelayvMVh0L7a7LBjypgxCq8W xbk1K.XyhSFmC6DYnkx9RRO6s2iqanBzon8_hCi2nw21kl4QH_YnEipC7F6f RBYeV0KRToTStQp1GQP9jsOuCtieLQ1zjIh.ngrhRDVXTmLK6.sTgP305L9j xtqhNoKUTrEi4fsGwZ2D6qzrJDa1_Zyo8rKfkV.yHc21ak0S_K2BEuC6pM5e V4ugILvai63e7QmePJbjSIPemitQIP1RuQpc9gp2fioahtF._dA-- Received: from [99.171.127.4] by web36905.mail.mud.yahoo.com via HTTP; Fri, 24 Jun 2011 22:18:05 PDT X-Mailer: YahooMailWebService/0.8.112.307740 References: X-Original-Message-ID: <1308979085.16811.YahooMailNeo@web36905.mail.mud.yahoo.com> X-Original-Date: Fri, 24 Jun 2011 22:18:05 -0700 (PDT) From: Chris Zavatson Reply-To: Chris Zavatson Subject: Re: [LML] Re: LNC2 Gear Hydraulics X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-462922783-1308979085=:16811" --0-462922783-1308979085=:16811 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Curiosity got the best of me.=A0 Here are=A0the=A0peak vibration values rec= orded today at the hydraulic pump measured on the axis=A0of the spool valve= .=0AStart up:=A0 +/- 1.3 g=0ATake off:=A0 +/- 0.3 g=0ACruise:=A0 +/- 0.1 g= =0ADescent:=A0 +/- 0.1 g=0ALanding:=A0 +/- 0.6 g=0AIt would appear the O-ri= ng has more design margin than just about any other component on the plane.= =0A=A0=0AChris Zavatson=0AN91CZ=0A360std=0Awww.N91CZ.com=0A=A0=0A=0AFrom: W= olfgang =0ATo: lml@lancaironline.net=0ASent: Friday, Ap= ril 15, 2011 10:11 AM=0ASubject: [LML] Re: LNC2 Gear Hydraulics=0A=0AFrom a= design point of view, I still have a big concern about relying on the fric= tion from an O-ring to keep the landing gear functioning properly. Vibratio= n levels can exceed 70 G's. I would be much happier with a spring loaded ba= ll detent or something similar.=0A=A0=0AThat's why I came up with the gear = fix=A0module.=0A=A0=0AWolfgang=0A=A0=0A----- Original Message ----- =0A>Fro= m: Chris Zavatson =0A>To: lml@lancaironline.net =0A>Sent: Wednesday, April = 13, 2011 8:25 AM=0A>Subject: Re: [LML] Re: LNC2 Gear Hydraulics=0A>=0A>=0A>= A symmetric back-pressure circuit and spool will eliminate the possibility = of installing the spool backwards as happened with pumps manufactured in ab= out the '96 through '98 time frame.=A0 The spool must still remain in place= after the pump shuts down to prevent both high and low circuits from locki= ng up simultaneously.=0A>Using o-ring=A0013-70 requires 30 g's to move the = spool.=0A>Using o-ring=A0013-90 requires 70 g's to move the spool.=0A>This = includes the return force generated by the poppet springs (410462).=A0 =0A>= The difference between the two o-rings is durometer.=A0 I have been using t= he softer one without any problems.=A0 The stiffer o-ring (intended for pum= ps with back pressure circuits) should leave no doubt.=A0 The first thing t= o do with a pump that has a history of locking up both sides is to measure = the return force for the spool and make sure it has an o-ring installed.=0A= >=0A>Chris Zavatson=0A>N91CZ=0A>360std=0A>www.N91CZ.net=0A>=0A>=0A>From: Wo= lfgang =0A>To: lml@lancaironline.net=0A>Sent: Mon, Apri= l 11, 2011 4:56:57 AM=0A>Subject: [LML] Re: LNC2 Gear Hydraulics=0A>=0A>Whe= n I first got into this problem with the hydraulic pumps last year, I had a= few conversations with the product manager of the Oildyne 108 pump. There = have been many changes in it's production life and one of them was to make = the spool symmetrical and have the relief circuit the same both ways.=0A>= =A0=0A>Wolfgang=0A>Wolfgang,=0A>Yes, I have considered this. =A0The spool w= ith O-ring is a very tight fight. =A0While I have not tried to measure the = force to move it, I would estimate something over 50 g's to move it (I'll m= easure this the next time I have a pump opened up) =A0Could it be that a pu= mp somehow ended up mounted such that it was subjected to some resonant fre= quency? =A0Seems like a remote possibilty given all the variables and the m= ass of the pump. =A0 =A0How about wear and tear?=A0=A0Perhaps sitting dry a= nd idle for ten years would do it. =A0A missing O-ring or a spool that does= n't utilize an O-ring would allow the spool to move very easily. =A0Parker = does make spools that don't even have O-rings. =A0Did these end up getting = installed by chance?=0A>=0A>=0A>Based on reports from the LML, the behavior= seems to be rather binary. =A0On the one hand we have planes with over 100= 0 hours and more than ten years of service that have never once had the spo= ol move off the poppet. =A0On the other hand, we have planes with circuits = that lock up right out of the box (put into service).=0A>This leads me to b= elieve there is a difference in configuration. =A0The easiest way to verify= this is to simply open up a pump that is known to lock up hi and low circu= its simultaneously.=0A>=0A>=0A>While I have opened up several pumps (primar= ily to flip around spool valves), I have not yet worked on one that had thi= s lock up issue. =A0I am optimistic the difference will be quite obvious up= on inspection. =A0=0A>=0A>=0A>Chris Zavatson=0A>N91CZ=0A>360std=0A>www.N91C= Z.net=0A>=0A>=0A>=0A>Sent from my iPad=0A>On Apr 7, 2011, at 11:53 AM, "Wol= fgang" wrote:=0A>Chris, have you considered what effec= t airframe vibration has on the position of the spool in the pump and the p= roblem in general ?=0A>>=A0=0A>>Wolfgang=0A>>From: Chris =0A>>Sender: =0A>>Subject: Re: [LML] Re: = LNC2 Gear Hydraulics =0A>>Date: Wed, 06 Apr 2011 07:38:35 -0400 =0A>>To: lm= l@lancaironline.net =0A>>I would like to extend the offer to the whole gr= oup. =A0I think the entire community would benefit from understanding why s= ome pumps are allowing the system to lock up. =A0If anyone has a pump that = exhibits this behavior and could part with it for a week, I am willing to c= heck it out on the test stand and examine the internal configuration.=0A>>C= hris Zavatson=0A>>N91CZ=0A>>360std=0A>>www.N91CZ.net --0-462922783-1308979085=:16811 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Curiosity got the best of me.  Here are th= e peak vibration values recorded today at the hydraulic pump measured on the axi= s of the spool valve.
Start up:  +/- = 1.3 g
Take off:  +/- = 0.3 g
Cruise:  +/- 0.= 1 g
Descent:  +/- 0= .1 g
Landing:  +/- 0= .6 g
It would appear the = O-ring has more design margin than just about any other component on the plane.
 
Chris Zavatson
N91CZ
360std
 

From: Wol= fgang <Wolfgang@MiCom.net>
To= : lml@lancaironline.net
= Sent: Friday, April 15, 2011 10:11 AM
Subject: [LML] Re: LNC2 Gear Hydraulics
From a design point of view, I still have = a big concern about relying on the friction from an O-ring to keep the land= ing gear functioning properly. Vibration levels can exceed 70 G's. I would = be much happier with a spring loaded ball detent or something similar.
 
That's why I came up= with the gear fix module.
 
Wolfgang
 
----- Original Message -----
Sent: Wednesda= y, April 13, 2011 8:25 AM
Subject: Re: [LML] Re: LNC2 Gear Hydraulics

A symmetric back-pressure circuit and spool will eliminate the possibi= lity of installing the spool backwards as happened with pumps manufactured = in about the '96 through '98 time frame.  The spool must still remain = in place after the pump shuts down to prevent both high and low circuits fr= om locking up simultaneously.
Using o-ring 013-70 requires 30 g's to move the spool.
Using o-ring 013-90 requires 70 g's to move the spool.
This includes the return force g= enerated by the poppet springs (410462). 
The difference between the two o-rings is durometer.  I have been using the softer one with= out any problems.  The stiffer o-ring (intended for pumps with back pr= essure circuits) should leave no doubt.  The first thing to do with a = pump that has a history of locking up both sides is to measure the return f= orce for the spool and make sure it has an o-ring installed.
 
Chris Zavatson
N91CZ
360std
<= BR>
From: Wol= fgang <Wolfgang@MiCom.net>
To= : lml@lancaironline.net
= Sent: Mon, April 11, 2011 4:56:57 AM
Subject: [LML] Re: LNC2 Gear Hydraulics
When I first got into this problem with th= e hydraulic pumps last year, I had a few conversations with the product man= ager of the Oildyne 108 pu= mp. There have been many changes in it's production life and one of them wa= s to make the spool symmetrical and have the relief circuit the same both w= ays.
 
Wolfgang
Wolfgang,
Yes, I have considered this.  The spool with O-ring is a very tig= ht fight.  While I have not tried to measure the force to move it, I w= ould estimate something over 50 g= 's to move it (I'll measure this the next time I have a pump opened = up)  Could it be that a pump somehow ended up mounted such that it was= subjected to some resonant frequency?  Seems like a remote possibilty given all the variables= and the mass of the pump.    How about wear and tear?  Perhaps sitting dry and idle for ten years would do it= .  A missing O-ring or a spool that doesn't utilize an O-ring would al= low the spool to move very easily.  Parker does make spools that don't= even have O-rings.  Did these end up getting installed by chance?

Based on reports from the = LML, the behavior seems to be rather binary.  On the one hand we have = planes with over 1000 hours and more than ten years of service that have ne= ver once had the spool move off the poppet.  On the other hand, we hav= e planes with circuits that lock up right out of the box (put into service)= .
This leads me to believe t= here is a difference in configuration.  The easiest way to verify this= is to simply open up a pump that is known to lock up hi and low circuits s= imultaneously.

While I have opened up several pumps (primarily to flip around spool v= alves), I have not yet worked on one that had this lock up issue.  I a= m optimistic the difference will be quite obvious upon inspection.  

Chris Zavatson
N91CZ
360std


Sent from my iPad=
On Apr 7, 2011, at 11:53 AM, "Wolfgang" <Wolfgang@MiCom.net> wrote:
Chris, have you considered what effect air= frame vibration has on the position of the spool in the pump and the proble= m in general ?
 
Wolfgang
=
From: Chris <chris_zavatson@yahoo.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: LNC2 Gear Hydraulics
Date: Wed, 06 Apr 2011 07:38:35 -0400
To: lml@lancaironline.net
I would like to extend the offer to the whole group.  I think the= entire community would benefit from understanding why some pumps are allow= ing the system to lock up.  If anyone has a pump that exhibits this be= havior and could part with it for a week, I am willing to check it out on t= he test stand and examine the internal configuration.
Chris Zavatson
N91CZ
360std
<= A href=3D"http://www.n91cz.net/" rel=3Dnofollow target=3D_blank>www.N91CZ.net
=
=
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