X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 27 Jun 2011 14:51:24 -0400 Message-ID: X-Original-Return-Path: Received: from nm29.bullet.mail.ac4.yahoo.com ([98.139.52.226] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with SMTP id 5034135 for lml@lancaironline.net; Mon, 27 Jun 2011 13:25:24 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.52.226; envelope-from=chris_zavatson@yahoo.com Received: from [98.139.52.196] by nm29.bullet.mail.ac4.yahoo.com with NNFMP; 27 Jun 2011 17:24:49 -0000 Received: from [98.139.52.136] by tm9.bullet.mail.ac4.yahoo.com with NNFMP; 27 Jun 2011 17:24:49 -0000 Received: from [127.0.0.1] by omp1019.mail.ac4.yahoo.com with NNFMP; 27 Jun 2011 17:24:49 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 818777.85656.bm@omp1019.mail.ac4.yahoo.com Received: (qmail 77432 invoked by uid 60001); 27 Jun 2011 17:24:49 -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=DTFINQwaVo846u5wnGoE896eSw7f3CG0v2JVtiJ7H/qz5XS9pd4bu4I5fr8oLD6He1YTo8m+p4V+T7ix4OOoM53MZG7PMLTOv92x3tx55FUjDnejkWByMClnYOT6Ld3YgJI7BAlCboP7RU1GwfEmNN2oeQ84OHrMS5v/98LZ3+Y=; X-YMail-OSG: HOKYVqkVM1m6ysoHAbPlW3_w8NPZFuPLGTqjSoiW3tVuLIk q2No._JEdA1ti4dP_fOISu1FPuo5E.sh10ENGHv.sdVTMG1dCWagLEeaZW3Z p7MMJtVkbCwgqmnWE2TQafo7362ww9PJkNpXr3E17MZ21SO_3OHTVh8b_XSY yOItSjuUpjJ4jXAnZgDw0EPsbksP5VnjzHY..izbpMEQGtdyiecfik2mJji. pjvvrZQm0_CPsLqXgjw.vcT0aN8lj1uPKpkD8OVrPlX1J60xnY3dCvq0H8aT Ph2GPFr9RSF53zmHipeXIlPVWBJY0EtgEkie8Nq5I9HIfihH09r6oClcQ_dk F9BPZY0mVZQ9CK8inqZw40GeE8_CWpkMeQjuyo3hg3DcVwXuaO0aRvCZK58e 2qofmJ8yXIpGqGG30f5WoVlLsWz0_PBX6ohoRIiZKTwKbcMjAlKLHb178Fjc RiSfWNehmXgyduysuDGQOGK6Ul2KcocMJ20drOLBV2oHL0QUcIA-- Received: from [12.130.164.194] by web36905.mail.mud.yahoo.com via HTTP; Mon, 27 Jun 2011 10:24:48 PDT X-Mailer: YahooMailWebService/0.8.112.307740 References: <003901cc3415$c9b10180$6401a8c0@lobo> <1309187605.9490.YahooMailNeo@web36904.mail.mud.yahoo.com> X-Original-Message-ID: <1309195488.75904.YahooMailNeo@web36905.mail.mud.yahoo.com> X-Original-Date: Mon, 27 Jun 2011 10:24:48 -0700 (PDT) From: Chris Zavatson Reply-To: Chris Zavatson Subject: Fw: [LML] Re: LNC2 Gear Hydraulics X-Original-To: Lancair Mailing List In-Reply-To: <1309187605.9490.YahooMailNeo@web36904.mail.mud.yahoo.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1581527968-1309195488=:75904" --0-1581527968-1309195488=:75904 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Wolfgang,=0AA simple visual examination of the actual parts installed in su= ch an offending pump would be the place to start. This could be as simple a= s an incorrect or missing part.=A0 Without looking we=A0may never know.=0A= =A0=0AChris=A0=0A=A0=0A=0AFrom: Wolfgang =0ATo: Chris Z= avatson =0ASent: Sunday, June 26, 2011 8:29 AM=0A= Subject: Re: [LML] Re: LNC2 Gear Hydraulics=0A=0AInteresting . . . but stil= l leaves the question of how some installations still manage to display the= "fail to=A0function" problem.=0A=A0=0AWolfgang=0A=A0=0A----- Original Mess= age ----- =0A>From: Chris Zavatson =0A>To: lml@lancaironline.net =0A>Sent: = Saturday, June 25, 2011 12:35 PM=0A>Subject: Re: [LML] Re: LNC2 Gear Hydrau= lics=0A>=0A>=0A>Curiosity got the best of me.=A0 Here are=A0the=A0peak vibr= ation values recorded today at the hydraulic pump measured on the axis=A0of= the spool valve.=0A>Start up:=A0 +/- 1.3 g=0A>Take off:=A0 +/- 0.3 g=0A>Cr= uise:=A0 +/- 0.1 g=0A>Descent:=A0 +/- 0.1 g=0A>Landing:=A0 +/- 0.6 g=0A>It = would appear the O-ring has more design margin than just about any other co= mponent on the plane.=0A>=A0=0A>Chris Zavatson=0A>N91CZ=0A>360std=0A>www.N9= 1CZ.com=0A>=A0=0A>=0A>=0A>From: Wolfgang =0A>To: lml@la= ncaironline.net=0A>Sent: Friday, April 15, 2011 10:11 AM=0A>Subject: [LML] = Re: LNC2 Gear Hydraulics=0A>=0A>From a design point of view, I still have a= big concern about relying on the friction from an O-ring to keep the landi= ng gear functioning properly. Vibration levels can exceed 70 G's. I would b= e much happier with a spring loaded ball detent or something similar.=0A>= =A0=0A>That's why I came up with the gear fix=A0module.=0A>=A0=0A>Wolfgang= =0A>=A0=0A>----- Original Message ----- =0A>>From: Chris Zavatson =0A>>To: = lml@lancaironline.net =0A>>Sent: Wednesday, April 13, 2011 8:25 AM=0A>>Subj= ect: Re: [LML] Re: LNC2 Gear Hydraulics=0A>>=0A>>=0A>>A symmetric back-pres= sure circuit and spool will eliminate the possibility of installing the spo= ol backwards as happened with pumps manufactured in about 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 locking up simultaneously.= =0A>>Using o-ring=A0013-70 requires 30 g's to move the spool.=0A>>Using o-r= ing=A0013-90 requires 70 g's to move the spool.=0A>>This includes the retur= n force generated by the poppet springs (410462).=A0 =0A>>The difference be= tween the two o-rings is durometer.=A0 I have been using the softer one wit= hout any problems.=A0 The stiffer o-ring (intended for pumps with back pres= sure circuits) should leave no doubt.=A0 The first thing to 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 Zava= tson=0A>>N91CZ=0A>>360std=0A>>www.N91CZ.net=0A>>=0A>>=0A>>From: Wolfgang =0A>>To: lml@lancaironline.net=0A>>Sent: Mon, April 11, 2= 011 4:56:57 AM=0A>>Subject: [LML] Re: LNC2 Gear Hydraulics=0A>>=0A>>When 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 behav= ior seems to be rather binary. =A0On the one hand we have planes with over = 1000 hours and more than ten years of service that have never once had the = spool move off the poppet. =A0On the other hand, we have planes with circui= ts that lock up right out of the box (put into service).=0A>>This leads me = to believe there is a difference in configuration. =A0The easiest way to ve= rify this is to simply open up a pump that is known to lock up hi and low c= ircuits simultaneously.=0A>>=0A>>=0A>>While I have opened up several pumps = (primarily to flip around spool valves), I have not yet worked on one that = had this lock up issue. =A0I am optimistic the difference will be quite obv= ious upon inspection. =A0=0A>>=0A>>=0A>>Chris Zavatson=0A>>N91CZ=0A>>360std= =0A>>www.N91CZ.net=0A>>=0A>>=0A>>=0A>>Sent from my iPad=0A>>On Apr 7, 2011,= at 11:53 AM, "Wolfgang" wrote:=0A>>Chris, have you co= nsidered what effect airframe vibration has on the position of the spool in= the pump and the problem in general ?=0A>>>=A0=0A>>>Wolfgang=0A>>>From: Ch= ris =0A>>>Sender: =0A>>= >Subject: Re: [LML] Re: LNC2 Gear Hydraulics =0A>>>Date: Wed, 06 Apr 2011 0= 7:38:35 -0400 =0A>>>To: lml@lancaironline.net =0A>>>I would like to exten= d the offer to the whole group. =A0I think the entire community would benef= it from understanding why some 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 check it out on the test stand and examine the = internal configuration.=0A>>>Chris Zavatson=0A>>>N91CZ=0A>>>360std=0A>>>www= .N91CZ.net --0-1581527968-1309195488=:75904 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
=
Wolfgang,
A simple visual examination of the actual parts installed= in such an offending pump would be the place to start. This could be as si= mple as an incorrect or missing part.  Without looking we may nev= er know.
 
Chris 
 

From: Wolfgang <Wolfgang@MiCom.net&= gt;
To: Chris Zavatson &= lt;chris_zavatson@yahoo.com>
Sen= t: Sunday, June 26, 2011 8:29 AM
Subject: Re: [LML] Re: LNC2 Gear Hydraulics
Interesting . . . but still leaves the que= stion of how some installations still manage to display the "fail to f= unction" problem.
 
Wolfgang
 
----- Original Message -----
Sent: Saturday, June 25, 2011 12:35 = PM
Subject: Re: [LML] Re: LNC2= Gear Hydraulics

Curiosity got the best of me.  Here are the peak = vibration values recorded today at the hydraulic pump measured on the axis 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 abou= t any other component on the pla= ne.
 
Chris Zavatson
N91CZ
360std
 

From: Wolfgang <Wolfgang@MiCom.net&= gt;
To: lml@lancaironlin= e.net
Sent: Friday, Apri= l 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 sim= ilar.
 
That's why I came up with the gear fix&nbs= p;module.
 
Wolfgang
 
----- Original Message -----
Sent: Wednesday, 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.<= /DIV>
Using o-ring 013-90 requires 70 g's to move the spool.<= BR>This includes the return force generated by the poppet springs (410462).=  
The difference between the two o-rings is durometer.  = I have been using the softer one without any problems.  The stiffer o-= ring (intended for pumps with back pressure 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 force for the spool and make sure it ha= s an o-ring installed.
 
Chris Zavatson
N91CZ
360std
<= BR>
From: Wolfgang <Wolfgang@MiCom.net&= gt;
To: lml@lancaironlin= e.net
Sent: Mon, April 1= 1, 2011 4:56:57 AM
Subject:<= /B> [LML] Re: LNC2 Ge= ar 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 pump. There have been many changes in it= 's production life and one of them was to make the spool symmetrical and ha= ve the relief circuit the same both ways.
 
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 thi= s the next time I have a pump opened up)  Could it be that a pump some= how ended up mounted such that it was subjected to some resonant frequency?=  Seems like a remote possibilty given all the variables an= d the mass of the pump.    How about wear and tear?  Perhaps sitting dry and idle for ten years would do it. &= nbsp;A missing O-ring or a spool that doesn't utilize an O-ring would allow= the spool to move very easily.  Parker does make spools that don't ev= en have O-rings.  Did these end up getting installed by chance?

Based on reports from the = LML, the behavior seems to be ra= ther binary.  On the one hand we have planes with over 1000 hours and = more than ten years of service that have never once had the spool move off = the poppet.  On the other hand, we have 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" <W= olfgang@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
=
=
<= /DIV>
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