X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 27 Jun 2011 12:16:11 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with ESMTP id 5033971 for lml@lancaironline.net; Mon, 27 Jun 2011 11:03:05 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.125; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=5asQ6euaRPJxDdFxwvXsn6JDb7fmFbz8qWDLMfa45gU= c=1 sm=0 a=ttCsPuSJ-FAA:10 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=Ia-xEzejAAAA:8 a=ndVRne3UAAAA:8 a=rTjvlri0AAAA:8 a=5FIZSGrRAAAA:8 a=CjxXgO3LAAAA:8 a=o9pwoDCwYLlkWRg0FAMA:9 a=Hogdvp4QZaWJ376lfMkA:7 a=wPNLvfGTeEIA:10 a=ILeVjEvywfEA:10 a=wR8WdYEwGqoA:10 a=EzXvWhQp4_cA:10 a=Dr9Wx-Q63l4A:10 a=rC2wZJ5BpNYA:10 a=TMjjPy9xdtoESF2-VfIA:9 a=pFf0PTBdKeapJ8qswDYA:7 a=tXsnliwV7b4A:10 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1716] helo=lobo) by hrndva-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 35/70-24893-68B980E4; Mon, 27 Jun 2011 15:02:31 +0000 X-Original-Message-ID: <001101cc34db$398484d0$6401a8c0@lobo> From: "Wolfgang" X-Original-To: Subject: Re: [LML] Re: LNC2 Gear Hydraulics X-Original-Date: Mon, 27 Jun 2011 11:02:25 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000E_01CC34B9.B24A4E30" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_000E_01CC34B9.B24A4E30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Interesting . . . but still leaves the question of how some = installations still manage to display the "fail to function" problem. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 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 about any = other component on the plane. Chris Zavatson N91CZ 360std www.N91CZ.com From: Wolfgang 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 landing 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 -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 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 = possibility 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 from 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 generated by the poppet springs = (410462). =20 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 has an o-ring = installed. Chris Zavatson N91CZ 360std www.N91CZ.net From: Wolfgang 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 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. Wolfgang Wolfgang, Yes, I have considered this. The spool with O-ring is a very tight = fight. While I have not tried to measure the force to move it, I would = 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 allow 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 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 there 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 simultaneously. 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. I am = optimistic the difference will be quite obvious upon inspection. =20 Chris Zavatson N91CZ 360std www.N91CZ.net Sent from my iPad On Apr 7, 2011, at 11:53 AM, "Wolfgang" wrote: Chris, have you considered what effect airframe vibration has on = the position of the spool in the pump and the problem in general ? Wolfgang From: Chris =20 Sender: =20 Subject: Re: [LML] Re: LNC2 Gear Hydraulics=20 Date: Wed, 06 Apr 2011 07:38:35 -0400=20 To: lml@lancaironline.net=20 =20 =20 I would like to extend the offer to the whole group. I = think the entire community would benefit from understanding why some = pumps are allowing the system to lock up. If 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. Chris Zavatson N91CZ 360std www.N91CZ.net=20 ------=_NextPart_000_000E_01CC34B9.B24A4E30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Interesting . . . but still leaves the = question of=20 how some installations still manage to display the "fail = to function"=20 problem.
 
Wolfgang
 
----- Original Message -----
From:=20 Chris=20 Zavatson
Sent: Saturday, June 25, 2011 = 12:35=20 PM
Subject: Re: [LML] Re: LNC2 = Gear=20 Hydraulics

Curiosity got = the best of=20 me.  Here are the peak vibration values recorded today = at the=20 hydraulic pump measured on the axis of the = spool=20 valve.
Start up:  = +/- 1.3=20 g
Take off:  = +/- 0.3=20 g
Cruise:  = +/- 0.1=20 g
Descent:  = +/- 0.1=20 g
Landing:  = +/- 0.6=20 g
It would appear = the O-ring=20 has more design margin than just about any other component on the plane.
 
Chris = Zavatson
N91CZ
360std
www.N91CZ.com
 

From: Wolfgang=20 <Wolfgang@MiCom.net>
To: = lml@lancaironline.net
Sent: Friday, April 15, 2011 = 10:11=20 AM
Subject: [LML] = Re: LNC2 Gear = Hydraulics
From a design point of view, I still = have a big=20 concern about relying on the friction from an O-ring to keep the = landing gear=20 functioning properly. Vibration levels can exceed 70 G's. I would be = much=20 happier with a spring loaded ball detent or something similar.
 
That's why I = came up with the=20 gear fix module.
 
Wolfgang
 
----- Original Message -----
To: lml@lancaironline.net =
Sent: = Wednesday,=20 April 13, 2011 8:25 AM
Subject: Re: [LML] Re: LNC2 Gear Hydraulics

A symmetric back-pressure circuit and spool will eliminate the=20 possibility of installing the spool backwards as happened with pumps = manufactured in about the '96 through '98 time frame.  The = spool must=20 still remain in place after the pump shuts down to prevent both high = and low=20 circuits from 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=20 force generated by the poppet springs (410462). 
The difference between the two o-rings is durometer.  I have been using the = softer one=20 without any problems.  The stiffer o-ring (intended for pumps = with back=20 pressure circuits) should leave no doubt.  The first thing to = do with a=20 pump that has a history of locking up both sides is to measure the = return=20 force for the spool and make sure it has an o-ring installed.
 
Chris Zavatson
N91CZ
360std

From: Wolfgang=20 <Wolfgang@MiCom.net>
To: = lml@lancaironline.net
Sent: Mon, April 11, 2011 = 4:56:57=20 AM
Subject: [LML] = Re: LNC2 Gear = Hydraulics
When I first got into this problem = with the=20 hydraulic pumps last year, I had a few conversations with the = product=20 manager of the Oildyne 108=20 pump. There have been many changes in it's production life and one = of them=20 was to make the spool symmetrical and have the relief circuit the = same both=20 ways.
 
Wolfgang
Wolfgang,
Yes, I have considered this.  The spool with O-ring is a = very=20 tight fight.  While I have not tried to measure the force to = move it, I=20 would estimate something over 50 g's to move it (I'll measure this the next = time I=20 have a pump opened up)  Could it be that a pump somehow ended = up=20 mounted such that it was subjected to some resonant frequency? =  Seems=20 like a remote possibilty given=20 all the variables and the mass of the pump.    How about = wear and=20 tear?  Perhaps sitting dry and idle = for ten=20 years would do it.  A missing O-ring or a spool that doesn't = utilize an=20 O-ring would allow the spool to move very easily.  Parker does = make=20 spools that don't even have O-rings.  Did these end up getting=20 installed by chance?

Based on reports = from the=20 LML, the behavior seems to be rather binary.  On the one hand = we have=20 planes with over 1000 hours and more than ten years of service that = have=20 never once had the spool move off the poppet.  On the other = hand, we=20 have planes with circuits that lock up right out of the box (put = into=20 service).
This leads me to = believe=20 there is a difference in configuration.  The easiest way to = verify this=20 is to simply open up a pump that is known to lock up hi and low = circuits=20 simultaneously.

While I have opened up several pumps (primarily to flip around = spool=20 valves), I have not yet worked on one that had this lock up issue. =  I=20 am optimistic the difference will be quite obvious upon inspection.=20  

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=20 airframe vibration has on the position of the spool in the pump = and the=20 problem in general ?
 
Wolfgang
From: Chris = <chris_zavatson@yahoo.com<= /A>>
Sender: <marv@lancaironline.net&= gt;
Subject: Re: [LML] = Re: LNC2 = Gear=20 Hydraulics
Date: Wed, 06 Apr = 2011=20 07:38:35 -0400
To: lml@lancaironline.net
I would like to extend the offer to the whole group. =  I=20 think the entire community would benefit from understanding = why some=20 pumps are allowing the system to lock up.  If anyone = has a pump=20 that exhibits this behavior and could part with it for a = week, I am=20 willing to check it out on the test stand and examine the = internal=20 configuration.
Chris Zavatson
N91CZ
360std
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