X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 21 Feb 2012 09:01:23 -0500 Message-ID: X-Original-Return-Path: Received: from nm3.bullet.mail.sp2.yahoo.com ([98.139.91.73] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with SMTP id 5407065 for lml@lancaironline.net; Mon, 20 Feb 2012 19:18:10 -0500 Received-SPF: none receiver=logan.com; client-ip=98.139.91.73; envelope-from=chris_zavatson@yahoo.com Received: from [98.139.91.69] by nm3.bullet.mail.sp2.yahoo.com with NNFMP; 21 Feb 2012 00:17:33 -0000 Received: from [72.30.22.202] by tm9.bullet.mail.sp2.yahoo.com with NNFMP; 21 Feb 2012 00:17:33 -0000 Received: from [127.0.0.1] by omp1064.mail.sp2.yahoo.com with NNFMP; 21 Feb 2012 00:17:33 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 296797.80016.bm@omp1064.mail.sp2.yahoo.com Received: (qmail 94526 invoked by uid 60001); 21 Feb 2012 00:17:32 -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=b3p15KZ/k3igwXfyG1+GCPN4amV8IQr9my1Obj5HbRyV8sQSngpeV8l3C+gO7k4AoMHfvarvTLZXc4Z8WpnelKHrgxeU3huOomdIYR6Lw6XSPP72WY4iQ80F5fIwdlvHS66seWZN5xJmnXN6j2ND4w4QnqHhxsh3XwhALFtPFvs=; X-YMail-OSG: bCiBfWsVM1nYIl5RvVAt755us7deE_5681yikX7pJL9iCk1 2Oz49RuNkwoz5jABAAFOmESGCbkQg9g1IKZCR9MUV_EpyO7wkA.I7ryZJSge mArdb4.lgu.smcXqLjhd89QQ.NgKvtRHMdpsnro411yl.OyB0btOoK0S_nLG W8hY5tOkeCCn3QDIIWSDIixGjhV8bjCzxFlX764lRYs.U8CNJSkVl3PCfxkw R_ll0Y_D_xbbmpsHKEpT1WeGJyhhLD9IQ6ksQDJ8Xeh8_7VZowwieJiat.67 _aS9ETDDvbgNbQULlEVEsZadPRL60NQdQYqbbKR3CrJv3MPuyvhz_HFOMSHE koinW6wqkk7P9Yn86YnBSNYH35in3U4p6V8YB92CeAJ177ezNGPJKBJCFcqc xt_lr_B2uqF6AuZiNN3LeZIHmWN9SNFbUllxaVf0Q7e1gBR3yAEQra.ewt6T D37UE4pL2O93RGVTlgR2MhA4sYI6UrX8zKOHgz5z4Ta0ShxU8g8PjHgQxMHN 7.dg1uwRowWrQR304_qaapAF7yR0yu1_Dk0YdPdCyrHc- Received: from [76.246.36.224] by web36902.mail.mud.yahoo.com via HTTP; Mon, 20 Feb 2012 16:17:32 PST X-Mailer: YahooMailWebService/0.8.116.338427 References: X-Original-Message-ID: <1329783452.84393.YahooMailNeo@web36902.mail.mud.yahoo.com> X-Original-Date: Mon, 20 Feb 2012 16:17:32 -0800 (PST) From: Chris Zavatson Reply-To: Chris Zavatson Subject: Re: [LML] Re: 320/360 Hydraulic Pressure Switch X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-2114655128-1108911585-1329783452=:84393" ---2114655128-1108911585-1329783452=:84393 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable " . . . you can only override one pressure switch at a time or overload the= system.=0AYou need one switch each for the up and down. In the event of a = problem you have to make sure you push the right switch"...=0A=A0=0AOverloa= d what exactly?=A0 The gear selector determines which pressure switch is po= wered.=A0 If you jumper across an unpowered switch, nothing happens.=A0 =0A= While I do=A0not advocate putting in switches to mask a pump problem that s= hould really be investigated and=A0fixed at the source, momentary switches = have other benefits.=A0 =0A=A0=0A1.=A0 Checking the relief valve settings i= n the pump.=A0 By holding down the switch, one can see the relief valve set= ting of the pump.=0A=0A2.=A0=A0Back-up for=A0a failed pressure switch.=A0 T= his was more common with the VEP switches, but current version is not immun= e.=A0=0A3.=A0 Recharging the system on demand - The hysteresis loop on the = pressure switches is quite large.=A0 The gear can start to sag before the p= ressure switch recharges the system.=A0 This is=A0more of an=A0issue for th= e Outback Gear due to the higher aerodynamic loads pulling on the gear.=A0= =0A=A0=0AWith=A0automation and complexity come new failure modes.=A0=A0Give= the pilot enough information about the state of the aircraft systems to fi= gure out what happened and enough controls to solve the problem.=0ALast sum= mer when the high=A0pressure switch went out, the pump shut off before the = gear was all the way up.=A0 Higher than normal air noise was the first clue= .=A0 A quick look at the pressure gauges revealed the high side at only 800= psi.=A0 =A0The momentary switch pulled the gear=A0the rest of=A0the way up= .=A0=A0 Examination of the pressure switch uncovered intermittent electrica= l=A0contact within the switch when pressurized.=A0=0A=A0=0AChris Zavatson= =0AN91CZ=0A360std=0Awww.N91CZ.net=0A=A0=0A=A0=0AFrom: Wolfgang =0ATo: lml@lancaironline.net =0ASent: Monday, February 20, 2012 4:5= 8 AM=0ASubject: [LML] Re: 320/360 Hydraulic Pressure Switch=0A=0AYes, that = would be easy . . . except . . . you can only override one pressure switch = at a time or overload the system.=0AYou need one switch each for the up and= down. In the event of a problem you have to make sure you push the right s= witch.=0AIf you come up with some more complicated wiring, you could make i= t work with only one switch for both up and down but you still have to push= the button if something isn't working as required.=0A. . . or . . . you co= uld put in a completely automatic system . . .=0A=0AWolfgang=0A=0A----- Ori= ginal Message ----- From: "Greenbacks, UnLtd." =0ATo: =0ASent: Friday, February 17, 2012 1:07 PM=0ASubject: R= e:320/360 Hydraulic Pressure Switch=0A=0A=0ASeems to me the simplest and le= ast expensive option would be to install a momentary on switch in the cockp= it to override and close the open pressure switches.=0A=0AJust my 2 cents.= =0A=0AAngier Ames=0AN3ZQ =0A=0A=0A--=0AFor archives and unsub http://mail.l= ancaironline.net:81/lists/lml/List.html ---2114655128-1108911585-1329783452=:84393 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
" . . . you can only override one pressure switch at= a time or overload the system.
You need one switch each for the up and = down. In the event of a problem you have to make sure you push the right sw= itch"...
 
Overload what exactl= y?  The gear selector determines which pressure switch is powered.&nbs= p; If you jumper across an unpo= wered switch, nothing happens. 
While I do not = advocate putting in switches to mask a pump problem that should really be i= nvestigated and fixed at the source, momentary switches have other ben= efits. 
 
1.  Checking th= e relief valve settings in the pump.  By holding down the switch, one = can see the relief valve setting of the pump.
2.  Back-up for a failed pressure= switch.  This was more common with the VEP switches, but current vers= ion is not immune<= /SPAN>. 
3.  Recharging = the system on demand - The hysteresis loop on the pressure switches is quit= e large.  The gear can start to sag before the pressure switch recharges the syst= em.  This is more of an issue for the Outback Gear due to th= e higher aerodynamic loads pulling on the gear. 
 
With automation= and complexity come new failure modes.  Give the pilot enough in= formation about the state of the aircraft systems to figure out what happen= ed and enough controls to solve the problem.
Last summer when the= high pressure switch went out, the pump shut off before the gear was = all the way up.  Higher than normal air noise was the first clue. = ; A quick look at the pressure gauges revealed the high side at only 800 ps= i.   The momentary switch pulled the gear the rest of t= he way up.   Examination of the pressure switch uncovered intermi= ttent electrical contact within the switch when p= ressurized. 
 
Chris Zavatson
N91CZ
360std
 
 
From:= Wolfgang <Wolfgang@MiCom.net>
To: lml@lancaironline.net
Sent: Monday, February 20, 2012 4:58 AM
Subject: [LML] Re: 320/360 Hydra= ulic Pressure Switch

Yes, that would be easy . . . exce= pt . . . you can only override one pressure switch at a time or overload th= e system.
You need one switch each for the up and down. In the event of = a problem you have to make sure you push the right switch.
If you come u= p with some more complicated wiring, you could make it work with only one switch for b= oth up and down but you still have to push the button if something isn't wo= rking as required.
. . . or . . . you could put in a completely automati= c system . . .

Wolfgang

----- Original Message ----- From: "G= reenbacks, UnLtd." <N4ZQ@VERIZON.NET>
To: <lml@lancairo= nline.net>
Sent: Friday, February 17, 2012 1:07 PM
Subject: Re= :320/360 Hydraulic Pressure Switch


Seems to me the simplest and = least expensive option would be to install a momentary on switch in the coc= kpit to override and close the open pressure switches.

Just my 2 cen= ts.

Angier Ames
N3ZQ


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