X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 28 Apr 2014 12:04:12 -0400 Message-ID: X-Original-Return-Path: <2thman1@gmail.com> Received: from mail-qa0-f50.google.com ([209.85.216.50] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6849643 for lml@lancaironline.net; Mon, 28 Apr 2014 08:15:26 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.216.50; envelope-from=2thman1@gmail.com Received: by mail-qa0-f50.google.com with SMTP id s7so5053723qap.9 for ; Mon, 28 Apr 2014 05:14:49 -0700 (PDT) X-Received: by 10.224.43.202 with SMTP id x10mr32220973qae.33.1398687289547; Mon, 28 Apr 2014 05:14:49 -0700 (PDT) X-Original-Return-Path: <2thman1@gmail.com> Received: from [10.126.1.251] (mobile-166-171-059-016.mycingular.net. [166.171.59.16]) by mx.google.com with ESMTPSA id a7sm32827452qas.2.2014.04.28.05.14.48 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 28 Apr 2014 05:14:48 -0700 (PDT) Subject: Re: [LML] Re: Gear Down...INOP References: From: John Barrett <2thman1@gmail.com> Content-Type: multipart/alternative; boundary=Apple-Mail-C9769B34-CC9D-45FE-AD66-BC76AEE5966B X-Mailer: iPhone Mail (11B651) In-Reply-To: X-Original-Message-Id: X-Original-Date: Mon, 28 Apr 2014 08:14:48 -0400 X-Original-To: Lancair Mailing List Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-C9769B34-CC9D-45FE-AD66-BC76AEE5966B Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Marv,=20 it's always most appreciated and informative to have free argument of opposi= ng ideas even when the subject does not apply to my model of aircraft. When i= t turns to invective like this post, the value is lost and it starts to beco= me a nuisance. My $.02 John Barrett N31VP Sent from my iPhone > On Apr 28, 2014, at 7:59 AM, "Wolfgang" wrote: >=20 > Chris, > =20 > I remain unconvinced with your theory. You have suggested that the pump wi= ll somehow shut down immediately after it has started up due to some pressur= e pulse. The mechanisim of which you have yet to clarify, let alone demonstr= ated. > =20 > I'm tired of your kibitzing and since you have proven that you can't let i= t go, I will and leave you to humor yourself. > =20 > Wolfgang > =20 > ----- Original Message ----- > From: Chris Zavatson > To: lml@lancaironline.net > Sent: Saturday, April 26, 2014 1:28 PM > Subject: Gear Down...INOP >=20 > Wolfgang, >=20 > <<=E2=80=9CI believe in redundancy and it looks like you don't=E2=80=A6.=E2= =80=9D>> >=20 > I am a big proponent of redundancy. That is redundancy defined as a true b= ack-up to an otherwise trouble-free system. >=20 > First, I have redundant switches to power the pump solenoids. This allows= me to raise and lower the gear in case of the failure of either of the pres= sure switches. It doesn=E2=80=99t happen very often, but it does happen - t= wice in 17 years of flying my 360.=20 >=20 > I also have redundant gear down indications. Two completely separate syst= ems, separate switches, separate wires and separate indicators. The second s= et of switches is mounted directly on the over-center links. >=20 > I even carry two iPads and a iPhone - just in case >=20 > <<=E2=80=9CThe pressure pulse you're talking about will subside (glad you a= gree) and as it does, because the cylinder is only partially extended, the c= ylinder will continues to extend, the low switch will close again, and enabl= e the pump to continue . .=E2=80=9D>> >=20 > The part you seem to be missing here is that the momentary pulse is not di= rectly turning off the pump. Thus when the pulse subsides, the pump doesn=E2= =80=99t just spring back to life. The pulse pushes the spool in the wrong d= irection -against the pump flow. This locks the poppet that the pump just o= pened up a fraction of a second earlier. When this happens, the high side b= egins to pressurize along with the low side. As soon as both sides reach th= e low side pressure setting, the pump is turned off. This is why you see bo= th high and low circuits pressurized to the same value in Lorn=E2=80=99s pho= to. >=20 > To prevent this, the low side pressure settings should be raised. 800 psi= has proven sufficient. The high volume gear pump will reduce the size of t= he pulse since the higher volume pump is able to absorb incoming fluid at a h= igher rate. >=20 > I highly recommend pressure gauges for both high and low circuit be instal= led in a location visible to the pilot. The state of the system can always b= e verified. One can immediately diagnose any in-flight problem. Leaks can b= e caught early. And adjusting pressure settings is no longer guess work. > Chris Zavatson > N91CZ > 360std > www.N91CZ.net --Apple-Mail-C9769B34-CC9D-45FE-AD66-BC76AEE5966B Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Marv, 

i= t's always most appreciated and informative to have free argument of opposin= g ideas even when the subject does not apply to my model of aircraft. When i= t turns to invective like this post, the value is lost and it starts to beco= me a nuisance.

My  $.02
John Barrett=
N31VP

Sent from my iPhone

On Apr 28, 2= 014, at 7:59 AM, "Wolfgang" <Wolfga= ng@MiCom.net> wrote:

Chris,
 
I remain unconvinced with your theory. Y= ou have=20 suggested that the pump will somehow shut down immediately after it has star= ted=20 up due to some pressure pulse. The mechanisim of which you have yet to clari= fy,=20 let alone demonstrated.
 
I'm tired of your kibitzing and since y= ou have=20 proven that you can't let it go, I will and leave you to humor=20 yourself.
 
Wolfgang
 
----- Original Message -----
Sent: Saturday, April 26, 2014 1:28= =20 PM
Subject: Gear Down...INOP

Wolfgang,

<<=E2=80=9CI=20 believe in redundancy and it looks like you=20 don't=E2=80=A6.=E2=80=9D>>

I=20 am a big proponent of redundancy. =20= That is redundancy defined as a true back-up to an otherwise=20 trouble-free system.

First, I have redundant switches to power the pump= solenoids.  This allows me to= raise and lower the=20 gear in case of the failure of either of the pressure switches.  It doesn=E2=80=99t happen very often, b= ut it=20 does happen - twice in 17 years of flying my 360. 

I=20 also have redundant gear down indications.  The second set of switches is mounted=20 directly on the over-center links.

I=20 even carry two iPads and a iPhone - just in case

<<=E2=80=9CThe=20 pressure pulse you're talking about will subside (glad you agree) and as i= t=20 does, because the cylinder is only partially extended, the cylinder w= ill=20 continues to extend, the low switch will close again, and enable the pump t= o=20 continue . .=E2=80=9D>>

The=20 part you seem to be missing here is that the momentary pulse is not direct= ly=20 turning off the pump.  Thus w= hen=20 the pulse subsides, the pump doesn=E2=80=99t just spring back to life.  The pulse pushes the spool in th= e=20 wrong direction -against the pump flow.&= nbsp;=20 This locks the poppet that the pump just opened up a fraction of a=20= second earlier.  When this=20= happens, the high side begins to pressurize along with the low side.  As soon as both sides reach the low= =20 side pressure setting, the pump is turned off.  This is why you see both high and low=20 circuits pressurized to the same value in Lorn=E2=80=99s photo.

To=20 prevent this, the low side pressure settings should be raised.  800 psi has proven sufficient.  The high volume gear pump will reduce=20 the size of the pulse since the higher volume pump is able to absorb incom= ing=20 fluid at a higher rate.

I=20 highly recommend pressure gauges for both high and low circuit be installe= d in=20 a location visible to the pilot. =20= The state of the system can always be verified.  One can immediately diagnose any=20 in-flight problem.  Leaks ca= n be=20 caught early.  And adjusting= =20 pressure settings is no longer guess work.
Chris=20 Zavatson
N91CZ
360std
= --Apple-Mail-C9769B34-CC9D-45FE-AD66-BC76AEE5966B--