X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 29 Jan 2013 10:55:40 -0500 Message-ID: X-Original-Return-Path: Received: from nm1.bullet.mail.ne1.yahoo.com ([98.138.90.64] verified) by logan.com (CommuniGate Pro SMTP 6.0.1) with ESMTPS id 6034957 for lml@lancaironline.net; Tue, 29 Jan 2013 10:03:44 -0500 Received-SPF: none receiver=logan.com; client-ip=98.138.90.64; envelope-from=chris_zavatson@yahoo.com Received: from [98.138.226.177] by nm1.bullet.mail.ne1.yahoo.com with NNFMP; 29 Jan 2013 15:03:08 -0000 Received: from [98.138.226.162] by tm12.bullet.mail.ne1.yahoo.com with NNFMP; 29 Jan 2013 15:03:08 -0000 Received: from [127.0.0.1] by omp1063.mail.ne1.yahoo.com with NNFMP; 29 Jan 2013 15:03:08 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 505837.39993.bm@omp1063.mail.ne1.yahoo.com Received: (qmail 99499 invoked by uid 60001); 29 Jan 2013 15:03:08 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Rocket-MIMEInfo:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=VTCHUQtWxnn0x4K6ckeO4xIjZkNly1th3P+OpE2oZGwz3/6OMzZpHHr1Cr5RxBVMc6YvGxz6qa2qZ0CKgEajIq/R6ivAEWVX9TAcpuO0Jw92mmEJb+K/ix2pY/zsglTZoXfXHWJ7Lp8tRW6jfyYp1Yv+ynENWlDTn6fporvwF1Q= ; X-YMail-OSG: zDuwVFQVM1mDAyg.B0mbOBvgNku83L3lDXql2FfMVi0fXnz IhuGNypmpJ3qpBA6Q9TIFWXs2mbN3mfFo4VOb24wCqF6jazvwrACJc0GvTgR .XMal4vWOCDoZvgxnblqaadAbplR8YvWfi3HcOO9lwYFlqpspw4.Wryn3.hC DZXE3r7haAvZa4gL44sTfBrBs_LHmB0hOx7aabyEFwzLcDXRdd5L4qYEqnME W9.Wo5vqf8kS7xwhLscbVq6SShHtuqpwAPyAKyJM91CD26ftebcakBae9fkb iXjRqg8.fKx5g4lOv0BoHUY4YO0Cz.37nBZGCSbOucud82bBnMkpEqmJ7MLz RaioaYG6eebrUjbxoFpeeGlEcJOISWvoD_wc2QfpKGa5utDbLnrXLr4xtEMQ LkbBrRVuNaUdNyvvkU.OYIoDz1uM5TdbyHc4CRtcQ7Sudc2AF16_9zJdz6Gx n_Etd9FjX.YQrxJdED.RKSGrVnYIbFSaN2o5Q_HML38nexG4OAUJerz0JvIi LgqperbRIGKgHH55j1HIVd4DJBd2j1wMM9YcT5ef3fFmSXcGxpVmctw3jnKj g9o_4k9wQU_GCmvnXB6j5Qnwahw-- Received: from [76.246.36.168] by web121601.mail.ne1.yahoo.com via HTTP; Tue, 29 Jan 2013 07:03:08 PST X-Rocket-MIMEInfo: 001.001,U2NvdHQsClllcCwgdGhlIGZhaWx1cmUgbW9kZXMgYXJlIGNvbXBsZXRlbHkgdW5yZWxhdGVkIHRvIGVhY2ggb3RoZXIuClRoZXJlIGlzIGEgc2Vjb25kIGZhaWx1cmUtdG8tcmV0cmFjdCBtb2RlLsKgIEluIGZhY3QsIGl0IGlzIHRoZSBvbmx5IG9uZSBJIGV4cGVyaWVuY2VkIGluIG15IHBsYW5lLsKgIEl0IHdhcyB3aXRoIHRoZSBvbGQgVkVQIHByZXNzdXJlIHN3aXRjaGVzLsKgIFRoZXkgd291bGQgc3RpY2sgb3BlbiBvbiBvY2Nhc3Npb24uwqAgVGhlbiB0aGUgcHJvYmxlbSBpcyBub3QgdG9vIG11Y2ggcHIBMAEBAQE- X-Mailer: YahooMailWebService/0.8.131.499 References: X-Original-Message-ID: <1359471788.95459.YahooMailNeo@web121601.mail.ne1.yahoo.com> X-Original-Date: Tue, 29 Jan 2013 07:03:08 -0800 (PST) From: Chris Zavatson Reply-To: Chris Zavatson Subject: Re: [LML] Re: Thermal influence on Hydraulic Pressure X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-1977980688-1094974880-1359471788=:95459" ---1977980688-1094974880-1359471788=:95459 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Scott,=0AYep, the failure modes are completely unrelated to each other.=0AT= here is a second failure-to-retract mode.=A0 In fact, it is the only one I = experienced in my plane.=A0 It was with the old VEP pressure switches.=A0 T= hey would stick open on occassion.=A0 Then the problem is not too much pres= sure, it is not having any.=A0=0AFailure to retract can be a bit more serio= us if in IMC or taking off at high density altitude.=0A=A0=0AThe failure to= extend can be fixed by simply raising the operating pressure of the low si= de circuit.=0AI have looked at pumps spanning the 95 to 2011 manufacturing = time frame.=A0 The only one that would lock up on the ground had spool retu= rn springs.=A0 Since the 70g rattle-your-spool controversy appeared, I have= also been measuring the spool resistance in every pump I get=A0my hands on= .=A0 -haven't found an outliers yet, but I will keep looking.=0A=A0=0AChris= Zavatson=0AN91CZ=0A360std 1,400hrs=0Ahttp://www.n91cz.net/=0A=A0 =0A=0A___= _____________________________=0A From: "Sky2high@aol.com" =0ATo: lml@lancaironline.net =0ASent: Tuesday, January 29, 2013 5:27 AM=0A= Subject: [LML] Re: Thermal influence on Hydraulic Pressure=0A =0A=0AChris,= =0A=0AWhile waiting for Wolfgang's answer, some 200/300 series pilots are = =0Abecoming concerned that they can't get the gear down when needed.=A0 Fir= st, =0ALorn's secondary problem is that he didn't look for the "gear down a= nd locked" =0Alights before landing.=A0 While the gear down pressure switch= =A0saw enough =0Apressure to=A0not allow the pump to start, the failure to = recognize that the =0Agear was not down contributed to the belly in landing= . =0A=0ATo allow people to be more comfortable about the hydro-electric sys= tem they =0Ashould be reminded of this =0A=0A1. The failure to=A0RETRACT th= e gear because of high pressure on both =0Asides is a problem because of th= e safe design.=A0=A0Opening the dump valve =0Adoesn't resolve the problem= =A0because the system is in a static state with =0Athe gear down and locked= .=A0 There are no physical=A0forces able to change =0Athe system condition = - no G-maneuvers, no slips or skids, nada. =0A=0A2. The failure to EXTEND t= he gear because of high pressure on both sides is =0Adifferent.=A0 Opening = the dump valve (allowing down side fluid to flow to the =0Aupside) will all= ow the gear to "emergency" extend because of gravity on the =0Amains=A0and = the nose gear gas spring.=A0 OK, maybe the nose gear might not =0Aextend al= l the way at 120 KIAS (max gear extension speed), but the pressure lock =0A= has been broken and the pump will start if the switch is down and the pump = =0Abreaker is closed.=A0 Close the dump valve to complete the process.=A0 A= s =0Aa matter of fact, assuming everything is normal and the gear down swit= ch is =0Aselected but nothing happens, it may merely require momentarily cr= acking the =0Adump valve to relieve the hydraulic constipation. =0A=0AFaili= ng to retract is a nuisance. =A0Failing to extend is, uh, more =0Aserious, = but resolvable. =0A=0AScott Krueger AKA Grayhawk =0A=0AIn a message dated = 1/29/2013 6:54:27 A.M. Central Standard Time, =0Achris_zavatson@yahoo.com w= rites: =0AWolfgang, =0A>I seem to recall you dismissed the idea of a three= -way valve previously. =0A><- - How= ever it requires changing the dump valve, running a return line and pump m= odification (replace the reservoir). =0A>.................................= .. =0A>Wolfgang>> =0A><<..........Automatic action by my module can preve= nt these problems for both up and down gear operation. =0A>Wolfgang>> =0A>= =A0 =0A>Could you please explain how your module will prevent the gear ext= ension lock-up failures.=A0 Recall Lorn's photo after his extension failur= e and gear up landing.=A0 Both pressure gauges showed around 500 psi.=A0 T= he system is hydraulically locked with one switch open and one closed.=A0 = =0A>Chris Zavatson =0A>N91CZ =0A>360std, 1,400 hrs =0A>http://www.n91cz.net= / =0A>=A0 =0A>=0A>________________________________=0A>From: Wolfgang =0A>To: lml@lancaironline.net =0A>Sent: Saturday, January 2= 6, 2013 11:24 AM=0A>Subject: [LML] Re: Thermal influence on Hydraulic Pre= ssure=0A>=0A>=0A> =0A>This has been covered at great length before. Some t= ake the position that "real pilots" don't need anything but=A0the dump val= ve. =0A>I have proposed two answers, =0A>1) replace the dump valve that onl= y opens a port between the HI and LO sides with a dump valve that dumps b= ack to the pump reservoir. =0A>2) install a small electric module I make ac= ross the pressure switches that=A0runs the pump to=A0relieve the over pre= ssure in the "wrong" line automatically. =0A>=A0 =0A>Wolfgang =0A>----- Ori= ginal Message ----- =0A>>From: Charles Brown =0A>>To: lml@lancaironline.= net =0A>>Sent: Saturday, January 26, 2013 2:07 AM =0A>>Subject: Re: [LML]= Re: Thermal influence on Hydraulic Pressure =0A>>=0A>> =0A>>This has happ= ened to me even at the beginning of a flight, if the temps in the hangar h= ave gone from cold on a previous day, to warm on flight day. =A0I guess co= ld temps shrink the fluid and suck more from the reservoir into the lines,= and when it warms, the pressure builds on both sides of the system, so th= at the "up" and "down" pressure switches are both open and the gear won't = move until I pop the bleed valve. =0A>>=0A>> =0A>>Nasty when the gear won't= retract just after blasting off into a low overcast. =0A>>=0A>> =0A>>Char= ley Brown =0A>>Legacy #299 =A0200 hr=0A>>=0A>>On Jan 25, 2013, at 7:23 AM, = randy snarr wrote: =0A>>=0A>> =0A>>. I dont like having to open the dump va= lve but it is necessary once in a while especially when it is cold. The p= ressures on both sides of the system climb due to the engine heat and the = gear sometimes will not move without dumping the pressure. =0A>>=0A>=0A>=0A= >=0A>--=0A>For =0A archives and unsub =0A http://mail.lancaironline.net:8= 1/lists/lml/List.html=0A> ---1977980688-1094974880-1359471788=:95459 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Scott,
Yep, the failure modes are completely unrelated to each other.
There is a second failure-to-retract mode.  In fac= t, it is the only one I experienced in my plane.  It was with the old = VEP pressure switches.  They would stick open on occassion.  Then= the problem is not too much pressure, it is not having any. 
Failure to retract can be a bit more serious if in IMC or ta= king off at high density altitude.
 
The failure to extend can be fixed by simply raising the opera= ting pressure of the low side circuit.
I have looked= at pumps spanning the 95 to 2011 manufacturing time frame.  The only = one that would lock up on the ground had spool return springs.  Since the 70g rattle-your-spool controversy appeared, I have also been mea= suring the spool resistance in every pump I get my hands on.  -ha= ven't found an outliers yet, bu= t I will keep looking.
 
Chris Zavatson
N91CZ
360std 1,400hrs
 
From: "S= ky2high@aol.com" <Sky2high@aol.com>
To: lml@lancaironline.net
Sent: Tuesday, January 29, 2013 5:27 AM
Subject: [LML] Re: Thermal influe= nce on Hydraulic Pressure

=0A
=0A=0A =0A =0A
=0A
Chris,
=0A
 
=0A<= div>While waiting for Wolfgang's answer, some 200/300 series pilots are =0A= becoming concerned that they can't get the gear down when needed.  Fir= st, =0ALorn's secondary problem is that he didn't look for the "gear down a= nd locked" =0Alights before landing.  While the gear down pressure swi= tch saw enough =0Apressure to not allow the pump to start, the fa= ilure to recognize that the =0Agear was not down contributed to the belly i= n landing.
=0A
 
=0A
To allow people to be more comf= ortable about the hydro-electric system they =0Ashould be reminded of this<= /div>=0A
 
=0A
1. The failure to RETRACT the gear be= cause of high pressure on both =0Asides is a problem because of the safe de= sign.  Opening the dump valve =0Adoesn't resolve the problem = ;because the system is in a static state with =0Athe gear down and locked.&= nbsp; There are no physical forces able to change =0Athe system condit= ion - no G-maneuvers, no slips or skids, nada.
=0A
 
=0A=
2. The failure to EXTEND the gear because of high pressure on both sid= es is =0Adifferent.  Opening the dump valve (allowing down side fluid = to flow to the =0Aupside) will allow the gear to "emergency" extend because= of gravity on the =0Amains and the nose gear gas spring.  OK, ma= ybe the nose gear might not =0Aextend all the way at 120 KIAS (max gear ext= ension speed), but the pressure lock =0Ahas been broken and the pump will s= tart if the switch is down and the pump =0Abreaker is closed.  Close t= he dump valve to complete the process.  As =0Aa matter of fact, assumi= ng everything is normal and the gear down switch is =0Aselected but nothing= happens, it may merely require momentarily cracking the =0Adump valve to r= elieve the hydraulic constipation.
=0A
 
=0A
Failing= to retract is a nuisance.  Failing to extend is, uh, more =0Aserious,= but resolvable.
=0A
 
=0A
Scott Krueger AKA Grayha= wk
=0A
 
=0A
=0A
In a message dated 1/29/2013 6:= 54:27 A.M. Central Standard Time, =0Achris_zavatson@yahoo.com writes:
= =0A
=0A
=0A <= div id=3D"yiv1832323286">=0A
=0A
=0A
Wolfgang,
=0A
I seem = to recall you dismissed the idea of =0A a three-way valve previously. =0A
=0A
<<That's a sound and =0A positive fix.
=0A
- - However it re= quires changing =0A the dump valve, running a return line and pump modific= ation (replace the =0A reservoir).
=0A
.................................= ..
=0A
Wolfgang>>= ;
=0A
<= font id=3D"yiv1832323286yui_3_7_2_20_1359357037910_54" face=3D"Times New Ro= man">
=0A
=0A <<..........Automatic =0A acti= on by my module can prevent these problems for both up and down gear =0A o= peration.
=0A
Wolfgang>>=
=0A
&= nbsp;
=0A
Could you please explain how your module =0A will prevent t= he gear extension lock-up failures.  Recall Lorn's photo =0A after hi= s extension failure and gear up landing.  Both pressure gauges =0A sh= owed around 500 psi.  The system is hydraulically locked with one =0A = switch open and one closed.
=0A
 =0A
Chris Zavatso= n
=0A
N91CZ
=0A
360std, 1,400 hrs
=0A
http= ://www.n91cz.net/
=0A
=0A
 
=0A
=0A
=0A
=0A
From: Wolfgang =0A <Wolfgang@MiCom= .net>
To: lml@lancai= ronline.net
Sent: Satu= rday, January 26, 2013 11:24 =0A AM
Subject: [LML] Re: Thermal =0A influence on Hydraulic Pressu= re

=0A
=0A = =0A=0A
=0A
This has been covere= d at great length before. =0A Some take the position that "real pilots" do= n't need anything but the =0A dump valve.
=0A
I have proposed two answers,
=0A 1) replace the dump valve that only open= s a port =0A between the HI and LO sides with a dump valve =0A that dumps back to the pump reservoir.<= /div>=0A
2) install a small electric = module I make across =0A the pressure switches that runs the pump to&= nbsp;relieve the over =0A pressure in the "wrong" line automatically.
=0A
 
=0A
= Wolfgang
=0A
=0A
----- Original Message -----
=0A =
From: Charles =0A Brown
=0A
To: lml@lancaironline.net <= /div>=0A
Sent: Satu= rday, January 26, 2013 2:07 =0A AM
=0A
Subject: Re: [LML] Re: Thermal =0A influence= on Hydraulic Pressure
=0A

=0A
This has happ= ened to me even at the beginning of a flight, if the temps =0A in the ha= ngar have gone from cold on a previous day, to warm on flight day. =0A &= nbsp;I guess cold temps shrink the fluid and suck more from the reservoir = =0A into the lines, and when it warms, the pressure builds on both sides= of the =0A system, so that the "up" and "down" pressure switches are bo= th open and the =0A gear won't move until I pop the bleed valve.
= =0A

=0A
Nasty when the gear won't retract just af= ter blasting off into a low =0A overcast.
=0A

=0A=
Charley Brown
=0A=0A
Legacy #299  200 hr
=0A
=0A
On Jan 25, 2013, at 7:23 AM, randy snarr wrote:=0A
=0A
=0A
. I dont like having to open the dump valve =0A = but it is necessary once in a while especially when it is cold. The =0A = pressures on both sides of the system climb due to the engine heat and th= e =0A gear sometimes will not move without dumping the pressure.
= =0A
=0A
=0A





--For =0A archives and unsub =0A http://mail.lancaironline.net:81/lists/l= ml/List.html


 
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