X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 31 Jan 2013 01:45:37 -0500 Message-ID: X-Original-Return-Path: Received: from nm20.access.bullet.mail.mud.yahoo.com ([66.94.237.221] verified) by logan.com (CommuniGate Pro SMTP 6.0.1) with ESMTPS id 6037857 for lml@lancaironline.net; Wed, 30 Jan 2013 21:30:14 -0500 Received-SPF: neutral receiver=logan.com; client-ip=66.94.237.221; envelope-from=browncc1@verizon.net Received: from [66.94.237.198] by nm20.access.bullet.mail.mud.yahoo.com with NNFMP; 31 Jan 2013 02:29:38 -0000 Received: from [98.138.85.46] by tm9.access.bullet.mail.mud.yahoo.com with NNFMP; 31 Jan 2013 02:29:38 -0000 Received: from [127.0.0.1] by smtp103.vzn.mail.ne1.yahoo.com with NNFMP; 31 Jan 2013 02:29:38 -0000 X-Yahoo-Newman-Id: 97458.7672.bm@smtp103.vzn.mail.ne1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: 6y98R14VM1lVikkZxC2ulJGskPmuVGRkQEiXq_9BuMxAPvz egiJHHyHzjY3qx9g9JS8s_bJwLwkMgeW_oC82wvbHWtN90ZpD89BfdmLqNqz lOG7SrpRTo19p580rx4icTMYW4jkmZzelK_xjraQsyI8EEH_zg3ZCa1nLlJb tmvBQM6dmo6jjalFigCuBoXYZVo_md7EMAvtixvr16NE_cTTkTFFsw.kEwai vc2BcRVhBoPC3OMIe6PuU2wKwBPmMKNHqBinOVgY8RVQ4iStmfd8UZ6_Opa8 u5nC6rTMWjnmYFm1smXFLviX88l_461wovMhPBS_fnQHzYyxMCytu..UO_qs FFl1LYGZpf5rN4tRUaBx2GpuGWKfvJwnyZIHFB9.zFV08VD7ErEyKI4XZwSS Fsuu0te5hxWyjNQOYX.eorxxCa3JJf11Phv_gfbDftgeyyoL1LeH_NwzdIK8 PnNxbFrNbZierh9mjmWZvtQlRB7SosUFnLleWv0xbcoxifGR_h2xuNC7i1eU oVfq_WPD0r.RiWFswRzFs X-Yahoo-SMTP: F49l9g6swBC0R9n8vJIbm7Tf3P8Xlmia8rHIwTlO__Ml Received: from chass-imac-2.home (browncc1@72.64.105.53 with plain) by smtp103.vzn.mail.ne1.yahoo.com with SMTP; 31 Jan 2013 02:29:38 +0000 UTC From: Charles Brown Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: multipart/alternative; boundary=Apple-Mail-9--959913054 Subject: Re: [LML] Re: Thermal influence on Hydraulic Pressure X-Original-Date: Wed, 30 Jan 2013 20:29:36 -0600 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1085) --Apple-Mail-9--959913054 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 Just went through that problem on my Legacy; VEP switch prevented = retraction; checked out perfectly on the ground, regularly malfunctioned = if flight. I polled the LML and got several great inputs; selected the = TCW ASW-1, available for $45 from Aircraft Spruce (vs $380 quote from = Lancair for the VEP). It's much smaller, lighter, easy to calibrate, = and so far, is working perfectly. On Jan 30, 2013, at 11:30 AM, Gary Edwards wrote: Rob, =20 Most likely the original VEP switches will be internally corroided and = not usuable if they have never been put into service. I went thru that = situation years ago (1990's) during the extended build time. It cost a = fortune to have the VEP company even just test them them, more than a = new set from Lancair would cost for the new style. And the new style is = install and fly, whereas the VEP's require adjustments during new flight = hours, a big inconvenience. =20 Gary Edwards LNC2=20 =20 From: Chris Zavatson To: lml@lancaironline.net Sent: Wednesday, January 30, 2013 5:28 AM Subject: [LML] Re: Thermal influence on Hydraulic Pressure Rob, Lancair carries a new type that is much more reliable. I forget the = brand name. =20 Chris Zavatson N91CZ 360std 1,400 hrs http://www.n91cz.net/ =20 From: Stevens Family To: lml@lancaironline.net=20 Sent: Tuesday, January 29, 2013 6:40 PM Subject: [LML] Re: Thermal influence on Hydraulic Pressure Chris, =20 I am interested in your comment about the =93Old VEP pressure switches=94.= The 360 kit I am building comes with those pressure switches. What do = you recommend we should use in place of them? =20 Thanks again. =20 Rob Stevens Perth, Western Australia. =20 =20 From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = Chris Zavatson Sent: Tuesday, 29 January 2013 11:56 PM To: lml@lancaironline.net Subject: [LML] Re: Thermal influence on Hydraulic Pressure =20 Scott, Yep, the failure modes are completely unrelated to each other. There is a second failure-to-retract mode. In fact, 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.=20 Failure to retract can be a bit more serious if in IMC or taking off at = high density altitude. =20 The failure to extend can be fixed by simply raising the operating = 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 measuring the spool resistance in every pump I get my hands = on. -haven't found an outliers yet, but I will keep looking. =20 Chris Zavatson N91CZ 360std 1,400hrs http://www.n91cz.net/ =20 From: "Sky2high@aol.com" To: lml@lancaironline.net=20 Sent: Tuesday, January 29, 2013 5:27 AM Subject: [LML] Re: Thermal influence on Hydraulic Pressure =20 Chris, =20 While waiting for Wolfgang's answer, some 200/300 series pilots are = becoming concerned that they can't get the gear down when needed. = First, Lorn's secondary problem is that he didn't look for the "gear = down and locked" lights before landing. While the gear down pressure = switch saw enough pressure to not allow the pump to start, the failure = to recognize that the gear was not down contributed to the belly in = landing. =20 To allow people to be more comfortable about the hydro-electric system = they should be reminded of this =20 1. The failure to RETRACT the gear because of high pressure on both = sides is a problem because of the safe design. Opening the dump valve = doesn't resolve the problem because the system is in a static state with = the gear down and locked. There are no physical forces able to change = the system condition - no G-maneuvers, no slips or skids, nada. =20 2. The failure to EXTEND the gear because of high pressure on both sides = is different. Opening the dump valve (allowing down side fluid to flow = to the upside) will allow the gear to "emergency" extend because of = gravity on the mains and the nose gear gas spring. OK, maybe the nose = gear might not extend all the way at 120 KIAS (max gear extension = speed), but the pressure lock has been broken and the pump will start if = the switch is down and the pump breaker is closed. Close the dump valve = to complete the process. As a matter of fact, assuming everything is = normal and the gear down switch is selected but nothing happens, it may = merely require momentarily cracking the dump valve to relieve the = hydraulic constipation. =20 Failing to retract is a nuisance. Failing to extend is, uh, more = serious, but resolvable. =20 Scott Krueger AKA Grayhawk =20 In a message dated 1/29/2013 6:54:27 A.M. Central Standard Time, = chris_zavatson@yahoo.com writes: Wolfgang, I seem to recall you dismissed the idea of a three-way valve previously. <> <<..........Automatic action by my module can prevent these problems for = both up and down gear operation. Wolfgang>> =20 Could you please explain how your module will prevent the gear extension = lock-up failures. Recall Lorn's photo after his extension failure and = gear up landing. Both pressure gauges showed around 500 psi. The = system is hydraulically locked with one switch open and one closed. =20 Chris Zavatson N91CZ 360std, 1,400 hrs http://www.n91cz.net/ =20 From: Wolfgang To: lml@lancaironline.net=20 Sent: Saturday, January 26, 2013 11:24 AM Subject: [LML] Re: Thermal influence on Hydraulic Pressure =20 This has been covered at great length before. Some take the position = that "real pilots" don't need anything but the dump valve. I have proposed two answers, 1) replace the dump valve that only opens a port between the HI and LO = sides with a dump valve that dumps back to the pump reservoir. 2) install a small electric module I make across the pressure switches = that runs the pump to relieve the over pressure in the "wrong" line = automatically. =20 Wolfgang ----- Original Message ----- From: Charles Brown To: lml@lancaironline.net Sent: Saturday, January 26, 2013 2:07 AM Subject: Re: [LML] Re: Thermal influence on Hydraulic Pressure =20 This has happened to me even at the beginning of a flight, if the temps = in the hangar have gone from cold on a previous day, to warm on flight = day. I guess cold 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 that the "up" and "down" pressure switches are = both open and the gear won't move until I pop the bleed valve. =20 Nasty when the gear won't retract just after blasting off into a low = overcast. =20 Charley Brown Legacy #299 200 hr =20 On Jan 25, 2013, at 7:23 AM, randy snarr wrote: =20 . I dont like having to open the dump valve but it is necessary once in = a while especially when it is cold. The pressures on both sides of the = system climb due to the engine heat and the gear sometimes will not move = without dumping the pressure. =20 =20 -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html =20 =20 -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html --Apple-Mail-9--959913054 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252
Rob,
 
Most likely the original VEP switches will be internally corroided = and not=20 usuable if they have never been put into service.  I went thru = that=20 situation years ago (1990's) during the extended build time.  It = cost a=20 fortune to have the VEP company even just test them them, more than a = new set=20 from Lancair would cost for the new style.  And the new style is = install=20 and fly, whereas the VEP's require adjustments during new flight hours, = a big=20 inconvenience.
 
Gary Edwards
LNC2 
 
Sent: Wednesday, January 30, = 2013 5:28=20 AM
Subject: [LML] Re: Thermal = influence on=20 Hydraulic Pressure

Rob,
Lancair carries a new type that is much more = reliable.  I=20 forget the brand name.
 
Chris Zavatson
N91CZ
360std 1,400 hrs

 
From:=20 Stevens Family <stevens5@swiftdsl.com.au><= br>To: lml@lancaironline.net =
Sent: Tuesday, = January 29, 2013 6:40=20 PM
Subject: [LML] = Re: Thermal=20 influence on Hydraulic Pressure

Chris,
 
I=20 am interested in your comment about the =93Old VEP pressure switches=94.= The 360=20 kit I am building comes with those pressure switches. What do you = recommend we=20 should use in place of them?
 
Thanks=20 again.
 
Rob=20 Stevens
Perth,
Western=20 Australia.
 
 
From:=20 Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = Chris=20 Zavatson
Sent: Tuesday, 29 January 2013 11:56 = PM
To:=20 lml@lancaironline.net
Subj= ect: [LML] Re: Thermal influence on=20 Hydraulic Pressure
 
Scott,
Yep, the = failure=20 modes are completely unrelated to each other.
There is a = second=20 failure-to-retract mode.  In fact, it is the only one I = experienced in my=20 plane.  It was with the old VEP pressure switches.  They = would stick=20 open on occassion.  Then the problem is not too much pressure, it = is not=20 having any. 
Failure to = retract=20 can be a bit more serious if in IMC or taking off at high density=20 altitude.
 
The failure = to extend=20 can be fixed by simply raising the operating pressure of the low side=20= circuit.
I have looked = at=20 pumps spanning the 95 to 2011 manufacturing time frame.  The only = one=20 that would lock up on the ground had spool return springs.  Since = the 70g=20 rattle-your-spool controversy appeared, I have also been measuring the = spool=20 resistance in every pump I get my hands on.  -haven't found = an=20 outliers yet, but I will keep looking.
 
Chris=20 Zavatson
N91CZ
360std=20 1,400hrs
http://www.n91cz.net/
 
From: "Sky2high@aol.com" <Sky2high@aol.com>
To:= lml@lancaironline.net=20
Sent: Tuesday, January 29, 2013 5:27 AM
Subject: = [LML]=20 Re: Thermal influence on Hydraulic Pressure
 
Chris,
 
While=20 waiting for Wolfgang's answer, some 200/300 series pilots are becoming=20= concerned that they can't get the gear down when needed.  First, = Lorn's=20 secondary problem is that he didn't look for the "gear down and = locked" lights=20 before landing.  While the gear down pressure switch saw = enough=20 pressure to not allow the pump to start, the failure to recognize = that=20 the gear was not down contributed to the belly in = landing.
 
To=20 allow people to be more comfortable about the hydro-electric system = they=20 should be reminded of this
 
1.=20 The failure to RETRACT the gear because of high pressure on both = sides is=20 a problem because of the safe design.  Opening the dump = valve=20 doesn't resolve the problem because the system is in a static = state with=20 the gear down and locked.  There are no physical forces able = to=20 change the system condition - no G-maneuvers, no slips or skids,=20 nada.
 
2.=20 The failure to EXTEND the gear because of high pressure on both sides = is=20 different.  Opening the dump valve (allowing down side fluid to = flow to=20 the upside) will allow the gear to "emergency" extend because of = gravity on=20 the mains and the nose gear gas spring.  OK, maybe the nose = gear=20 might not extend all the way at 120 KIAS (max gear extension speed), = but the=20 pressure lock has been broken and the pump will start if the switch is = down=20 and the pump breaker is closed.  Close the dump valve to complete = the=20 process.  As a matter of fact, assuming everything is normal and = the gear=20 down switch is selected but nothing happens, it may merely require = momentarily=20 cracking the dump valve to relieve the hydraulic=20 constipation.
 
Failing=20 to retract is a nuisance.  Failing to extend is, uh, more = serious, but=20 resolvable.
 
Scott=20 Krueger AKA Grayhawk
 
In a=20 message dated 1/29/2013 6:54:27 A.M. Central Standard Time, chris_zavatson@yahoo.com=20= writes:
Wolfgang,
I seem to recall=20 you dismissed the idea of a three-way valve previously.
<<That's a sound and positive = fix.
- - However it requires changing the = dump valve,=20 running a return line and pump modification (replace the=20 reservoir).
...................................
Wolfgang>>
<<..........Automatic = action by=20 my module can prevent these problems for both up and down gear=20 operation.
Wolfgang>>
 
Could you please=20 explain how your module will prevent the gear extension lock-up=20 failures.  Recall Lorn's photo after his extension failure and = gear up=20 landing.  Both pressure gauges showed around 500 psi.  The = system=20 is hydraulically locked with one switch open and one=20 closed.
 
Chris Zavatson
N91CZ
360std, 1,400 hrs
 
From:=20 Wolfgang <Wolfgang@MiCom.net>
To:= =20 lml@lancaironline.net=20
Sent: Saturday, January 26, 2013 11:24 = AM
Subject:=20 [LML] Re: Thermal influence on Hydraulic Pressure
 
This=20 has been covered at great length before. Some take the position that = "real=20 pilots" don't need anything but the dump valve.
I=20 have proposed two answers,
1)=20 replace the dump valve that only opens a port between the HI and LO = sides=20 with a dump valve that dumps back to the pump reservoir.
2)=20 install a small electric module I make across the pressure switches=20= that runs the pump to relieve the over pressure in the = "wrong"=20 line automatically.
 
Wolfgang
-----=20 Original Message -----
From:=20 Charles=20 Brown
Sent:=20 Saturday, January 26, 2013 2:07 AM
Subject:=20 Re: [LML] Re: Thermal influence on Hydraulic = Pressure
 
This has happened to me even at the = beginning of a=20 flight, if the temps in the hangar have gone from cold on a = previous day,=20 to warm on flight day.  I guess cold temps shrink the fluid = and suck=20 more from the reservoir into the lines, and when it warms, the = pressure=20 builds on both sides of the system, so that the "up" and "down" = pressure=20 switches are both open and the gear won't move until I pop the = bleed=20 valve.
 
Nasty when the gear won't retract = just after blasting=20 off into a low overcast.
 
Charley Brown
Legacy #299  200 = hr
 
On Jan 25, 2013, at 7:23 AM, randy = snarr=20 wrote:
 
. I dont like=20 having to open the dump valve but it is necessary once in a while=20= especially when it is cold. The pressures on both sides of the = system=20 climb due to the engine heat and the gear sometimes will not move = without=20 dumping the pressure.
 
 


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