X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 16 Feb 2013 22:21:05 -0500 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 6.0.1) with ESMTP id 6067330 for lml@lancaironline.net; Sat, 16 Feb 2013 12:10:34 -0500 Received-SPF: none receiver=logan.com; client-ip=71.74.56.122; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=2.0 cv=UN5f7Vjy c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3Zlka_XeuxsA:10 a=lk4ivj3xPSEA:10 a=ttCsPuSJ-FAA:10 a=rTjvlri0AAAA:8 a=GXDs6gbc4P8A:10 a=Ia-xEzejAAAA:8 a=5FIZSGrRAAAA:8 a=ndVRne3UAAAA:8 a=CjxXgO3LAAAA:8 a=KNfte85PAAAA:8 a=AuDK7gFjkmzlUzrGkfAA:9 a=QEXdDO2ut3YA:10 a=wR8WdYEwGqoA:10 a=ILeVjEvywfEA:10 a=EzXvWhQp4_cA:10 a=Dr9Wx-Q63l4A:10 a=rC2wZJ5BpNYA:10 a=8m6LRutVOowA:10 a=zymdntL9rU6DcFKi:21 a=0aATGowvNUNhtOep:21 a=ya_rp_WfFSY9TYGJLEEA:9 a=tXsnliwV7b4A:10 a=eFW6tJeE8hw7wwC3:21 a=etcM5ahpXh3W3Xkb:21 a=aHVcYm0VEiXjgSdY:21 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1136] helo=lobo) by hrndva-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 51/07-20480-66DBF115; Sat, 16 Feb 2013 17:09:59 +0000 X-Original-Message-ID: <64053169227C419E964E291DEE164A4D@lobo> From: "Wolfgang" X-Original-To: References: Subject: Re: [LML] Re: Fw: [LML] Re: Thermal influence on Hydraulic Pressure X-Original-Date: Sat, 16 Feb 2013 12:09:51 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0050_01CE0C3E.8601BE90" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5512 This is a multi-part message in MIME format. ------=_NextPart_000_0050_01CE0C3E.8601BE90 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Chris, Ok, let's agree to disagree.=20 You want to take a plane down for a couple of weeks while you tear down = the pump. I don't need a pump sent to me for tear down and modification. = My module is a 20 minute add-on that will mitigate the problem for both = up and down function . . . without getting particular with the pressure = settings. The only down side (as with any other part of the airframe) is = if you failed to build your hydraulic system to spec. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Friday, February 15, 2013 4:04 PM Subject: Re: [LML] Re: Fw: [LML] Re: Thermal influence on Hydraulic = Pressure Wolfgng, =E2=80=9CHow do some spools come off their endpoints and cause = reported failure?=E2=80=9D =20 That question was answered long ago. I can show you how to rig a pump = to lock up and then I can show you how to rig it such that it = can=E2=80=99t lock up. =20 Developing a fix for a problem before understanding the root cause is = not a smart way to go about things. You saw an issue on one airplane. = Unfortunately you refused to pull the pump to look at it, simply telling = us that the pump was too difficult to reach. That is a really poor = excuse. Yes, the pump was behind the baggage bulkhead and it is not = easy to get to it. How can that be a valid reason for not examining the = actual hardware? Initially it was claimed this module would solve lock-up in both = directions. Reading through the description of its theory of operation, = it is clear the module cannot catch the =E2=80=98failure to = extend=E2=80=99 lock-up. A system state was missed.=20 There are downsides to having to use the pump to forcibly unlock a = thermally locked system. I am sure you are aware of those. I am = curious what new failure modes have been introduced if any one part of = the module fails? I offered to look at Lorn=E2=80=99s pump as I have done for others. = Your reply was that a week or two of down time was too much of a price = to pay. Really! I am still in search of a pump that falls outside the expected = behavior when configured properly. I would truly like to find one as it = can only serve to further our understanding of our planes. What a shame = and loss to the community if you (or really Lorn) truly possess such a = pump. I know, I know, it is too much effort to pull the pump. Please don=E2=80=99t extrapolate the behavior of the one pump you saw = only from the outside to the rest of the fleet.=20 Disclaimer: I don=E2=80=99t have a financial interest in this = discussion=E2=80=A6=E2=80=A6.well maybe I do. I am trying to keep our = insurance rates from going up. For your entertainment I have attached some photos of my pressure = gauges after my plane was exposed to thermal soak, both in the air and = on the ground. You will see that only the commanded side is affected by = thermal influence. And here are some video clips: The first video shows how a pump with spool return springs can lock up = when subjected to rising temperatures. The second clip shows a pump = without return springs. Only the currently active side is affected by = temperature changes. No lock-up Hydraulic Lock due to thermal cycling (=E2=80=9CCZZ=E2=80=9D = configured pump with spool return springs installed) Normal Pump operation when subjected to thermal = cycling.(=E2=80=9CLB=E2=80=9D) configured pump without return springs 320/360 Hydraulics Tutorial Chris Zavatson N91CZ L360std 1,400 hrs (lock-up free) www.N91CZ.net From: Wolfgang To: lml@lancaironline.net=20 Sent: Thursday, February 14, 2013 11:48 AM Subject: [LML] Re: Fw: [LML] Re: Thermal influence on Hydraulic = Pressure What did you measure to come up with that 70 g's ? and . . . the springs trying to center the spool in some models = certainly don't help. So the question still lingers from more than a year ago,=20 How do some spools come off their end position and cause the reported = failures ? That's why I came up with the module I have.=20 It powers the spool back into position whenever needed, regardless of = pump model. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Wednesday, February 13, 2013 7:55 AM Subject: Re: [LML] Fw: [LML] Re: Thermal influence on Hydraulic = Pressure Reposted from June 2011 = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D ----- 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 = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D From: Wolfgang To: lml@lancaironline.net=20 Sent: Monday, February 11, 2013 12:36 PM Subject: [LML] Fw: [LML] Re: Thermal influence on Hydraulic Pressure 70 g's is an impressive number. How was that measured ?=20 Or is that just a measure of the vibration that the part lives under = during flight ? Wolfgang From: Chris Zavatson To: lml@lancaironline.net=20 Sent: Saturday, January 26, 2013 12:24 PM Subject: [LML] Re: Thermal influence on Hydraulic Pressure Randy, Thanks. =20 There are two things I have been doing to pumps to eliminate the = need for 'dump valve rescues'. =20 First is the removal of the return springs that entered the Legacy = pump design in about 2005. They added no useful functionality and = unfortunately introduced a lock-up failure mode. Removing the springs = primarily addresses lock-up on the ground during thermal swings. The second thing I have been doing is to set the low pressure switch = to 800-850 psi. This eliminates the gear extension lock-up mode that = occasionally prevents the gear from fully extending. The original = setting was to low to overcome the pressure spike that propagates = through the system when the gear first come out of the wheel wells. The other thing I have been doing is measuring the spool = resistance on every pump that comes across my desk. I haven't found any = issues there. 70g's is the typical result. I have also been making thermal relief valves adjustable, bringing = the set-point into a usable range (2,000 psi) for our systems. The three-way dump valve references in that write-up were merely = describing the Legacy hydraulic system. The Legacy cannot perform a = gear free-fall extension without a three way valve due to cylinder = orientation. I still use a two-way valve in my 360. Chris Chris Zavatson N91CZ 360std 1,400 hrs http://www.n91cz.net/ From: randy snarr To: lml@lancaironline.net=20 Sent: Friday, January 25, 2013 5:23 AM Subject: [LML] Re: Thermal influence on Hydraulic Pressure Nice Work Chris.. I am happy to hear that I have already done what you suggested which = is to install a 3 way dump valve and run the dump line to the reservoir = in a low pressure line. It has worked very well. 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. Have you found a solution for this with your research that makes the = original system function without having to ever dump the pressure = manually? Randy Snarr 235/320 N694RS=20 "Flight by machines heavier than air is unpractical and = insignificant, if not utterly impossible" -Simon Newcomb, 1902 From: Chris Zavatson To: lml@lancaironline.net=20 Sent: Tuesday, September 4, 2012 2:18 PM Subject: [LML] Re: Thermal influence on Hydraulic Pressure Danny, No affect on gear movement. I should add however that elevated high-side pressure is one of the = contributing factors to gear extension failures in a standard system set = up. My low pressure setting is higher than the nominal 550 psi. It is = set to 800 psi to avoid the pressure spike that propogates through the = system when gear down is selected. see "Failure to Extend" on page 10 for more detail. http://www.n91cz.com/Hydraulics/Lancair%20Hydraulics.pdf Chris Zavatson N91CZ 360std http://www.n91cz.net/=20 From: Danny To: lml@lancaironline.net=20 Sent: Monday, September 3, 2012 11:54 AM Subject: [LML] Re: Thermal influence on Hydraulic Pressure Chris, What was the impact on the gear movement? Danny LNC2-360 N 38=C2=B0 43' 25.7" W 77=C2=B0 30' 38.6" From: Chris Zavatson [mailto:chris_zavatson@yahoo.com]=20 Sent: Saturday, September 01, 2012 11:32 PM To: lml@lancaironline.net Subject: [LML] Thermal influence on Hydraulic Pressure -took this photo after a descent from 16.5k to 1,500 ft. OAT went from 42 to 94 degrees. High Pressure gauge is pegged at 2,000+ psi -Didn't get a photo, but the opposite happened on the ramp in = Spokane. After sitting for an hour, the low pressure gauge was pegged at = 1,200 psi+. Spokane might not be the warmest spot in the country, but = at 85 deg F, it was 55 degrees warmer than the cold soak on the previous = leg. Temperature changes have a big impact on system pressure.=20 Chris Zavatson N91CZ 360std http://www.n91cz.net/ =20 ------=_NextPart_000_0050_01CE0C3E.8601BE90 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Chris,
 
Ok, let's agree to disagree.
 
You want to take a plane down for a couple of = weeks while=20 you tear down the pump. I don't need a pump sent to me for tear = down and=20 modification. My module is a 20 minute add-on that will mitigate the = problem for=20 both up and down function . . . without getting particular with the = pressure=20 settings. The only down side (as with any other part of the airframe) is = if you=20 failed to build your hydraulic system to spec.
 
Wolfgang
 
----- Original Message -----
From:=20 Chris=20 Zavatson
Sent: Friday, February 15, 2013 = 4:04=20 PM
Subject: Re: [LML] Re: Fw: = [LML] Re:=20 Thermal influence on Hydraulic Pressure

Wolfgng,
=E2=80=9CHow do=20 some spools come off their endpoints and cause reported = failure?=E2=80=9D 
That=20 question was answered long ago.  I=20 can show you how to rig a pump to lock up and then I can show you how = to rig=20 it such that it can=E2=80=99t lock up. =20
Developing a fix for a problem before understanding the = root=20 cause is not a smart way to go about things.  You saw an issue on one = airplane.=20 Unfortunately you refused to pull the pump to look at it, simply = telling us=20 that the pump was too difficult to reach. That is a really poor = excuse.  Yes, the pump was behind the = baggage=20 bulkhead and it is not easy to get to it.  How can that be a valid = reason for not=20 examining the actual hardware?
Initially=20 it was claimed this module would solve lock-up in both = directions.  Reading through the = description of its=20 theory of operation, it is clear the module cannot catch the = =E2=80=98failure to=20 extend=E2=80=99 lock-up.  = A system state=20 was missed.
There are=20 downsides to having to use the pump to forcibly unlock a thermally = locked=20 system.  I am sure you = are aware=20 of those.  I am curious = what new=20 failure modes have been introduced if any one part of the module=20 fails?
I offered=20 to look at Lorn=E2=80=99s pump as I have done for others.  Your reply was that a week = or two of=20 down time was too much of a price to pay.  Really!
I am=20 still in search of a pump that falls outside the expected behavior = when=20 configured properly.  I = would=20 truly like to find one as it can only serve to further our = understanding of=20 our planes.  What a = shame and loss=20 to the community if you (or really Lorn) truly possess such a = pump.  I know, I know, it is too = much effort=20 to pull the pump.
Please=20 don=E2=80=99t extrapolate the behavior of the one pump you saw only = from the outside=20 to the rest of the fleet.
Disclaimer:  = I don=E2=80=99t=20 have a financial interest in this discussion=E2=80=A6=E2=80=A6.well = maybe I do.  I am trying to keep our = insurance=20 rates from going up.
For your=20 entertainment I have attached some photos of my pressure gauges after = my plane=20 was exposed to thermal soak, both in the air and on the ground.  You will see that only the = commanded=20 side is affected by thermal influence.
And here=20 are some video clips:
The first=20 video shows how a pump with spool return springs can lock up when = subjected to=20 rising temperatures.  = The second=20 clip shows a pump without return springs.  Only the currently active = side is=20 affected by temperature changes. =20 No lock-up
Hydraulic Lock due to thermal cycling (=E2=80=9CCZZ=E2=80=9D configured pump with spool = return springs=20 installed)
Normal Pump operation when subjected to thermal=20 cycling.(=E2=80=9CLB=E2=80=9D) = configured pump without return=20 springs
320/360 Hydraulics Tutorial
Chris=20 Zavatson
N91CZ
L360std=20 1,400 hrs (lock-up free)
www.N91CZ.net

From: Wolfgang=20 <Wolfgang@MiCom.net>
To: lml@lancaironline.net =
Sent: Thursday, February 14, = 2013 11:48=20 AM
Subject: [LML] = Re: Fw:=20 [LML] Re: Thermal influence on Hydraulic Pressure

What did you measure to come up with = that 70 g's=20 ?
and . . . the springs trying to = center the spool=20 in some models certainly don't help.
 
So the question still lingers from = more than a=20 year ago,
How do some spools come off their end = position=20 and cause the reported failures ?
 
That's why I came up with the module = I have.=20
It powers the spool back into = position whenever=20 needed, regardless of pump model.
 
Wolfgang
 
-----=20 Original Message -----
From:=20 Chris=20 Zavatson
To:=20 lml@lancaironline.net = Sent:=20 Wednesday, February 13, 2013 7:55 AM Subject:=20 Re: [LML] Fw: [LML] Re: Thermal influence on Hydraulic = Pressure

Reposted from June 2011
=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
-----=20 Original Message ----- From:=20 Chris Zavatson To:=20 lml@lancaironline.net Sent:=20 Saturday, June 25, 2011 12:35 PM Subject:=20 Re: [LML] Re: LNC2 Gear Hydraulics

Curiosity got the best of me. Here are the peak vibration = values=20 recorded today at the hydraulic pump measured on the axis = of the=20 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=20 any other component on the = plane.
Chris Zavatson
N91CZ
360std
= =

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
From: Wolfgang=20 <Wolfgang@MiCom.net>
To: lml@lancaironline.net =
Sent: Monday, February 11, = 2013 12:36=20 PM
Subject: [LML] = Fw: [LML]=20 Re: Thermal influence on Hydraulic Pressure

70 g's is an impressive number. How = was that=20 measured ?
Or is that just a measure of = the vibration=20 that the part lives under during flight ?
 
Wolfgang
 
 
From: Chris Zavatson=20 <chris_zavatson@yahoo.com>
To: lml@lancaironline.net =
Sent: Saturday, January 26, = 2013 12:24=20 PM
Subject: [LML] = Re:=20 Thermal influence on Hydraulic Pressure

Randy,
Thanks. 
    There=20 are two things I have been doing to pumps to eliminate the need for = 'dump=20 valve rescues'. 
First is the removal of the return springs that entered = the=20 Legacy pump design in about 2005.  They added no=20 useful functionality and unfortunately introduced a = lock-up=20 failure mode.  Removing the springs primarily addresses lock-up = on the=20 ground during thermal swings.
The second thing I have been doing is to set the low = pressure=20 switch to 800-850 psi.  This eliminates the gear extension = lock-up mode=20 that occasionally=20 prevents the gear from fully extending.  The original setting = was to=20 low to overcome the pressure spike that propagates through = the system=20 when the gear first come out of the wheel wells.
    The=20 other thing I have been doing is measuring the spool resistance = on=20 every pump that comes across my desk.  I haven't found any = issues=20 there.  70g's is the typical = result.
I have also been making thermal relief valves adjustable, = bringing the set-point into a usable range (2,000 psi) for our=20 systems.
 
    The=20 three-way dump valve references in that write-up were merely=20 describing the Legacy hydraulic system.  The Legacy = cannot=20 perform a gear free-fall extension without a three way = valve due=20 to cylinder orientation.  I still use a two-way valve in = my=20 360.
Chris
 
Chris Zavatson
N91CZ
360std 1,400 hrs
http://www.n91cz.net/
 

From: randy snarr=20 <randylsnarr@yahoo.com>
To: lml@lancaironline.net =
Sent: Friday, January 25, = 2013 5:23=20 AM
Subject: [LML] = Re:=20 Thermal influence on Hydraulic Pressure

Nice Work Chris..
I=20 am happy to hear that I have already done what you suggested which = is to=20 install a 3 way dump valve and run the dump line to the reservoir in = a low=20 pressure line. It has worked very well. I dont like having to open the dump = valve but it=20 is necessary once in a while especially when it is cold. The = pressures on=20 both sides of the system climb due to the engine heat and the gear = sometimes=20 will not move without dumping the pressure.
Have you=20 found a solution for this with your research that makes the original = system=20 function without having to ever dump the pressure manually?

Randy=20 Snarr
235/320
N694RS 
 
"Flight by machines heavier = than air=20 is unpractical and insignificant, if not utterly=20 impossible"
-Simon Newcomb, 1902
From: Chris Zavatson=20 <chris_zavatson@yahoo.com>
To: lml@lancaironline.net =
Sent: Tuesday, September 4, = 2012 2:18=20 PM
Subject: [LML] = Re:=20 Thermal influence on Hydraulic Pressure

Danny,
No affect on gear=20 movement.
I should add however = that=20 elevated high-side pressure is one of the contributing factors to = gear=20 extension failures in a standard system set up.  My low pressure = setting is=20 higher than the nominal 550 psi.  It is set to 800 psi to = avoid=20 the pressure spike that propogates through the system when gear down = is=20 selected.
see "Failure to = Extend" on=20 page 10 for more detail.
http://www.n91cz.com/Hydr= aulics/Lancair%20Hydraulics.pdf
  Chris=20 Zavatson N91CZ 360std http://www.n91cz.net/   

From: Danny=20 <danny@n107sd.com>
To: lml@lancaironline.net =
Sent: Monday, September 3, = 2012 11:54=20 AM
Subject: [LML] = Re:=20 Thermal influence on Hydraulic Pressure

Chris,
What was the impact = on the=20 gear movement?
 
Danny
LNC2-360
N 38=C2=B0 43'=20 25.7"
W 77=C2=B0 30'=20 38.6"
 
From: Chris = Zavatson=20 [mailto:chris_zavatson@yahoo.com]
Sent: Saturday, September 01, = 2012=20 11:32 PM
To:=20 lml@lancaironline.net
Subject: [LML] Thermal = influence on=20 Hydraulic Pressure
 
-took=20 this photo after a descent from 16.5k to 1,500=20 ft.
OAT went=20 from 42 to 94 degrees.
High=20 Pressure gauge is pegged at 2,000+ psi
-Didn't=20 get a photo, but the opposite happened on the ramp in = Spokane. After=20 sitting for an hour, the low pressure gauge was pegged at 1,200 = psi+. =20 Spokane might not be the warmest spot in the country, but at 85 deg = F, it=20 was 55 degrees warmer than the cold soak on the previous=20 leg.
Temperature=20 changes have a big impact on system=20 pressure. 
 
Chris=20 Zavatson
N91CZ
360std
http://www.n91cz.net/






 =20 =





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