X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 08 Sep 2012 18:22:17 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 6.0c1) with ESMTP id 5751037 for lml@lancaironline.net; Sat, 08 Sep 2012 12:14:37 -0400 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=Vb91zSV9 c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3Zlka_XeuxsA:10 a=ttCsPuSJ-FAA:10 a=rTjvlri0AAAA:8 a=yEMwTBQxYQMA:10 a=TI8fiyv6AAAA:8 a=Ia-xEzejAAAA:8 a=LdgTio7UAAAA:8 a=EscoftR0xbP_HTsI_sIA:9 a=pILNOxqGKmIA:10 a=5kvpSFHyPpYA:10 a=Ed44XO5Y-eEA:10 a=Dr9Wx-Q63l4A:10 a=EzXvWhQp4_cA:10 a=3FF-QIQ597OQuT8l:21 a=rqDzX7jQaqrIyvi5:21 a=5Up8faWwAAAA:8 a=g2ltN12PDr-SBZ1vHuIA:9 a=_W_S_7VecoQA:10 a=v6MMM96S_sUA:10 a=ZINqLuSsB2tZJ6vu:21 a=JhSQBaf0EN7tJg5_:21 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1865] helo=lobo) by hrndva-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id C5/6E-17584-5CE6B405; Sat, 08 Sep 2012 16:13:57 +0000 X-Original-Message-ID: <010001cd8ddc$f4126460$6701a8c0@lobo> From: "Wolfgang" X-Original-To: Subject: Fw: Accumulators X-Original-Date: Sat, 8 Sep 2012 12:13:58 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00FD_01CD8DBB.6CE1CAB0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_00FD_01CD8DBB.6CE1CAB0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Here is a copy of an email I sent 3 years ago with details you might be = interested in, =3D =3D =3D =3D =3D LNC2 landing gear hydraulic lock up problem. Type 1 = & Type 2=3D =3D =3D =3D =3D This problem has been lamented on for quite a while by my friend Lorn = Olsen and recently I finally got into the details involved. It appears that when the system is heat soaked, both sides end up at = pressures above the pressure switch settings and consequently the pump = can not run in either direction rendering the gear cycle inoperable. = This can happen after a long cruise at very low temperatures and a = descent to warmer conditions. The only thing left at that point is to = open the dump valve equalizing the HI and LO side pressures so gravity = and springs can lower the gear. Additionally, this could prevent gear = retraction after takeoff if the pressures are still high. The pump used is the OilDyne 108 series = http://www.parker.com/literature/Literature%20Files/euro_cylinder/v4/108_= 1301-uk.pdf - see pg 9 for internals. The Lancair part number is 6422666 and the OilDyne number is = 108AMS32-CZZ-3V-14-08 I have talked with the project manager of the 108 series at OilDyne and = found that the only non standard part is the ZZ which indicates a = modified LB circuit where the back pressure valve has been modified to = be bi-directional and it's restrictor has been removed. The check valves = are standard and still have a 1:5 actuation pressure ratio. Heat soak causes the hydraulic volume to increase noticeably increasing = the line pressure. This pressure will build up because the check valves = in the pump prevent any fluid flow back into the pump when there is no = power to the pump. There is a shuttle valve in the pump that opens the = non-action side check valve to open by pressure from the action side but = that pressure is from the pump side of the check valve. This shuttle = valve is spring loaded to center so without the pump running, neither = check valve is open. A heat soak of as little of 40 degrees can cause this problem. So, the fix is to prevent the non-action side pressure from increasing = above the pressure switch setting due to heat soak and / or bring it = down if it does. This can be accomplished in two ways. -------------------------------------------------------------------------= ------- 1 ) Electric only =3D =3D =3D Rewire the system so the pump will run = action side even though it's pressure switch is satisfied AND the = non-action side switch is also satisfied (and it shouldn't be). This = will build up pressure upstream (pump side) of the action side check = valve causing the shuttle to move off center and the non-action side = check valve to open releasing the non-action side pressure. I have designed a circuit board that has 4 relays that can be wired into = the system using the existing switches and wiring. The pressure = switches, gear switch and pump solenoids will be connected to it. It = will be about 3" x 4" x 1". If I get at least 5 requests, I will make a = batch of units for those interested. -------------------------------------------------------------------------= ------- 2 ) Hydraulic only =3D =3D =3D Add an accumulator to each HI and LO side = to absorb the temperature induced volume/pressure increase. I initially thought 5 cu.in. units (Parker # AD007B25T9A1) with a = precharge of about 100-200 psi would work even though they were larger = than needed. Upon further examination, I considered a length of flexible (expandable) = hose added to the system since that would be much easier to install. I = just needed to figure out the required length. After rounding up = expansion numbers from AeroQuip on their 303-5 and 303-8 hose and other = details; 303-5 ID=3D1/4" 303-5 hose expansion =3D 0.094cc / in at 1000 psi 303-5 hose expansion =3D 0.123cc / in at 2000 psi 303-5 hose expansion =3D 0.149cc / in at 3000 psi 303-8 ID =3D 13/32" 303-8 hose expansion =3D 0.100cc / in at 600 psi 303-8 hose expansion =3D 0.137cc / in at 1250 psi 303-8 hose expansion =3D 0.171cc / in at 2000 psi Hydraulic fluid volume in the LNC2 is about 27 cu in ; 6.4 cu in in the = lines, ; 20.6 cu in the actuators with door actuators Hydraulic fluid thermal expansion coefficient =3D .0005 / deg.F Aluminum thermal expansion coefficient =3D .0000123 / deg.F (negligible = for this purpose) Modulus of elasticity of hydraulic fluid =3D 250,000 (compression under = pressure - psi per percent reduction in volume - negligible for this = purpose) I calculated that about 8ft of 303-5 with AN4 fittings would provide the = desired volume expansion from heat soak.=20 Fluid in the non-action side of the system =3D 3.2 cu in. 8ft of 303-5 line =3D 4.71 cu in Fluid in the non-action side of the system with added line =3D 7.9 cu in = (ignoring volume of removed line segment) Extrapolated volume increase in the added line at 300 psi =3D 0.065cc / = in Volume increase =3D 0.065 / 2.54^3 x 96 =3D 0.381 cu in Delta T allowance =3D 0.381 / (7.9 x 0.0005) =3D 96.5 degF with 300 psi = increase Replace an existing piece of line with a 3 loop coil under each seat = pan, one plumbed into the HI side and the other plumbed into the LO side = and bleed the system. There are other details but these are the basics. These are initial calculations and have not yet been tested. -------------------------------------------------------------------------= ------- CAUTION If there is a leak in a cylinder or the dump valve, there will still be = a problem that can render the gear inoperative leaving only emergency = dump valve use. The action side can leak into the non-action side, the pump will turn on = to bring the action side pressure back up, the leak will continue untill = both sides are above the pressure switch setting. Should heat soak come = into play after that, the pressures can continue up to 1500 psi, the = thermostatic relief valve setting of the pump. The first proposed electrical only solution can overcome the leak = problem but is a bit more involved installation. If anyone wants more details, feel free to email me Wolfgang@MiCom.net Wolfgang Franke ----- Original Message -----=20 From: Jim Nordin=20 To: lml@lancaironline.net=20 Sent: Friday, September 07, 2012 8:10 AM Subject: Accumulators I want to employ an accumulator after reading all about the problems. = So I figured someone would know what size to use on the wee little 320 = hydraulic system.=20 I went to the internet to see if there was a formula for doing such. = And there is: http://www.accumulators.com/sizing.html=20 Of course somebody must know the volume in the system. Does anybody = know that? My guess is between .15 gallons and .2 gallons (19-25 = ounces). If this is close the accumulator of 3-7 in3 might be close too. The temperature ranges are 10=BAF to 160=BAF (too high I=92m sure). = Max pressure 2,000psi initial of 500psi. If the initial pressure is = 1,000psi or so, the vol of the accumulator rises to about 10 in3.=20 Can somebody help please? Comments? Jim ------=_NextPart_000_00FD_01CD8DBB.6CE1CAB0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
Here is a copy of an email I = sent 3 years=20 ago with details you might be interested in,
 
=3D =3D =3D =3D =3D LNC2 landing gear hydraulic lock = up problem. Type 1=20 & Type 2=3D =3D =3D =3D =3D
 
This problem has been lamented on for quite a while = by my=20 friend Lorn Olsen and recently I finally got into the details=20 involved.
 
It appears that when the system is heat soaked, both = sides end=20 up at pressures above the pressure switch settings and consequently the = pump can=20 not run in either direction rendering the gear cycle inoperable. This = can happen=20 after a long cruise at very low temperatures and a descent to warmer = conditions.=20 The only thing left at that point is to open the dump valve equalizing = the HI=20 and LO side pressures so gravity and springs can lower the gear. = Additionally,=20 this could prevent gear retraction after takeoff if the pressures are = still=20 high.
 
The pump used is the OilDyne 108 series http://www.parker.com/literature/Literature%20Files/= euro_cylinder/v4/108_1301-uk.pdf -=20 see pg 9 for internals.
The Lancair part number is 6422666 and the OilDyne = number is=20 108AMS32-CZZ-3V-14-08
 
I have talked with the project manager of the 108 = series at=20 OilDyne and found that the only non standard = part is=20 the ZZ which indicates a modified LB circuit where the back = pressure valve=20 has been modified to be bi-directional and it's restrictor has been = removed. The=20 check valves are standard and still have a 1:5 actuation pressure=20 ratio.
 
Heat soak causes the hydraulic volume to increase = noticeably=20 increasing the line pressure. This pressure will build up because the = check=20 valves in the pump prevent any fluid flow back into the pump when there = is no=20 power to the pump. There is a shuttle valve in the pump that opens the=20 non-action side check valve to open by pressure from the action side but = that pressure is from the pump side of the check valve. This = shuttle=20 valve is spring loaded to center so without the pump running, neither = check=20 valve is open.
 
A heat soak of as little of 40 degrees can cause = this=20 problem.
 
So, the fix is to prevent the non-action side = pressure from=20 increasing above the pressure switch setting due to heat soak and / or = bring it=20 down if it does.
 
This can be accomplished in two ways.
1 ) Electric only =3D =3D =3D Rewire the system so = the pump will run=20 action side even though it's pressure switch is satisfied AND the=20 non-action side switch is also satisfied (and it shouldn't be). This = will build=20 up pressure  upstream (pump side) of the action side check valve = causing=20 the shuttle to move off center and the non-action side check valve to=20 open releasing the non-action side pressure.
 
I have designed a circuit board that has 4 relays = that can be=20 wired into the system using the existing switches and wiring. The = pressure=20 switches, gear switch and pump solenoids will be connected to it. It = will be=20 about 3" x 4" x 1". If I get at least 5 requests, I will make a batch of = units=20 for those interested.
2 ) Hydraulic only =3D =3D =3D Add an accumulator to = each HI and LO=20 side to absorb the temperature induced volume/pressure = increase.
 
I initially thought 5 cu.in. units (Parker #=20 AD007B25T9A1) with a precharge of about 100-200 psi would work even = though they=20 were larger than needed.
 
Upon further examination, I considered a length of = flexible=20 (expandable) hose added to the system since that would be much easier to = install. I just needed to figure out the required length.=20 After rounding up expansion numbers from AeroQuip on their 303-5 = and 303-8=20 hose and other details;
 
303-5 ID=3D1/4"
303-5 hose expansion =3D 0.094cc / in at 1000=20 psi
303-5 hose expansion =3D 0.123cc / in at 2000=20 psi
303-5 hose expansion =3D 0.149cc / in at 3000=20 psi
 
303-8 ID =3D 13/32"
303-8 hose expansion =3D 0.100cc / in = at 600=20 psi
303-8 hose expansion =3D 0.137cc / in at 1250=20 psi
303-8 hose expansion =3D 0.171cc / in at 2000=20 psi
 
Hydraulic fluid volume in the LNC2 is about 27 cu=20 in ;  6.4 cu in in the=20 lines, ; 20.6 cu in the actuators with = door=20 actuators
Hydraulic fluid thermal expansion = coefficient =3D .0005 /=20 deg.F
Aluminum thermal expansion coefficient =3D = .0000123 / deg.F=20 (negligible for this purpose)
Modulus of elasticity of hydraulic fluid =3D = 250,000=20 (compression under pressure - psi per percent reduction in = volume -=20 negligible for this purpose)
 
I calculated that about 8ft of 303-5 with = AN4 fittings=20 would provide the desired volume expansion from heat soak.
 
Fluid in the non-action side of the system =3D = 3.2 cu=20 in.
8ft of 303-5 line =3D 4.71 cu in
Fluid in the non-action side of the system with = added=20 line =3D 7.9 cu in (ignoring volume of removed line = segment)
Extrapolated volume increase in the added line at = 300=20 psi =3D 0.065cc / in
Volume increase =3D 0.065 / 2.54^3 x 96 =3D = 0.381 cu=20 in
Delta T allowance =3D 0.381 / (7.9 x 0.0005) =3D = 96.5 degF with=20 300 psi increase
 
Replace an existing piece of line with a 3 loop = coil=20 under each seat pan, one plumbed into the HI side and the other plumbed = into the=20 LO side and bleed the system.
 
There are other details but these are the = basics.
These are initial calculations and have not yet been = tested.
CAUTION
If there is a leak in a cylinder or the dump valve, = there will=20 still be a problem that can render the gear inoperative leaving=20 only emergency dump valve use.
The action side can leak into the = non-action side,=20 the pump will turn on to bring the action side pressure back up, the = leak will=20 continue untill both sides are above the pressure switch setting. Should = heat=20 soak come into play after that, the pressures can continue up to = 1500 psi,=20 the thermostatic relief valve setting of the pump.
 
The first proposed electrical only solution can = overcome=20 the leak problem but is a bit more involved = installation.
 
If anyone wants more details, feel free to email me = Wolfgang@MiCom.net
 
Wolfgang Franke
 
----- Original Message -----
From:=20 Jim=20 Nordin
Sent: Friday, September 07, = 2012 8:10=20 AM
Subject: Accumulators

I want to employ an accumulator after = reading all=20 about the problems. So I figured someone would know what size to use = on the=20 wee little 320 hydraulic system.
I went to the internet to see if = there=20 was a formula for doing such. And there is:

 

http://www.accumulators.= com/sizing.html=20

 

Of course somebody must know the volume in = the system.=20 Does anybody know that? My guess is between .15 gallons and .2 gallons = (19-25=20 ounces). If this is close the accumulator of 3-7 in3 might be close=20 too.

The temperature ranges are 10=BAF to 160=BAF = (too high I=92m=20 sure). Max pressure 2,000psi initial of 500psi. If the initial = pressure is=20 1,000psi or so, the vol of the accumulator rises to about 10 = in3.

Can somebody help please? = Comments?

Jim

 

------=_NextPart_000_00FD_01CD8DBB.6CE1CAB0--