X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 12 Mar 2012 07:56:10 -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 5.4.4) with ESMTP id 5436607 for lml@lancaironline.net; Sat, 10 Mar 2012 12:50:32 -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=M9vP2lMs c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3Zlka_XeuxsA:10 a=DTcCN-Bu46AA:10 a=ttCsPuSJ-FAA:10 a=Ia-xEzejAAAA:8 a=ndVRne3UAAAA:8 a=5FIZSGrRAAAA:8 a=rTjvlri0AAAA:8 a=bt6iiOTnXXtNZFXFm08A:9 a=4W52oJjDFlwKPAh-K_YA:7 a=QEXdDO2ut3YA:10 a=wR8WdYEwGqoA:10 a=EzXvWhQp4_cA:10 a=Dr9Wx-Q63l4A:10 a=CjxXgO3LAAAA:8 a=P3NBXBOXrj4360CWCTUA:9 a=bv3kewQYt0oo4D4Ybn4A:7 a=tXsnliwV7b4A:10 a=rC2wZJ5BpNYA:10 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1091] helo=lobo) by hrndva-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 8A/5A-05889-4449B5F4; Sat, 10 Mar 2012 17:49:56 +0000 X-Original-Message-ID: <004201ccfee6$328ce750$6701a8c0@lobo> From: "Wolfgang" X-Original-To: References: Subject: Re: [LML] Re: 320/360 Hydraulic Pressure Switch X-Original-Date: Sat, 10 Mar 2012 12:49:52 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_003F_01CCFEBC.498288E0" 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_003F_01CCFEBC.498288E0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Chris, You refer to a CZZ configuration but I don't find any such CZZ reference = in the Oildyne spec sheet. Can you elaborate ? Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Friday, March 09, 2012 11:06 AM Subject: Re: [LML] Re: 320/360 Hydraulic Pressure Switch=20 This first video shows the stock LB configuration operating normally = while going through multiple extreme thermal cycles both retracted and = extended. Note that the non-pressurized side remains at zero pressure = throughout the entire test. The pump responds, hot or cold, retracted = or extended. http://www.n91cz.com/Hydraulics/Thermal%20Cycling%20IIII.wmv This second video shows the CZZ configuration used on the Legacy which = adds return springs to the LB spool (actually LD, in this case) and = removes the back pressure feed in the return line. This configuration = is not compatible with the 320/360 hydraulic system. As shown in the = video, this configuration locks up. Note that the both high and low = sides rise and fall with temperature. Once the pressure rises above the = pressure switch set points, the pump cannot be engaged. =20 http://www.n91cz.com/Hydraulics/NewPumpLockUp_0001.wmv Reverting the CZZ configuration back to the 320/360 configuration took = about 10 minutes. http://www.n91cz.com/Hydraulics/Pump-Unlock.pdf Once the 320/360 pump configuration incorporated the LB back pressure = circuit, it became an incredibly reliable and trouble free part of the = aircraft design. It has tens, perhaps, hundreds of thousands of hours = of trouble free service. I gladly contributed 1,350 of those hours. I am not advocating any =E2=80=98fix=E2=80=99 and certainly not any = modification. Quite the contrary, I have never found the stock LB = configuration to need a fix. I do advocate ensuring the proper = configuration and proper adjustments are maintained. =20 Over the years, I have helped many Lancair owners resolve hydraulic = issues. I have found assembly errors (reversed spool valve), bad = poppet valves, pressure switch issues, both adjustment errors and = failures, faulty relays, hydraulic cylinder issues, even leaking dump = valves. Not once was the problem tied to the pump design. =20 I think it is a matter of maintenance philosophy. Chris Zavatson N91CZ 360std www.N91CZ.net From: Wolfgang To: lml@lancaironline.net=20 Sent: Tuesday, March 6, 2012 11:02 AM Subject: [LML] Re: 320/360 Hydraulic Pressure Switch=20 =EF=BB=BF=20 It's a matter of cost effectiveness. I'm still waiting for positive = evidence of what exactly is causing the failure so your fix can be = validated.=20 Again, I have come up with a fix that WILL fix that problem . . . for = less than what it costs to "fix" the pump, not to mention down time . . = . assuming that springs and vibration is what's causing the problem. But = you have said that vibration can't do that ? ? Your "fix" could be the answer but there is no way to know for sure = what is inside a particular pump without a dissection because part = numbers are not reliable. I'm thinking the springs are the culprit but that needs to be = demonstrated. The springs with the help of vibration are the only thing = that I can think of that can move the spindle off it's end position = against O-ring friction. I'm thinking that no springs and maybe harder = O-rings could be the answer. That scenario makes sense to me. You have the test rig you made up so why don't you simulate the = supposed problem and implement the supposed fix and document for all = what the "correct" answer is ?=20 Let us know if your approach WILL fix the problem. I have already done that with my electric module. Assuming the pump modification is a valid fix, which is more cost effective, remove, dissect, re-assemble, replace = the pump=20 or simply add the electric module using it's push-on connectors ? Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Monday, March 05, 2012 8:21 AM Subject: Re: [LML] Re: 320/360 Hydraulic Pressure Switch=20 Wolfgang, If a mechanic were to install a new cylinder on my plane using = incorrect rings that subsequently led to oil consumption of 2 qt/hr, I = could theoretically design a system that refills the sump to assure I = don=E2=80=99t run out of oil during long flights. The more customary = approach would be to remove the cylinder and install the correct rings. The =E2=80=98problem=E2=80=99 here is not that oil needs to be = replenished. The problem is the installation of incorrect parts. The = =E2=80=98fix=E2=80=99 is not to add a system to keep the sump = replenished. The fix is to use the correct rings. Chris Zavatson N91CZ 360std www.N91CZ.net=20 From: Wolfgang To: lml@lancaironline.net=20 Sent: Saturday, March 3, 2012 4:01 PM Subject: [LML] Re: 320/360 Hydraulic Pressure Switch=20 =EF=BB=BF=20 Chris, Life is complicated enough so when I fly, I like to enjoy it. Being = a slave to the system like a cog in a flying machine is not my idea of = "enjoyment". Don't get me wrong, I like getting into technicals up to my = eyebrows, but I prefer to do that at my choosing, not while tending to a = malfunction in flight. That's why I cane up with the gear module.=20 After you detailed the presence of springs in the pump to help = center the spool and popets, I see that my original supposition that the = spool is coming off it's end position is confirmed. It looks like the = springs are in fact, capable of overcoming the friction of the O-rings. = You keep measuring the forces in G's but that does not give us an actual = force measurement that is what the springs are operating against.=20 It remains that some pump installations have the problem of the = spool not maintaining the required position for safe flight operations. = You have come up with many details that go toward esplaining the problem = and a possible fix (take out the springs). I have come up with a module = that WILL fix that problem. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Friday, March 02, 2012 7:54 AM Subject: [LML] Re: 320/360 Hydraulic Pressure Switch=20 Wolfgang,=20 It is a sad day when removing a pump from the aircraft is too much = effort to investigate an anomaly.=20 Wolfgang wrote:<> As aircraft owners we are responsible for knowing the = configuration of the aircraft systems. If something is out of the = ordinary, investigate. We know a lot about what the configuration = should be and how it works and behaves. We also know of configurations = that do not work. You may very well be holding the key to a new, as of = yet, unidentified failure mode, but we may never know. Wolfgang wrote: <> If my tire has a flat and I see a nail sticking through the side = wall, I am rather confident in assuming the nail was the source of my = leak. Likewise, if I open up a lock-up prone pump and find return = springs, I will have a high degree of confidence I have found the source = of the problem. Could there be a second cause? Possibly, but as of = yet, none have been documented. Wolfgang wrote:<<=E2=80=A6original suspicion of the spool coming = off it's end point (with the help of springs and airframe vibration) is = in fact what's causing the problem.>> Springs definitely - that is what they were designed to do. = Oildyne started adding springs to center the spool to the Legacy pump in = ~2003. Our system will eventually fail if these springs are installed. = Fortunately the vast majority of our pumps do not have them. If you = have springs installed, simply remove them. Vibration - the evidence says otherwise. Measurements of various = spool and pump combinations required from 13 g's (9 year old 'soft' = o-ring) to 70 g's (new 'stiff' o-ring) to move the spool. Aircraft = vibration at the pump was measured to be +/- 0.1 g (flying) to +/-1.3 g = (engine start). Vibration is not nearly sufficient to have any effect on = the spool.=20 Wolfgang wrote:<> The springs are very strong, 26 lb/in. Wolfgang wrote:<> See MIL-STD-810 for expected vibration levels in aircraft = environments. =20 Wolfgang wrote:<> I would still like to know how push buttons can overload anything. = And why would anyone want to override more than one at a time? Wolfgang wrote:< I have never had a thermal lock up, yet I use pressure gauges and = the momentary push buttons on a regular basis. They were originally = installed to deal with sticking VEP switches, but it is like getting a = new tool. After you have it, you can't imagine how you lived without = out it. I have already discussed the benefits of momentary switches not = related to hydraulic lock-up. Wolfgang wrote:<> One should label the push buttons appropriately. Wolfgang wrote:<> Recall that the Legacy pump configuration =E2=80=9CCZZ=E2=80=9D is = proprietary to Lancair. Companies generally don=E2=80=99t post = proprietary materials on-line. <> Not really. I avoid them by thorough examination, no matter what = it requires. Chris Zavatson N91CZ 360std www.N91CZ.net ------=_NextPart_000_003F_01CCFEBC.498288E0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Chris,
 
You refer to a CZZ configuration but I = don't find=20 any such CZZ reference in the Oildyne spec sheet. Can you elaborate=20 ?
 
Wolfgang
 
----- Original Message -----
From:=20 Chris=20 Zavatson
Sent: Friday, March 09, 2012 = 11:06=20 AM
Subject: Re: [LML] Re: 320/360 = Hydraulic=20 Pressure Switch

This = first video shows=20 the stock LB configuration operating normally while going through = multiple=20 extreme thermal cycles both retracted and extended.  Note that the = non-pressurized side=20 remains at zero pressure throughout the entire test.   The pump = responds, hot or=20 cold, retracted or extended.
htt= p://www.n91cz.com/Hydraulics/Thermal%20Cycling%20IIII.wmv
This = second video shows=20 the CZZ configuration used on the Legacy which adds return springs to = the LB=20 spool (actually LD, in this case) and removes the back pressure feed = in the=20 return line.  This = configuration=20 is not compatible with the 320/360 hydraulic system.  As shown in the video, this=20 configuration locks up.  = Note that=20 the both high and low sides rise and fall with temperature.  Once the pressure rises = above the=20 pressure switch set points, the pump cannot be engaged. 
http://ww= w.n91cz.com/Hydraulics/NewPumpLockUp_0001.wmv
Reverting the CZZ configuration back to the 320/360 = configuration=20 took about 10 minutes.
http://www.n91cz= .com/Hydraulics/Pump-Unlock.pdf
Once the = 320/360 pump=20 configuration incorporated the LB back pressure circuit, it became an=20 incredibly reliable and trouble free part of the aircraft design.  It has tens, perhaps, = hundreds of=20 thousands of hours of trouble free service.  I gladly = contributed=20 1,350 of those hours.
I am not = advocating any=20 =E2=80=98fix=E2=80=99 and certainly not any modification.  Quite the = contrary, I=20 have never found the stock LB configuration to need a fix.  I do advocate = ensuring the=20 proper configuration and proper adjustments are maintained. 
Over the = years, I have=20 helped many Lancair owners resolve hydraulic issues.   I = have found=20 assembly errors (reversed spool valve), bad poppet valves, pressure = switch=20 issues, both adjustment errors and failures, faulty relays, hydraulic = cylinder=20 issues, even leaking dump valves.  Not once was = the problem=20 tied to the pump design. =20
I think = it is a matter=20 of maintenance philosophy.
Chris Zavatson
N91CZ
360std
www.N91CZ.net

From: Wolfgang=20 <Wolfgang@MiCom.net>
To: lml@lancaironline.net =
Sent: Tuesday, March 6, 2012 = 11:02=20 AM
Subject: [LML] = Re: 320/360=20 Hydraulic Pressure Switch

=EF=BB=BF=20
It's a matter of cost effectiveness. = I'm still=20 waiting for positive evidence of what exactly is causing the failure = so your=20 fix can be validated.
Again, I have come up with a fix that = WILL fix=20 that problem . . . for less than what it costs to "fix" the pump, not = to=20 mention down time . . . assuming that springs and vibration is = what's=20 causing the problem. But you have said that vibration can't do that ?=20 ?
 
Your "fix" could be the answer but = there is no=20 way to know for sure what is inside a particular pump without a = dissection=20 because part numbers are not reliable.
 
I'm thinking the springs are the = culprit but that=20 needs to be demonstrated. The springs with the help of vibration are = the only=20 thing that I can think of that can move the spindle off it's end = position=20 against O-ring friction. I'm thinking that no springs and maybe harder = O-rings=20 could be the answer. That scenario makes sense to me.
 
You have the test rig you made up so = why don't=20 you simulate the supposed problem and implement the supposed fix and = document=20 for all what the "correct" answer is ?
Let us know if your approach = WILL fix the=20 problem.
 
I have already done that with my = electric=20 module.
 
Assuming the pump modification is a = valid=20 fix,
which is more cost=20 effective, remove, dissect, re-assemble, replace the pump=20
or simply add the = electric module using it's=20 push-on connectors ?
 
Wolfgang
 
----- Original Message -----
Sent: Monday, March 05, 2012 = 8:21=20 AM
Subject: Re: [LML] Re: = 320/360=20 Hydraulic Pressure Switch

Wolfgang,
If a mechanic were to install a new cylinder on my = plane using=20 incorrect rings that subsequently led to oil consumption of 2 qt/hr, = I could=20 theoretically design a system that refills the sump to assure I = don=E2=80=99t run=20 out of oil during long flights.  The more = customary=20 approach would be to remove the cylinder and install the correct=20 rings.
The =E2=80=98problem=E2=80=99 here is not that oil = needs to be=20 replenished.  The problem is the installation of = incorrect=20 parts.  The =E2=80=98fix=E2=80=99 is not to add a = system to keep the sump=20 replenished.  The fix is to use the correct=20 rings.
Chris Zavatson
N91CZ
360std
 
 
From: Wolfgang=20 <Wolfgang@MiCom.net>
To: lml@lancaironline.net =
Sent: Saturday, March 3, 2012 = 4:01=20 PM
Subject: [LML] = Re:=20 320/360 Hydraulic Pressure Switch

=EF=BB=BF=20
Chris,
 
Life is complicated enough so when = I fly, I=20 like to enjoy it. Being a slave to the system like a cog in a flying = machine=20 is not my idea of "enjoyment". Don't get me wrong, I like getting = into=20 technicals up to my eyebrows, but I prefer to do that at my = choosing, not=20 while tending to a malfunction in flight. That's why I cane up with = the gear=20 module.
 
After you detailed the presence of = springs in=20 the pump to help center the spool and popets, I see that my original = supposition that the spool is coming off it's end position is = confirmed. It=20 looks like the springs are in fact, capable of overcoming the = friction of=20 the O-rings. You keep measuring the forces in G's but that does not = give us=20 an actual force measurement that is what the springs are operating = against.=20
 
It remains that some pump = installations have=20 the problem of the spool not maintaining the required position for = safe=20 flight operations. You have come up with many details that go toward = esplaining the problem and a possible fix (take out the springs). I = have=20 come up with a module that WILL fix that problem.
 
Wolfgang
 
----- Original Message ----- =
From: = Chris=20 Zavatson
Sent: Friday, March 02, = 2012 7:54=20 AM
Subject: [LML] Re: 320/360 = Hydraulic=20 Pressure Switch

Wolfgang,=20
 
It is a=20 sad day when removing a pump from the aircraft is too much effort = to=20 investigate an anomaly. =
 
Wolfgang=20 wrote:<<We would all like to get at the root cause of the = problem=20 but, as yet, that hasn't happened. Likely because it's too much = work to=20 track down the actual cause and fix it. = =E2=80=A6>>
 
As=20 aircraft owners we are responsible for knowing the configuration = of the=20 aircraft systems.  If something is out of the ordinary,=20 investigate.  We know a lot about what the configuration = should be=20 and how it works and behaves.  We also know of=20 configurations that do not work.  You = may very well=20 be holding the key to a new, as of yet, unidentified failure = mode,=20 but we may never know.
 
Wolfgang=20 wrote:=20 <<So far we only have a good plausible theory missing only=20 demonstratable proof.>>
 
If my tire = has a flat=20 and I see a nail sticking through the side wall, I am rather = confident in=20 assuming the nail was the source of my leak.  = Likewise,=20 if I open up a lock-up prone pump and find return springs, I will = have a=20 high degree of confidence I have found the source of the=20 problem.  Could there be a second = cause? =20 Possibly, but as of yet,=20 none have been documented.
 
Wolfgang=20 wrote:<<=E2=80=A6original suspicion of the spool coming off = it's end point=20 (with the help of springs and airframe vibration) is in fact = what's=20 causing the problem.>>
 
Springs=20 definitely - that is what they were designed to do.=20  Oildyne started adding springs to center the = spool to=20 the Legacy pump in ~2003.  Our system will = eventually=20 fail if these springs are installed. Fortunately the vast majority = of our=20 pumps do not have them.  If you have springs = installed,=20 simply remove them.
 
Vibration=20 - the evidence says otherwise.  Measurements of various spool = and=20 pump combinations required from 13 g's (9 year old = 'soft'=20 o-ring) to 70 g's (new 'stiff' o-ring) to move the = spool. =20 Aircraft vibration at the pump was measured to be +/- 0.1 g = (flying) to=20 +/-1.3 g (engine start). Vibration is not = nearly sufficient to=20 have any effect on the spool. 
 
Wolfgang=20 wrote:<<If it takes that much force to move the spindle = against the=20 O-rings then those springs must be pretty darn strong. I find that = dificult to accept.>>
The=20 springs are very strong, 26 lb/in.
 
Wolfgang=20 wrote:<<Vibration=20 levels can exceed 70 G's>>
See=20 MIL-STD-810 for expected vibration levels in aircraft=20 environments.
  
Wolfgang=20 wrote:<<Yes, that would be easy . . . except . . . you can = only=20 override one pressure switch at a time or overload the=20 system>>
I would=20 still like to know how push buttons can overload = anything.  And=20 why would anyone want to override more than one at a = time?
 
Wolfgang=20 wrote:<<The items you cited are more a one-of condition=20 ...>
I have=20 never had a thermal lock up, yet I use pressure gauges and the = momentary=20 push buttons on a regular basis.  They were originally = installed to=20 deal with sticking VEP switches, but it is like getting a new = tool. =20 After you have it, you can't imagine how you lived without out = it.  I=20 have already discussed the benefits of momentary switches not = related to=20 hydraulic lock-up.
 
Wolfgang=20 wrote:<<In the event of a problem you have to make sure you = push the=20 right switch.>>
One=20 should label the push buttons appropriately.
 
Wolfgang=20 wrote:<<Are you saying that Oildyne is putting springs in = the spool=20 to center it when the pump is not running ?
Springs=20 that are not documented in the Oildyne spec sheet=20 ?>>
Recall=20 that the Legacy pump configuration =E2=80=9CCZZ=E2=80=9D is = proprietary to=20 Lancair.  Companies generally don=E2=80=99t post = proprietary=20 materials on-line.
 
<<You=20 seem to want to be "involved" in the anomalies of=20 flight.>>
Not=20 really.  I avoid them by thorough examination, = no matter=20 what it requires.
 
Chris=20 Zavatson
N91CZ
360std
www.N91CZ.net
 
 



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