X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 13 Feb 2012 14:15:38 -0500 Message-ID: X-Original-Return-Path: Received: from raven.ravenwebhosting.com ([72.9.254.67] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTPS id 5394596 for lml@lancaironline.net; Mon, 13 Feb 2012 14:06:11 -0500 Received-SPF: none receiver=logan.com; client-ip=72.9.254.67; envelope-from=paul@tbm700.com Received: from 103-57.202-68.tampabay.res.rr.com ([68.202.57.103]:52190 helo=[192.168.15.101]) by raven.ravenwebhosting.com with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.69) (envelope-from ) id 1Rx1DW-000284-Cp for lml@lancaironline.net; Mon, 13 Feb 2012 14:05:38 -0500 From: paul miller Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-19-812900568 Subject: Re: [LML] Re: 320/360 Hydraulic Pressure Switch X-Original-Date: Mon, 13 Feb 2012 14:05:35 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <0A54B90A-4062-4261-B0B4-B3B86C672620@tbm700.com> X-Mailer: Apple Mail (2.1084) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - raven.ravenwebhosting.com X-AntiAbuse: Original Domain - lancaironline.net X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - tbm700.com X-Source: X-Source-Args: X-Source-Dir: --Apple-Mail-19-812900568 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 Chris: I really appreciate all the work going into this analysis. I = keep trying to ascertain if any of this issue is part of the Legacy heat = issue where I have to bleed the dump valve after a temp change on the = ramp. Is this related in your opinion? Paul Spruce Creek On 2012-02-13, at 9:23 AM, Chris Zavatson wrote: > Wolfgang, > =20 > I would like nothing better than to get at the root cause for those = pumps exhibitng a system lock-up. > We can show by analysis and test that when both poppets are allowed to = close, the hydraulic system will lock up on the ground when heated. > We can also show by analysis and test that if the spool remains in its = last commanded position that a lock up cannot occur. > We have measured the force it takes to move a spool on a number of = different pumps and configurations and foud the force far exceeds what = can be expected by airframe vibration.=20 > =20 > It seems to me one should examine in detail any pump that acts = differently than the general fleet. If I owned one hundred identical = aircraft and one exhibited low fuel pressure, I would not redesign the = fuel system for the entire fleet in response. Rather, I would examine = why the one was different. Likewise, when a pump allows the hydraulic = system to lock-up, the proper thing to do would be to examine that pump = in great detail and determine how it differs from the rest. I have a = standing offer on the table to examine and test any pump that exhibits = this behavior. While I have examined pumps for other reasons, I have = not yet had the opportunity to look at one that has been known to a = cause a lock up. I am really curious to see what the differences are = and if they have any implications for the rest of the Lancair fleet.=20 > =20 > There is no need to further test a pump with return springs. We know = what can happen. Note 'can happen'. The system will not lock up every = time, in fact, it will be very infrequent. Several conditions must be = met. While the return springs, at 26 lb/in, are strong enough to get = the spool moving towards center, they do not always make it all the way. = After all, spring force is a function of deflection. Near center, they = run out of steam. On occasion, I had to add some vibration to lock both = poppets.=20 > The vibration levels required to move a spool without a spring are = enormous. Those levels would likely destroy the motor assembly, not to = mention the pressure switches, avionics and so on. > Until we can examine a mis-behaving pump and compare certain = parameters, the root cause for that pump will indeed be unknown. = Fortunately, we know a great deal about how properly behaving pumps = operate and what configurations will cause problems. Hypothesizing = about a failure mode without being willing to examine the pump itself is = rather pointless. > =20 > Chris Zavatson > N91CZ > 360std > www.N91CZ.net > =20 > =20 >=20 > From: Wolfgang > To: lml@lancaironline.net=20 > Sent: Friday, February 10, 2012 7:26 AM > Subject: [LML] Re: 320/360 Hydraulic Pressure Switch > If it takes that much force to move the spindle against the O-rings = then those springs must be pretty darn strong. I find that dificult to = accept. > =20 > Still, that port with the added spring, I believe it's a return port = for excess hydraulic fluid that can be used with a three port dump = valve. > . . . but why the spring if it's plugged anyway ? > =20 > If the ultimate answer is to remove the "extra" springs, then let's = demonstrate that by testing a pump with the springs under pressure, = heat, AND simulated engine vibration. Short of that, this failure mode = remains a question. > =20 > Wolfgang >=20 > =20 > From: Chris Zavatson > Sender: > Subject: Re: [LML] Fw: [LML] Re: 320/360 Hydraulic Pressure = Switch > Date: Wed, 08 Feb 2012 08:05:15 -0500 > To: lml@lancaironline.net > Wolfgang, > The ball and spring go in the port labeled "Cavity "E" Back-Pressure". = This is the pipe plug that sits in between the two output ports. > =20 > You might consider securing the dump valve with a secondary locking = feature. It too relies on friction alone to stay in position. = Seriously, given the force it takes to move the spool, if mine were not = staying put, I would want to know why.=20 > =20 > =46rom previous measurements: > Using O-ring 013-70 requires 30 g's to move the spool. > Using O-ring 013-90 requires 70 g's to move the spool. > The 013-90 is specified for pumps with back pressure circuits such as = we have. > =20 > Chris Zavatson > N91CZ > 360std > www.N91CZ.net > =20 > From: Wolfgang > To: lml@lancaironline.net=20 > Sent: Monday, February 6, 2012 9:24 AM > Subject: [LML] Fw: [LML] Re: 320/360 Hydraulic Pressure Switch > I see the centering springs but what about the added spring, eyelet = and ball ? Where does that fit into the schematic ? > =20 > I still don't like the idea of friction being the only thing keeping = spindle at it's end point. Sure, removing the springs will help but a = positive system to pressure the spindle back into it's required position = automatically as needed still seems prudent. > =20 > Wolfgang > =20 > ----- Original Message ----- > From: Chris Zavatson > To: lml@lancaironline.net > Sent: Sunday, February 05, 2012 8:34 AM > Subject: Re: [LML] Re: 320/360 Hydraulic Pressure Switch > Several folks have been asking privately about the spool centering = springs mentioned below. This link contains both schematics and photos = showing how to revert a new pump back to the original 320/360 = functionality.=20 > http://www.n91cz.com/Hydraulics/Pump-Unlock.pdf > =20 > Chris Zavatson > N91CZ > 360std > www.N91CZ.net > From: Chris Zavatson > To: lml@lancaironline.net=20 > Sent: Wednesday, February 1, 2012 12:46 PM > Subject: [LML] Re: 320/360 Hydraulic Pressure Switch > Lorn, > Had the temperature been 90 or 100 degrees your pressure would have = been even higher. In some of my hydraulics videos, you will see the = 2,000 psi gauge pegged on occasion during thermal heating tests. > =20 > http://www.n91cz.com/Hydraulics/Lancair_Hydraulics.htm > =20 > Your predicament of having to crack a hydraulic line is exactly what = can happen if the spool centers after pump shut down. I find that a = completely unacceptable design. Imagine taking off into IMC and the = gear won't come up. I had the opportunity to test out a pump in this = configuration last summer. Just as you experienced, I was able to = reproduce a complete lock up.=20 > http://www.n91cz.com/Hydraulics/NewPumpLockUp_0001.wmv - hi res > http://www.n91cz.com/Hydraulics/NewPumpLockUp_0002.wmv - low res > =20 > After discussions with Lancair and Parker, I reverted the = configuration back to the original 320/360 config and all is good now. = Only one side can ever be pressurized at a time. Unfortunately due to = employee turn-over, no one currently at Parker or Lancair knows why the = centering springs were added. After reviewing the 320/360 system both = agreed that a system lock up is possible using replacement pumps = currently sold (108AMS32-CZZ-3V-14-08-Y). Parker sent me parts to = revert three pumps back to the original configuration.=20 > =20 > The TRVs in our pumps are the lowest available -fixed setting of 2,500 = psi. This may be too high to protect some of our components. I have = run them up to 2,000 psi. In flight, I have seen 1,800 psi, descending = from 18k into the southwest deserts. > =20 > Chris Zavatson > N91CZ > 360std > www.N91CZ.net > =20 > =20 > From: Lorn H Olsen > To: lml@lancaironline.net=20 > Sent: Wednesday, February 1, 2012 6:33 AM > Subject: [LML] Re: 320/360 Hydraulic Pressure Switch > Again,My Oildyne internal pressure switch came (set by Oildyne) at = 1,500 PSI. How do I know? I parked my plane on the ramp at Newport News, = Va in the evening. The temperature was 40=B0F. 3 days later, when I was = going to take off. The temperature was 80=B0F. I looked at my pressure = gauges. Both the up and down were at 1,500 PSI. I had to crack a nut in = a hydraulic line to release the pressure. The gear would not go up or = down, at this pressure. The emergency dump valve would not release, at = this pressure. The pump would not run at all, at this pressure.Now, I = have Wolfgang's high pressure adapter in the system. It runs the pump = whenever the pressure is high on both the up and the down side.There is = no speculation here. Just the facts, mam.--Lorn H. 'Feathers' Olsen, = MAA, ASMEL, ASES, Comm, InstDynaComm, Corp., 248-345-0500, = mailto:lorn@dynacomm.usLNC2, FB90/92, O-320-D1F, 1,800 hrs, N31161, Y47, = SE Michigan --Apple-Mail-19-812900568 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=iso-8859-1
Wolfgang,
 
I would like = nothing better than to get at the root cause for those pumps exhibitng a = system lock-up.
We can show by analysis and test that when both poppets = are allowed to close, the hydraulic system will lock up on the = ground when heated.
We can also = show by analysis and test that if the = spool remains in its last commanded position that a lock up cannot = occur.
We have measured = the force it takes to move a spool on a number of different pumps = and configurations and foud the force far exceeds what can be = expected by airframe vibration. 
 
It seems to me = one should examine in detail any pump that acts differently than the = general fleet.  If I owned one hundred identical aircraft = and one exhibited low fuel pressure, I would not redesign the fuel = system for the entire fleet in response.  Rather, I would = examine why the one was different.  Likewise, = when a pump allows the hydraulic = system to lock-up, the proper thing to do would be to examine that pump = in great detail and determine how it differs from the rest.  I have = a standing offer on the table to examine and test any pump that = exhibits this behavior.  While I have examined pumps for = other reasons, I have not yet had the opportunity to look at one that = has been known to a cause a lock up.  I am really curious to see what the differences are and if they = have any implications for the rest of the = Lancair fleet. 
 
There is no need = to further test a pump with return springs.  We know what = can happen.  Note 'can happen'.  The system will not lock = up every time, in fact, it will be very infrequent.  Several = conditions must be met.  While the return springs, at 26 lb/in, are = strong enough  to get the spool moving towards center, they do not = always make it all the way.  After all, spring force is a function = of deflection.  Near center, they run out of steam.  On occasion, I = had to add some vibration to lock both poppets. 
The vibration = levels required to move a spool without a spring are enormous.  Those = levels would likely destroy the motor assembly, not to mention the = pressure switches, avionics and so on.
Until we can = examine a mis-behaving pump and compare certain parameters, the root = cause for that pump will indeed be unknown.  Fortunately, we know a = great deal about how properly behaving pumps operate and what = configurations will cause problems.  Hypothesizing about a failure = mode without being willing to examine the pump itself is rather = pointless.
 
Chris = Zavatson
N91CZ
360std
 
  =

From: Wolfgang <Wolfgang@MiCom.net>
To: lml@lancaironline.net =
Sent: Friday, = February 10, 2012 7:26 AM
Subject: [LML] Re: 320/360 Hydraulic Pressure = Switch
If it takes that much force to move the spindle against the O-rings = then those springs must be pretty darn strong. I find that dificult to = accept.
 
Still, that port with the added spring, I believe it's a return = port for excess hydraulic fluid that can be used with a three port dump = valve.
. . . but why the spring if it's plugged anyway ?
 
If the ultimate answer is to remove the "extra" springs, then let's = demonstrate that by testing a pump with the springs under pressure, = heat, AND simulated engine vibration. Short of that, this failure mode = remains a question.
 
Wolfgang

 
= <= /tbody>
From: Chris Zavatson <chris_zavatson@yahoo.com><= /td>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Fw: [LML] Re: 320/360 = Hydraulic Pressure Switch
Date: Wed, 08 Feb 2012 08:05:15 = -0500
To: lml@lancaironline.net
Wolfgang,
The ball and spring go in the port labeled "Cavity "E" = Back-Pressure".  This is the pipe plug that sits in between the two = output ports.
 
You might consider = securing the dump valve with a secondary locking feature.  It too = relies on friction alone to stay in position.  Seriously, given the = force it takes to move the spool, if mine were not staying put, I = would want to know why. 
 
=46rom previous measurements:
Using O-ring 013-70 requires 30 g's to move the spool.
Using O-ring 013-90 requires 70 g's to move the spool.=20
The 013-90 is specified for pumps with back pressure circuits = such as we have.
 
Chris = Zavatson
N91CZ
360std
 
=
From: = Wolfgang <Wolfgang@MiCom.net>
= To: lml@lancaironline.net =
Sent: Monday, February 6, 2012 9:24 = AM
Subject: [LML] Fw: [LML] Re: 320/360 Hydraulic = Pressure Switch
I see the centering springs but what about the added spring, eyelet = and ball ? Where does that fit into the schematic ?
 
I still don't like the idea of friction being the only thing = keeping spindle at it's end point. Sure, removing the springs will help = but a positive system to pressure the spindle back into it's required = position automatically as needed still seems prudent.
 
Wolfgang
 
----- Original Message -----=20
Sent: Sunday, February 05, 2012 8:34 AM
Subject: Re: [LML] Re: 320/360 Hydraulic Pressure = Switch
Several folks have been asking privately about the spool centering = springs mentioned below.  This link contains both schematics and = photos showing how to revert a new pump back to the = original 320/360 functionality. 
 
Chris Zavatson
N91CZ
360std
From: Chris = Zavatson <chris_zavatson@yahoo.com>
To: lml@lancaironline.net =
Sent: Wednesday, February 1, 2012 12:46 = PM
Subject: [LML] Re: 320/360 Hydraulic Pressure = Switch
Lorn,
Had the temperature been 90 or 100 degrees your pressure would have = been even higher.  In some of my hydraulics videos, you = will see the 2,000 psi gauge pegged on occasion during thermal = heating tests.
 
 
Your predicament of having to crack a hydraulic line is = exactly what can happen if the spool centers after pump shut down.  = I find that a completely unacceptable design.  Imagine taking off = into IMC and the gear won't come up.  I had the opportunity to test = out a pump in this configuration last summer.  Just as you = experienced, I was able to reproduce a complete lock up. 
 
After discussions with Lancair and Parker, I reverted the = configuration back to the original 320/360 config and all is = good now.  Only one side can ever be pressurized at a time.  = Unfortunately due to employee turn-over, no one currently at Parker or = Lancair knows why the centering springs were added.  After = reviewing the 320/360 system both agreed that a system lock up is = possible using replacement pumps currently sold = (108AMS32-CZZ-3V-14-08-Y).  Parker sent me parts to revert three = pumps back to the original configuration. 
 
The TRVs in our pumps are the lowest available -fixed setting of = 2,500 psi.  This may be too high to protect some of our = components.  I have run them up to 2,000 psi.  = In flight, I have seen 1,800 psi, descending from 18k into the southwest = deserts.
 
Chris Zavatson
N91CZ
360std
 
 
From: Lorn H Olsen <lorn@dynacomm.us>
To:<= /span> lml@lancaironline.net =
Sent: Wednesday, February 1, 2012 6:33 = AM
Subject: [LML] Re: 320/360 Hydraulic Pressure = Switch
Again,My Oildyne internal pressure = switch came (set by Oildyne) at 1,500 PSI. How do I know? I parked my = plane on the ramp at Newport News, Va in the evening. The temperature = was 40=B0F. 3 days later, when I was going to take off. The temperature = was 80=B0F. I looked at my pressure gauges. Both the up and down were at = 1,500 PSI. I had to crack a nut in a hydraulic line to release the = pressure. The gear would not go up or down, at this pressure. The = emergency dump valve would not release, at this pressure. The pump would = not run at all, at this pressure.Now, I have Wolfgang's high = pressure adapter in the system. It runs the pump whenever the pressure is high on both the up = and the down side.There is no speculation here. Just the = facts, mam.--Lorn H. 'Feathers' Olsen, MAA, ASMEL, = ASES, Comm, InstDynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.usLNC2, = FB90/92, O-320-D1F, 1,800 hrs, N31161, Y47, SE = Michigan
<= /div>

= --Apple-Mail-19-812900568--