X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 07 Sep 2012 16:46:49 -0400 Message-ID: X-Original-Return-Path: Received: from mail-ey0-f180.google.com ([209.85.215.180] verified) by logan.com (CommuniGate Pro SMTP 6.0c1) with ESMTPS id 5749822 for lml@lancaironline.net; Fri, 07 Sep 2012 14:32:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.180; envelope-from=dballin@gmail.com Received: by eaad13 with SMTP id d13so842352eaa.25 for ; Fri, 07 Sep 2012 11:31:58 -0700 (PDT) Received: by 10.204.129.27 with SMTP id m27mr2973605bks.115.1347042718167; Fri, 07 Sep 2012 11:31:58 -0700 (PDT) MIME-Version: 1.0 Received: by 10.204.5.195 with HTTP; Fri, 7 Sep 2012 11:31:36 -0700 (PDT) Reply-To: dballin@gmail.com In-Reply-To: References: From: Dan Ballin X-Original-Date: Fri, 7 Sep 2012 11:31:36 -0700 X-Original-Message-ID: Subject: Re: [LML] Re: Thermal influence on Hydraulic Pressure X-Original-To: Lancair Mailing List Content-Type: multipart/alternative; boundary=001517475406b6b25d04c920d284 --001517475406b6b25d04c920d284 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Oh he has a kit he will sell you that does something to the hydraulic system. I'd have to go through the archives to see what it is. Might be worth it for your plane since this seems to be a recurrent problem. Dan On Fri, Sep 7, 2012 at 11:13 AM, Ralph Love w= rote: > Robert, > Do you see a solution here? > R > > On Sep 7, 2012, at 10:38 AM, "Wolfgang" wrote: > > I have said it before, removing a pump and taking it apart to fix a > supposed design problem, putting the aircraft down for the duration, is n= ot > always the best solution. After it's apart, you're still looking to verif= y > your supposition. Installing a fix like mine guarantees a solution in abo= ut > 30 minutes. Pilot's choice. 30 minutes is a small price to pay. > > Wolfgang > > > ----- Original Message ----- > *From:* Chris Zavatson > *To:* lml@lancaironline.net > *Sent:* Thursday, September 06, 2012 8:15 AM > *Subject:* Re: [LML] Re: Thermal influence on Hydraulic Pressure > > Wolfgang, > The =91failure to retract=92 issue, to which you refer, sounds like a pum= p > configuration issue. > For example, the current pump sold by Lancair for the 320/360/Legacy > contains spool return springs. This configuration has the potential to > lock up due to thermal heating. This configuration is simply not > compatible with the design of the Lancair two-seat hydraulic systems. > Lock-up video:http://www.n91cz.com/Hydraulics/NewPumpLockUp_0001.wmv > With personnel turn-over at both companies, neither side knows why the > return springs were added. However, both Parker and Lancair agree that a > lock up on the ground is possible with the springs installed. This > lock-up has been experienced by some, including the factory Legacy. It > just has not been reported enough to drive an engineering change at Lanca= ir. > > Parker has graciously supplied parts to revert currently sold =93CZZ=94 p= umps > back to the original 320/360 configuration with respect to spool operatio= n. > I have been forwarding these parts free of charge to anyone who needs > them. > See conversion instructions here: > http://www.n91cz.com/Hydraulics/Pump-Unlock.pdf > I applaud your ingenuity in devising your circuit. Unfortunately your > energy seems to be a little misplaced. I would prefer to investigate > and fix the root cause of any out of the ordinary behavior-especially on = an > airplane! If my engine was burning a quart of oil per hour, the > fix would not to design a gadget that would pump oil from an onboard supp= ly > into the sump and replenish the lost oil. The solution, albeit painful > in the short term, would be to open up the engine, find and fix the probl= em > and then fly like other engines. > I understand that removing a pump, in particular those mounted behind the > baggage bulkhead is no fun. Poor access is a real deterrent for any > maintenance activity. That is simply human nature. In the grand scheme > of things, it is a small price to pay. > My offer still stands to examine your (Lorn=92s) pump or any other that i= s > able to lock-up both circuits. I have not yet come across one that did > not have an obvious cause-like the springs mentioned above, so any such > reported behavior of great interest to me and is worth investigating. > **** > Chris Zavatson > N91CZ > 360std > www.N91CZ.net > > > *From:* Wolfgang > *To:* lml@lancaironline.net > *Sent:* Wednesday, September 5, 2012 9:28 AM > *Subject:* [LML] Re: Thermal influence on Hydraulic Pressure > ** > Let's not forget this thermal influence causing non-function can also > happen in reverse. It has been reported that a thermal a soak on the grou= nd > after a cold night can and has caused a failure to retract after take off= . > > A while back I offered a solution of bumping the pump automatically > whenever both pressure switches, HI and LO, are open due to high pressure= . > This would put the system back in normal operation mode without the need > for pilot intervention > > Wolfgang > > > ----- Original Message ----- > *From:* Chris Zavatson > *To:* lml@lancaironline.net > *Sent:* Tuesday, September 04, 2012 7:53 PM > *Subject:* Re: [LML] Re: Thermal influence on Hydraulic Pressure > > Fred, > I wish we had an easy way of bleeding just a wee bit of pressure without > momentarily dumping the gear in cruise. > The 320/360 pumps use a non-adjustable thermal relief valve rated at 2,50= 0 > psi. The actual cracking pressure is 2,500 to 2,900 psi. This is the > lowest set-point Parker has available. 2,900 psi is a lot of pressure fo= r > a system that nominally operates at 1,200 psi. Hopefully the design marg= in > for the cylinders etc. was chosen large enough. > The first time I saw a 2,000+ excursion was on the test bench. I was lea= k > checking a cylinder. The test stand was near the hangar door. The sun > swung around and hit the pressurized clyinder. I dont' know what the max > pressure was since that gauge only went to 2,000 psi. > Chris > > Chris Zavatson > N91CZ > 360std > http://www.n91cz.net/ > > *From:* Frederick Moreno > *To:* lml@lancaironline.net > *Sent:* Monday, September 3, 2012 11:54 AM > *Subject:* [LML] Re: Thermal influence on Hydraulic Pressure > > I have an MPV-50 engine monitor that includes continuous reading of the > hydraulic system pressure on my Lancair IV/ I have seen the same thing= , > particularly on a flight that started on a cool morning departure from my > home drome and took us to the desert for a 110+F day. On descent, pressu= re > rose from its customary 1250 to 1500 psi at which point Bitching Betty > started to complain so I bumped my speed brakes which are hydraulic, and > lowered pressure back down to my customary range. Same thing sometimes > happens in reverse, a hot soak on the ground, then a climb to 10-11,000 > feet for a cool soak, and at some point the hydraulic pump kicks on to > restore pressure to the desired level. My TR-182 used to the the same > thing routinely when departing Phoenix in the summertime. > > It is a real effect, and makes one wonder about very high pressure events > arising from FL 270 (say) cold soak terminating in Phoenix on a July > afternoon. Hmmmm.... > > Fred > > > > > *-------Original Message-------* > > > -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. > > Chris Zavatson > N91CZ > 360std > http://www.n91cz.net/ > > > **** > > --001517475406b6b25d04c920d284 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Oh he has a kit he will sell you that does something to the hydraulic syste= m.=A0 I'd have to go through the archives to see what it is.=A0 Might b= e worth it for your plane since this seems to be a recurrent problem.
Dan

On Fri, Sep 7, 2012 at 11:13 AM, Ralp= h Love <ralphlove@stanfordalumni.org> wrote:
<= blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px= #ccc solid;padding-left:1ex">
Robert,
Do you see a solution here?=
R

On Sep 7, 2012, at 10:38 AM, "Wolfgang"= ; <Wolfgang@MiCo= m.net> wrote:

I have said it before, removing a pump and taking= =20 it apart to fix a supposed design problem, putting the aircraft down for th= e=20 duration, is not always the best solution. After it's apart, you're= still=20 looking to verify your supposition. Installing a fix like mine guarantees a= =20 solution in about 30 minutes. Pilot's choice. 30 minutes is a small pri= ce to=20 pay.
=A0
Wolfgang
=A0
----- Original Message -----
Sent: Thursday, September 06, 2012 = 8:15=20 AM
Subject: Re: [LML] Re: Thermal infl= uence=20 on Hydraulic Pressure

Wolfgang,
The=20 =91failure to retract=92 issue, to which you refer, sounds like a pump=20 configuration issue.=A0=20
For example, the current pump sold by Lancair=20 for the 320/360/Legacy contains spool return springs.=A0 =A0=A0This configuration has the=20 potential to lock up due to thermal heating.=A0 This configu= ration is simply not=20 compatible with the design of the Lancair two-seat hydraulic systems.=A0
Lock-up video:http://www.n91cz.com/Hydraulics= /NewPumpLockUp_0001.wmv
With personnel turn-over at both companies,=20 neither side knows why the return springs were added.=A0 How= ever, both Parker and Lancair agree=20 that a lock up on the ground is possible with the springs installed.=A0 This lock-up has been experienced by=20 some, including the factory Legacy.=A0=20 It just has not been reported enough to drive an engineering chang= e at=20 Lancair.=A0
Parker=20 has graciously supplied parts to revert currently sold =93CZZ=94 pumps ba= ck to the=20 original 320/360 configuration with respect to spool operation.=A0 = I have been forwarding these parts=20 free of charge to anyone who needs them.
See conversion instructions here: http://www.n91cz.com/Hydraulics/P= ump-Unlock.pdf
I applaud your ingenuity in devising your=20 circuit.=A0 Unfortunately your=20 energy seems to be a little misplaced.=A0=A0 I would prefer = to investigate=20 and fix the root cause of any out of the ordinary behavior-especially on = an=20 airplane!=A0=A0 If my engine was=20 burning a quart of oil per hour, the fix=A0would not to design a gadget= =20 that would pump oil from an onboard supply into the sump and replenish th= e=20 lost oil.=A0 The solution, albeit=20 painful in the short term,=A0would be=A0to open up the engine, find and= =20 fix the problem and then fly like other engines.
I understand that removing a pump, in=20 particular those mounted behind the baggage bulkhead is no fun.=A0 = Poor access is a real deterrent for=20 any maintenance activity.=A0 That is=20 simply human nature.=A0 In the grand=20 scheme of things, it is a small price to pay.=A0
My offer still stands to examine your=20 (Lorn=92s) pump or any other that is able to lock-up both circuits.= =A0 I have not yet come=20 across one that did not have an obvious cause-like the springs mentioned= =20 above, so any such reported behavior of great interest to me and is worth= =20 investigating.
=A0
Chris=20 Zavatson
N91CZ
360std
www.N91CZ.net


Let's not forget this thermal influence cau= sing=20 non-function can also happen in reverse. It has been reported that a ther= mal a=20 soak on the ground after a cold night can and has caused a failure to ret= ract=20 after take off.
=A0
A while back I offered a solution of bumping th= e=20 pump automatically whenever both pressure switches, HI and LO, are open d= ue to=20 high pressure. This would=A0put the system back in normal operation mode= =20 without the need for pilot intervention
=A0
Wolfgang
=A0
----- Original Message -----
Sent: Tuesday, September 04, 2012= 7:53=20 PM
Subject: Re: [LML] Re: Thermal=20 influence on Hydraulic Pressure

Fred,
I wish we had an easy way of bleeding just a wee = bit of pressure=20 without momentarily dumping the gear in cruise.
The=20 320/360 pumps use a non-adjustable thermal relief valve rated at 2,500= =20 psi.=A0 The actual cracking pressure is 2,500 to 2,900 psi.=A0 This is= =20 the lowest=A0set-point Parker has available.=A0 2,900 psi is a lot of= =20 pressure for a system that nominally operates at 1,200 psi.=A0 Hopefull= y=20 the design margin for the cylinders etc.=A0was chosen=A0large=20 enough.
The=20 first time I saw a 2,000+ excursion was on the test bench.=A0 I was lea= k=20 checking a cylinder.=A0 The test stand was near the hangar door.=A0=20 The sun swung=A0around and hit the pressurized clyinder.=A0 I dont'= =20 know what the max pressure was since that gauge only went to 2,000=20 psi.
Chris
=A0
Chris=20 Zavatson
N91CZ
360std

From: Frederick Moreno= =20 <fr= ederickmoreno@bigpond.com>
To= : lml= @lancaironline.net
Sent: Monday, September 3, 2= 012 11:54=20 AM
Subject: [LML] Re:= =20 Thermal influence on Hydraulic Pressure
=20
<SENDER_EMAILfrederi= ckmoreno>
I have an MPV-50=A0 engine monitor that includes continuous= =20 reading of the hydraulic system pressure on my Lancair IV/=A0=A0= =20 =A0I have seen the same thing, particularly on a flight that=20 started on a cool morning departure from my home drome and took u= s to=20 the desert for a 110+F day.=A0 On descent, pressure rose from its= =20 customary 1250 to 1500 psi at which point Bitching Betty started = to=20 complain so I bumped my speed brakes which are hydraulic, and=20 lowered=A0pressure back down to my customary range.=A0=A0=20 Same thing sometimes happens in reverse, a hot soak on the ground= ,=20 then a climb to 10-11,000 feet for a cool soak, and at some point= =20 the=A0hydraulic pump kicks on to restore pressure to the desired= =20 level.=A0 My TR-182 used to the the same thing routinely when=20 departing Phoenix in the summertime.
=A0
It is a real effect, and makes one wonder about very high=20 pressure events arising from FL 270 (say) cold soak terminating i= n=20 Phoenix on a July afternoon.=A0 Hmmmm....
=A0
Fred
=A0
=A0
=A0
=A0
-------Original=20 Message-------
=A0
=A0
-took this photo after=A0a descent from 16.5k to 1,500=20 ft.
OAT=A0went 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 ra= mp in=20 Spokane.=A0After sitting for an hour, the low pressure gauge was= =20 pegged at 1,200 psi+.=A0 Spokane might not be the warmest spot in= =20 the country, but at 85 deg F, it was 55 degrees warmer than the c= old=20 soak on the previous leg.
Temperature changes have a big impact on system=20 pressure.=A0
=A0
Chris Zavatson
N91CZ
360std
=A0

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