X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from elasmtp-dupuy.atl.sa.earthlink.net ([209.86.89.62] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTP id 6846848 for lml@lancaironline.net; Fri, 25 Apr 2014 12:15:39 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.62; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=Eb87EVlrHhRPAhGD2/ufcwQC8WxnbN6UefUJAkETdxLNiHQnH7ruJpA5N5wzpHhI; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [71.161.82.155] (helo=[192.168.1.24]) by elasmtp-dupuy.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1WdimF-0004B0-H7 for lml@lancaironline.net; Fri, 25 Apr 2014 12:15:04 -0400 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: multipart/alternative; boundary=Apple-Mail-27--771492378 Subject: Re: [LML] Re: Fw: Gear Down...INOP Date: Fri, 25 Apr 2014 12:15:02 -0400 In-Reply-To: To: "Lancair Mailing List" References: Message-Id: <00BB0DD3-CEA7-44BB-9017-589E46FB2E4B@earthlink.net> X-Mailer: Apple Mail (2.1085) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940e4ed381b67e8ceee143cd6ffcc7bfd03350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 71.161.82.155 --Apple-Mail-27--771492378 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 << below On Apr 25, 2014, at 11:52 AM, Wolfgang wrote: Chris, =20 Why don't we just agree to disagree. I believe in redundancy and it = looks like you don't. << this is bogus. Chris is favoring addressing = the original problem. Redundancy is having a second copy of a known = good design in case the first copy is physically compromised, not = having a work around for a design that is known to have a problem. =20 The pressure pulse you're talking about will subside (glad you agree) = and as it does, because the cylinder is only partially extended, the = cylinder will continues to extend, the low switch will close again, and = enable the pump to continue . . . No, the damage has NOT been done. =20 The only way the switch will stay open (the pressure stays high) is if = there is a physical obstruction preventing the from moving down any = further (like when it is full down). =20 Learn to live with the fact that you're not the only one that knows a = thing or two about airplanes. =20 =20 Wolfgang =20 ----- Original Message ----- From: Chris Zavatson To: lml@lancaironline.net Sent: Thursday, April 24, 2014 8:18 AM Subject: Re: [LML] Fw: Gear Down...INOP Wolfgang, Based on your statement, I don=E2=80=99t think you understand this = failure mode. =E2=80=9C. . but once the pulse subsides (miliseconds) that event is = over because the un-extended gear down cylinder volume will absorb that = pulse.=E2=80=9D Yes, the pulse event is over, but the damage is done. The gear is stuck = partially extended with one pressure switch open and one closed. Your = module WILL NOT clear this problem. We have very different approaches to aircraft operation and maintenance. = I don=E2=80=99t install gadgets to undo a problem after it occurs. I = prevent the problem from occurring in the first place. =E2=80=9CThis solution does not rely on the pump behaving as it should = =E2=80=9C You should not be flying if your pump or any other part of = the aircraft is not behaving as it should. Too many have died doing = this.=20 Chris Zavatson N91CZ 360std www.N91CZ.net On Wednesday, April 23, 2014 3:04 PM, Wolfgang = wrote: The dump valves in the 360/320 did not "dump" to the reservoir, it only = cross connected the high and low sides of the hydraulic pump. But you = know that. Changing it out for a valve the that does "dump" to the reservoir was = one of my suggestions quite a while back since the pump body already has = ports to accommodate that. =20 Again, forced running of the pump in the appropriate direction = (determined by the gear switch position) when both hi and lo pressure = switches have been tripped rendering the pump inoperable, WILL clear the = problem. That's what a pressure switch monitoring module does, = automatically. This solution works for the 320, 360 and Legacy. =20 This solution does not rely on the pump behaving as it should for the = service life of the pump. I like more than one way of preventing = potential hull damage. =20 This solution can also be implemented by a manual push button switch on = the panel but requires pilot intervention. =20 "if condition are just right, shut the pump down" . . . but once the pulse subsides (miliseconds) that event is over = because the un-extended gear down cylinder volume will absorb that = pulse. . . . unless there is a blockage in the lines . . . then you have other = problems. There is no need to theorize the problem into obscurity. KISS principal = rules. =20 Wolfgang =20 ----- Original Message ----- From: Chris Zavatson To: lml@lancaironline.net Sent: Tuesday, April 22, 2014 7:59 AM Subject: Gear Down...INOP Hitting the dump valve may or may not help the problem. It depends on how much of a temperature increase you incurred. Wolfgang =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 Wolfgang, I suggest a review of the Legacy hydraulic system schematic in the = following document (Legacy Addendum). http://www.n91cz.net/Hydraulics/Lancair%20Hydraulics.pdf You will see that the Legacy has a three-way dump valve that connects = both high and low sides to the reservoir. It will always dump pressure = regardless of temperature rise. Extension failures were more common in the 320/360 and can be resolved = by simply adjusting the low side pressure switch higher (and if needed, = the relief valve also) -see page 10. The higher volume gear pump in the = Legacies reduces the exposure to the failure when using stock pressure = settings. The initial extension sends a pressure pulse through the system and can, = if condition are just right, shut the pump down. The hydraulic system = will think the gear is down and pressurized. This type of failure is = what caught Lorn off-guard and resulted in a gear-up landing. See = attached, the photo of Lorn=EF=BF=BDs pressure gauges after he slid to a = stop. Both gauges are 500 psi +/-. The gear selector is down, the low side pressure switch is open and the = high side pressure switch is closed. The very same condition as when = the gear is fully down and locked. Based on prior descriptions of your = module, it will not detect this condition as a failure and will do = nothing to fix it. Most Legacy pumps have spool return springs which can cause pressure = rise in both sides due to a temperature increase. This is more often an = issue sitting on the ground on a hot parking ramp where the potential = temperature swing is much greater. I recommend removing these springs = per instructions in this link: http://www.n91cz.com/Hydraulics/Pump-Unlock.pdf Chris Zavatson N91CZ 360std www.N91CZ.net -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html --Apple-Mail-27--771492378 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
Chris,
 
Why don't we just agree to = disagree. I believe in=20 redundancy and it looks like you don't. << this is bogus. =  Chris is favoring addressing the original problem. =  Redundancy is having a second copy of a known good design in case = the first copy is physically compromised,  not having a work around = for a design that is known to have a problem.
 
The pressure pulse you're talking = about will=20 subside (glad you agree) and as it does, because the cylinder is only = partially=20 extended, the cylinder will continues to extend, the low switch = will close=20 again, and enable the pump to continue . . . No,=20 the damage has NOT been done.
 
The only way the switch will stay = open (the=20 pressure stays high) is if there is a physical obstruction preventing = the from=20 moving down any further (like when it is full down).
 
Learn to live with the fact that = you're not the=20 only one that knows a thing or two about airplanes.  
 
Wolfgang
 
----- Original Message -----
Sent: Thursday, April 24, 2014 = 8:18=20 AM
Subject: Re: [LML] Fw: Gear=20 Down...INOP

Wolfgang,
Based=20 on your statement, I don=E2=80=99t think you understand this failure=20= mode.
=E2=80=9C. . but once the=20 pulse subsides (miliseconds) that event is over because the = un-extended gear=20 down cylinder volume will absorb that=20 pulse.=E2=80=9D
Yes,=20 the pulse event is over, but the damage is done.  The gear is stuck partially = extended=20 with one pressure switch open and one closed.  Your module WILL NOT clear = this=20 problem.
We=20 have very different approaches to aircraft operation and = maintenance.  I don=E2=80=99= t install gadgets to undo a=20 problem after it occurs.  = I=20 prevent the problem from occurring in the first = place.
=E2=80=9CThi= s solution does not rely on the pump behaving as it should =E2=80=9C   You should not be flying if your pump=20 or any other part of the aircraft is not behaving as it should.  Too many have died doing = this.  =
Chris=20 Zavatson
N91CZ
360std
=
On Wednesday,=20 April 23, 2014 3:04 PM, Wolfgang <Wolfgang@MiCom.net>=20 wrote:
The dump valves in the 360/320 = did not "dump" to=20 the reservoir, it only cross connected the high and low sides of the = hydraulic=20 pump. But you know that.
Changing it out for a valve the = that does=20 "dump" to the reservoir was one of my suggestions quite a while back = since the=20 pump body already has ports to accommodate that.
 
Again, forced running of the pump = in the=20 appropriate direction (determined by the gear switch position) when = both hi=20 and lo pressure switches have been tripped rendering the pump = inoperable, WILL=20 clear the problem. That's what a pressure switch monitoring module = does,=20 automatically. This solution works for the 320, 360 and=20 Legacy.
 
This solution does not rely on = the pump behaving=20 as it should for the service life of the pump. I like more than one = way of=20 preventing potential hull damage.
 
This solution can also be = implemented by a manual=20 push button switch on the panel but requires pilot=20 intervention.
 
"if condition are just right, = shut the pump down"=20
. . . but once the pulse subsides = (miliseconds)=20 that event is over because the un-extended gear down cylinder volume = will=20 absorb that pulse.
. . . unless there is a blockage = in the lines . .=20 . then you have other problems.
There is no need to theorize the = problem into=20 obscurity. KISS principal rules.
 
Wolfgang
 
----- Original Message ----- =
Sent: Tuesday, April 22, 2014 7:59=20 AM
Subject: Gear = Down...INOP

Hitting the=20 dump valve may or may not help the problem.
It depends on how much = of a=20 temperature increase you incurred.
Wolfgang

=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
Wolfgang,
I suggest a review of the Legacy = hydraulic=20 system schematic in the following document (Legacy = Addendum).
http://www.n91cz.net/Hydraulics/Lancair%20Hydraulics.pdf=
You will see that=20 the Legacy has a three-way dump valve that connects both high and low = sides to=20 the reservoir.  It will always dump pressure regardless of = temperature=20 rise.

Extension=20 failures were more common in the 320/360 and can be resolved by = simply=20 adjusting the low side pressure switch higher (and if needed, the = relief valve=20 also) -see page 10.  The higher volume gear pump in the Legacies = reduces=20 the exposure to the failure when using stock pressure settings.
The initial extension = sends a=20 pressure pulse through the system and can, if condition are just = right, shut=20 the pump down.  The hydraulic system will think the gear is down = and=20 pressurized.  This type of failure is what caught Lorn off-guard = and=20 resulted in a gear-up landing. See attached, the photo of Lorn=EF=BF=BDs= pressure=20 gauges after he slid to a stop.  Both gauges are 500 psi +/-.
The gear selector is = down, the=20 low side pressure switch is open and the high side pressure = switch is=20 closed.  The very same condition as when the gear is fully down = and=20 locked.  Based on prior descriptions of your module, it will not = detect=20 this condition as a failure and will do nothing to fix = it.
Most = Legacy pumps=20 have spool return springs which can cause pressure rise in both sides = due to a=20 temperature increase.  This is more often an issue sitting = on the=20 ground on a hot parking ramp where the potential temperature = swing is=20 much greater.  I recommend removing these springs per = instructions in=20 this link:
=

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