X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 25 Apr 2014 11:52:15 -0400 Message-ID: X-Original-Return-Path: Received: from [107.14.166.228] (HELO cdptpa-oedge-vip.email.rr.com) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTP id 6846691 for lml@lancaironline.net; Fri, 25 Apr 2014 10:44:04 -0400 Received-SPF: none receiver=logan.com; client-ip=107.14.166.228; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: Received: from [74.218.201.50] ([74.218.201.50:1174] helo=lobo) by cdptpa-oedge02 (envelope-from ) (ecelerity 3.5.0.35861 r(Momo-dev:tip)) with ESMTP id 15/C8-01721-0947A535; Fri, 25 Apr 2014 14:43:28 +0000 X-Original-Message-ID: From: "Wolfgang" X-Original-To: "Chris Zavatson" , References: Subject: Re: [LML] Fw: Gear Down...INOP X-Original-Date: Fri, 25 Apr 2014 10:43:20 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0044_01CF6073.2CEF75B0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5512 X-RR-Connecting-IP: 107.14.168.130:25 X-Cloudmark-Score: 0 This is a multi-part message in MIME format. ------=_NextPart_000_0044_01CF6073.2CEF75B0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Chris, Why don't we just agree to disagree. I believe in redundancy and it = looks like you don't.=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. 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). Learn to live with the fact that you're not the only one that knows a = thing or two about airplanes. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 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. 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. 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. This solution can also be implemented by a manual push button switch = on the panel but requires pilot intervention. "if condition are just right, shut the pump down"=20 . . . 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. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 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 ------=_NextPart_000_0044_01CF6073.2CEF75B0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Chris,
 
Why don't we just agree to disagree. I = believe in=20 redundancy and it looks like you don't.
 
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 -----
From:=20 Chris=20 Zavatson
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=99t install = gadgets to undo a=20 problem after it occurs.  = I=20 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=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 www.N91CZ.net
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 -----
From: Chris Zavatson
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<= /A>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:
http://www.n91cz.com/Hydraulics/Pump-Unlock.pdf
=
Chris=20 Zavatson
N91CZ
360std www.N91CZ.net
<= /DIV>
--
For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html<= BR>

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