X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 29 Mar 2012 13:46:13 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-masked.atl.sa.earthlink.net ([209.86.89.68] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTP id 5461203 for lml@lancaironline.net; Thu, 29 Mar 2012 10:48:15 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.68; envelope-from=panelmaker@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=hbmPnv0RWYzjjkjkHDezNt+Wp9kM/61HN+pHx4IjgFe0OT3lXCPGzBv47KdPtKVC; h=Received:From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Mailer:thread-index:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [209.173.71.64] (helo=COMPUTER1) by elasmtp-masked.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1SDGdX-0003rT-O7 for lml@lancaironline.net; Thu, 29 Mar 2012 10:47:39 -0400 From: "Jim Nordin" X-Original-To: "'Lancair Mailing List'" Subject: LNC2 gear diagnosis X-Original-Date: Thu, 29 Mar 2012 09:47:41 -0500 X-Original-Message-ID: <8E99E738607F49E08832EB35B49D0055@COMPUTER1> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0051_01CD0D90.FBF4AB60" X-Mailer: Microsoft Office Outlook 11 thread-index: Ac0NrHmk2qQF5HPRTPe4CM4pG6upSgADgSaw X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-ELNK-Trace: bdfc62829fd2a80cc8ad50643b1069f8239a348a220c260949945e29e80203fbdf901bd31460bc9ba7ce0e8f8d31aa3f350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 209.173.71.64 This is a multi-part message in MIME format. ------=_NextPart_000_0051_01CD0D90.FBF4AB60 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Wouldn=92t you want to look at the pressure switches? If the pump = pressure never exceeds 950 pounds, the pump should never quit running. No? Or can = the switch shut off the power to the pump at 950 pounds? If the pump quits = prior to =B11200 pounds, something is afoul in the switches or the pump = thermally shutdown. Jim =20 _____ =20 From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = Danny Sent: Thursday, March 29, 2012 8:03 AM To: lml@lancaironline.net Subject: [LML] Re: LNC2 gear diagnosis =20 Nope, I took the NW actuator out of the system and installed a gauge on = that pressure line to check. I also played with the dump valve today to see = if a slight movement of the handle made a difference =85 it did. This = weekend I=92ll cap it and see what kind of pressure I get but my guess is that=92s the problem. =20 Danny LNC2-360, 550 hours N 38=B0 43' 25.7" W 77=B0 30' 38.6" =20 From: Sky2high@aol.com [mailto:Sky2high@aol.com]=20 Sent: Wednesday, March 28, 2012 9:06 AM To: lml@lancaironline.net Subject: [LML] Re: LNC2 gear diagnosis =20 Danny, =20 From what you reported it would seem that the nose gear actuator is the = real problem. How about the door actuators? One possible analysis is that = you don't see the 1200 psi because the leak is greater at the higher = pressure and then slows a bit as the pressure goes down or the actuator has its = worse leak at full retraction and less when the piston is not at the full retraction position... =20 Scott Krueger =20 In a message dated 3/27/2012 10:32:25 P.M. Central Daylight Time, danny@n107sd.com writes: If any of you have a suggestion, I=92d appreciate your input. =20 On my last flight home, with no early signs of failure, my gear pump was tripping on about every 2 seconds to maintain pressure. I figured I had = a leaky actuator and would have to rebuild it to resolve this; no big = deal. I found one leaking and figured where there is one, there may be more. = So, I=92m rebuilding all of them. But, before doing so, I put a gauge on = the high pressure side of the pump to see if I had internal leaks there too. = What I found was that my pump will only pressurize to about 950 psi (should be ~1200 psi) and then it bleeds down slowly. I tried to adjust the = pressure switch but it made very little difference. To verify the bleeding, I isolated all actuators out of the system except the nose wheel. I put = the gauge on the high pressure side of the NW actuator line, selected gear = up to pressurize the system, and then quickly crawled under the plane to look = at the gauge. It was bleeding down so fast that by the time I got down = there to look at it (~2 sec.), it had already lost about 200 psi and then bled down the rest of the way in about 7 more seconds. So, and here=92s the question, do I have a faulty gear dump valve, a leaky pump, or both? =20 =20 Danny LNC2-360, ~550 hours N 38=B0 43' 25.7" W 77=B0 30' 38.6" =20 ------=_NextPart_000_0051_01CD0D90.FBF4AB60 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

Wouldn=92t you want to look at the = pressure switches? If the pump pressure never exceeds 950 pounds, the pump should = never quit running. No? Or can the switch shut off the power to the pump at = 950 pounds? If the pump quits prior to =B11200 pounds, something is afoul in the = switches or the pump thermally shutdown.
Jim

 

From: = Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Danny
Sent: Thursday, March 29, = 2012 8:03 AM
To: = lml@lancaironline.net
Subject: [LML] Re: LNC2 = gear diagnosis

 

Nope, I took the NW actuator = out of the system and installed a gauge on that pressure line to check.=A0 I also = played with the dump valve today to see if a slight movement of the handle made = a difference =85 it did.=A0 This weekend I=92ll cap it and see what kind = of pressure I get but my guess is that=92s the problem.

 

Danny

LNC2-360, 550 hours

N 38=B0 43' 25.7"

W 77=B0 30' 38.6"

 

From: = Sky2high@aol.com [mailto:Sky2high@aol.com]
Sent: Wednesday, March = 28, 2012 9:06 AM
To: = lml@lancaironline.net
Subject: [LML] Re: LNC2 = gear diagnosis

 

Danny,

 

From what you reported it would = seem that the nose gear actuator is the real problem.  How about the door actuators?  One possible analysis is that you don't see the 1200 = psi because the leak is greater at the higher pressure and then slows a bit = as the pressure goes down or the actuator has its worse leak at full retraction = and less when the piston is not at the full retraction = position...

 

Scott Krueger

 

In a message dated 3/27/2012 = 10:32:25 P.M. Central Daylight Time, danny@n107sd.com writes:

If any of you have a suggestion, = I=92d appreciate your input.

 

On my last flight home, with no = early signs of failure, my gear pump was tripping on about every 2 seconds to maintain pressure.=A0 I figured I had a leaky actuator and would have to = rebuild it to resolve this; no big deal.=A0 I found one leaking and figured = where there is one, there may be more.=A0 So, I=92m rebuilding all of them.=A0 But, = before doing so, I put a gauge on the high pressure side of the pump to see if I had internal leaks there too.=A0 What I found was that my pump will only = pressurize to about 950 psi (should be ~1200 psi) and then it bleeds down = slowly.=A0 I tried to adjust the pressure switch but it made very little difference.=A0 To = verify the bleeding, I isolated all actuators out of the system except the nose wheel.=A0 I put the gauge on the high pressure side of the NW actuator = line, selected gear up to pressurize the system, and then quickly crawled = under the plane to look at the gauge.=A0 It was bleeding down so fast that by the = time I got down there to look at it (~2 sec.), it had already lost about 200 = psi and then bled down the rest of the way in about 7 more seconds.=A0 So, and = here=92s the question, do I have a faulty gear dump valve, a leaky pump, or = both?

 

 

Danny

LNC2-360, ~550 = hours

N 38=B0 43' = 25.7"

W 77=B0 30' = 38.6"

 

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