X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: Date: Fri, 06 Nov 2009 00:35:11 -0500 Message-ID: X-Original-Return-Path: Received: from imr-mb02.mx.aol.com ([64.12.207.163] verified) by logan.com (CommuniGate Pro SMTP 5.3c1) with ESMTP id 3950481 for lml@lancaironline.net; Thu, 05 Nov 2009 23:05:28 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.207.163; envelope-from=Sky2high@aol.com Received: from imo-da01.mx.aol.com (imo-da01.mx.aol.com [205.188.169.199]) by imr-mb02.mx.aol.com (8.14.1/8.14.1) with ESMTP id nA644jn0007807 for ; Thu, 5 Nov 2009 23:04:45 -0500 Received: from Sky2high@aol.com by imo-da01.mx.aol.com (mail_out_v42.5.) id q.d2c.541d9f02 (14457) for ; Thu, 5 Nov 2009 23:04:41 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Thu, 5 Nov 2009 23:00:17 EST Subject: Re: [LML] 360 landing gear X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1257480017" X-Mailer: AOL 9.1 sub 5006 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com -------------------------------1257480017 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Don, Let's think about that. What could have caused the pressure switch contacts to fuse in the closed position? Was it an incredible surge from a power inrush to the intermittent relay coil, bouncing switch contacts affected by a surge from the collapsing coil at its release or what? Of course, contact resistance from carbon build-up can eventually result in enough arcing to possibly fuse the contacts. I'm sure a diode on the relay coil would ameliorate everything but dirty contact arcing. My experience with a test pump motor was that it would not run when power is applied to both sides of the pump. I cannot understand how the gear switch in the down position can shunt power over to the up relay even if the up pressure switch contacts are fused - I can see how the pump would run continuously if the gear up switch was selected and the fused pressure switch would not shut the relay off when the pressure target was reached - that is the pump would continue to run and the pressure would be limited to that set in the pump up pressure relief valve. Scott Krueger In a message dated 11/5/2009 8:22:13 P.M. Central Standard Time, don-ryan@sbcglobal.net writes: Similar incident, landing gear comes up as I am landing!!! Found the high pressure switch fused closed! Added diodes to protest the pressure switches and ignition. Earlier, the same thing happened to the ig relay, fused closed!! -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html -------------------------------1257480017 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Don,
 
Let's think about that.  What could have caused the pressure swi= tch=20 contacts to fuse in the closed position?  Was it an incredible surge= from a=20 power inrush to the intermittent relay coil, bouncing switch contacts affe= cted=20 by a surge from the collapsing coil at its release or what?  Of cours= e,=20 contact resistance from carbon build-up can eventually result in enough ar= cing=20 to possibly fuse the contacts.  I'm sure a diode on the rel= ay=20 coil would ameliorate everything but dirty contact arcing. 
 
My experience with a test pump motor was that it would not run= when=20 power is applied to both sides of the pump. 
 
I cannot understand how the gear switch in the down position can shun= t=20 power over to the up relay even if the up pressure switch contacts are fus= ed - I=20 can see how the pump would run continuously if the gear up=20 switch was selected and the fused pressure switch would not shut= the=20 relay off when the pressure target was reached - that is the pump wou= ld=20 continue to run and the pressure would be limited to that set in the= pump=20 up pressure relief valve.
 
Scott Krueger
 
In a message dated 11/5/2009 8:22:13 P.M. Central Standard Time,=20 don-ryan@sbcglobal.net writes:
Similar=20 incident, landing gear comes up as I am landing!!! Found the high
pr= essure=20 switch fused closed! Added diodes to protest the pressure switches
a= nd=20 ignition. Earlier, the same thing happened to the ig relay, fused
cl= osed!!=20


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