Return-Path: Sender: (Marvin Kaye) To: lml Date: Sun, 27 Oct 2002 20:40:58 -0500 Message-ID: X-Original-Return-Path: Received: from imo-r05.mx.aol.com ([152.163.225.101] verified) by logan.com (CommuniGate Pro SMTP 4.0) with ESMTP id 1846300 for lml@lancaironline.net; Sun, 27 Oct 2002 19:52:52 -0500 Received: from Sky2high@aol.com by imo-r05.mx.aol.com (mail_out_v34.13.) id q.ca.13bc1eb4 (30950) for ; Sun, 27 Oct 2002 19:52:41 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Sun, 27 Oct 2002 19:52:40 EST Subject: Re: [LML] LNC 2 hydraulics X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_ca.13bc1eb4.2aede458_boundary" X-Mailer: AOL 8.0 for Windows US sub 230 --part1_ca.13bc1eb4.2aede458_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Ian, Great observations. I have seen the same myself. Try these items: 1. For air bubbles, whilst on jacks, open the dump switch and run the pump for a while to circulate fluid. Then close the valve, activate the up circuit and release the dump valve again. Repeat several times. This should clear any bubbles. 2. The pump itself has a shuttle valve and pressure relief valves. If you are confident that the actuator piston o-rings and cylinders walls are "perfect" and the dump valve is sealing, perhaps the pump has a problem with leak-back. 3. The door valves are actually check-valves (biased to keep the doors open) that are defeated when the gear is up tight. Could these be leaking? 4. Is there any dirt in the system? The pump has filters on the reservoir draw tubes for both up and down but not all the fluid passes thru the system. For example, if you have rebuilt a cylinder, you have noted that the cylinder ends contain blackened fluid, discolored by the deterioration of the o-rings and never passed thru the system except locally. If dirt has gotten in the system, it is possible to reside locally in a cylinder and slowly damage the piston seal. Good luck! Scott Krueger N92EX --part1_ca.13bc1eb4.2aede458_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: 7bit Ian,

Great observations.  I have seen the same myself. 

Try these items:

1. For air bubbles, whilst on jacks, open the dump switch and run the pump for a while to circulate fluid.  Then close the valve, activate the up circuit and release the dump valve again.  Repeat several times.  This should clear any bubbles.

2. The pump itself has a shuttle valve and pressure relief valves.  If you are confident that the actuator piston o-rings and cylinders walls are "perfect" and the dump valve is sealing, perhaps the pump has a problem with leak-back.

3. The door valves are actually check-valves (biased to keep the doors open) that are defeated when the gear is up tight.  Could these be leaking? 

4. Is there any dirt in the system?  The pump has filters on the reservoir draw tubes for both up and down but not all the fluid passes thru the system.  For example, if you have rebuilt a cylinder, you have noted that the cylinder ends contain blackened fluid, discolored by the deterioration of the o-rings and never passed thru the system except locally.  If dirt has gotten in the system, it is possible to reside locally in a cylinder and slowly damage the piston seal.

Good luck!

Scott Krueger
N92EX --part1_ca.13bc1eb4.2aede458_boundary--