Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Sun, 31 Oct 2004 00:18:16 -0400 Message-ID: X-Original-Return-Path: Received: from [206.246.194.60] (HELO visi.net) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 492625 for lml@lancaironline.net; Sat, 30 Oct 2004 23:59:50 -0400 Received-SPF: none receiver=logan.com; client-ip=206.246.194.60; envelope-from=rpastusek@htii.com X-Virus-Scanner: ClamAV Received: from [69.143.104.75] (HELO cp172883-b.arlngt01.va.comcast.net) by visi.net (CommuniGate Pro SMTP 4.2) with SMTP id 34726971 for lml@lancaironline.net; Sat, 30 Oct 2004 23:56:48 -0400 Reply-To: From: "Bob Pastusek" X-Original-To: "Lancair Mailing List" Subject: RE: [LML] L-IV Hydraulic Problem X-Original-Date: Sat, 30 Oct 2004 23:56:10 -0400 X-Original-Message-ID: <039901c4befd$8f1a8620$6601a8c0@cp172883-b.arlngt01.va.comcast.net> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_039A_01C4BEDC.0808E620" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook 8.5, Build 4.71.2173.0 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_039A_01C4BEDC.0808E620 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Anyone run into this problem ?? My hydraulic pump has started to run continuously at 900 PSI instead of shutting off at 1100 PSI billhogarty@direcway.com Bill, Two possibilities: You have an internal leak in the hydraulic system--fluid is passing from the high pressure side to the low side, OR--you have an internal pump failure. The pump failure is the least likely if it's been working normally, but if you can get to your manifold easily, it may be the easiest/quickest to test? Simply disconnect and plug the manifold outputs to the gear and flap control valves (two lines). You'll need to keep the pressure sensor switch connected, and the reservoir doesn't matter. Power the system up and see if it pressurizes and shuts off (should do this almost immediately). If the pump continues to run, pull it and check the internal bypass built into the pump first. If it's not leaking, probably time to send the pump for repair/replacement. If the pump shuts down at 1000-1100 psi, the pump is OK. You'll need to CAREFULLY bleed the pressure and reconnect either the gear or flap feed line. (There will be lots of pressure in the system, and you can't bleed it "normally" by cycling the flaps). For this reason, I'd connect and test the flap circuit for an internal leak as the next step... The leak can be either in the flap or the gear circuit, and the easiest of the culprits to check is the gear/flap actuator valve itself. If either are in an "intermediate" position, they will bypass fluid and cause this problem. Be sure both gear and flap levers are moving all the way to the designated position. (Although I recommended you start with the pump test, I'd probably check these possibilities first as the easiest thing to assess-even a very small mis positioning is enough to bypass fluid at 1000 psi.) Another possibility is a failure of the internal seals in the valve body, but a failure within one of the actuators is more likely. You can assess both as follows. Actuate the pump with the flap circuit (only) reconnected to the manifold. If the pump shuts off normally with the flap connection restored, you've isolated the problem to the gear system. If the pump continues to run with the flap circuit connected to the manifold, disconnect and plug the flap actuator input line, either at the valve body exit, or under the rear seat. Test again. If the pump runs, the valve body is at fault--flap side. If it doesn't, the flap actuator cylinder is at fault. Based on ease of access, and having passed the gear lever position verification above, I'd probably start by disconnecting and plugging each of the gear actuator lines in turn, but if you can get to it easily, plugging the gear actuator line where it comes from the manifold (before it tees off to the nose gear) will verify that you don't have an internal gear valve leak. In any case, if you haven't found the problem by now, you're probably facing a gear actuator internal leak; it's only a matter of isolating each and testing until you find the bad one... If you get through all three and didn't isolate a bad one, go look for an internal leak in the gear actuator body. Bottom line: Lots of work, but I've tried to organize the search in order of ease of test and most likely. If you're not dumping your fluid overboard, the system is either leaking internally, or the pump just can't get to the required 1100 psi any more... Good luck, and let me know what you found--these are always "fun." Bob Pastusek ------=_NextPart_000_039A_01C4BEDC.0808E620 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Anyone run into this problem = ?? 
 My=20 hydraulic  pump has started to run continuously at 900 PSI = instead of=20 shutting off at 1100 PSI 
 billhogarty@direcway.com 
 
Bill, 
Two=20 possibilities: You have an internal leak in the hydraulic = system--fluid is=20 passing from the high pressure side to the low side, OR--you = have an=20 internal pump failure.
 
The=20 pump failure is the least likely if it's been working normally, but if = you can=20 get to your manifold easily, it may be the easiest/quickest to test? = Simply=20 disconnect and plug the manifold outputs to the gear and flap control = valves=20 (two lines). You'll need to keep the pressure sensor switch = connected, and=20 the reservoir doesn't matter. Power the system up and see if it = pressurizes=20 and shuts off (should do this almost immediately). If the pump continues = to run,=20 pull it and check the internal bypass built into the = pump first. If=20 it's not leaking, probably time to send the pump for=20 repair/replacement.
 
If the=20 pump shuts down at 1000-1100 psi, the pump is OK. You'll need to = CAREFULLY=20 bleed the pressure and reconnect either the gear or flap feed line. = (There will=20 be lots of pressure in the system, and you can't bleed it "normally" by = cycling=20 the flaps). For this reason, I'd connect and test the flap circuit for = an=20 internal leak as the next step...
 
The=20 leak can be either in the flap or the gear circuit, and the easiest of=20 the culprits to check is the gear/flap actuator valve itself. If = either are=20 in an "intermediate" position, they will bypass fluid and cause this = problem. Be=20 sure both gear and flap levers are moving all the way to the designated=20 position. (Although I recommended you start with the pump test, I'd = probably=20 check these possibilities first as the easiest thing to assess-even a = very small=20 mis positioning is enough to bypass fluid at 1000 = psi.)
 
Another possibility is a failure of the = internal seals=20 in the valve body, but a failure within one of the actuators is = more=20 likely. You can assess both as follows. Actuate the pump with the flap = circuit=20 (only) reconnected to the manifold. If the pump shuts off normally with = the flap=20 connection restored, you've isolated the problem to the gear system. If = the pump=20 continues to run with the flap circuit connected to the manifold, = disconnect and=20 plug the flap actuator input line, either at the valve body exit, or = under the=20 rear seat. Test again. If the pump runs, the valve body is at = fault--flap side.=20 If it doesn't, the flap actuator cylinder is at = fault.
 
Based=20 on ease of access, and having passed the gear lever position = verification above,=20 I'd probably start by disconnecting and plugging each of the gear = actuator lines=20 in turn, but if you can get to it easily, plugging the gear actuator = line where=20 it comes from the manifold (before it tees off to the nose gear) will = verify=20 that you don't have an internal gear valve leak. In any case, if you = haven't=20 found the problem by now, you're probably facing a gear actuator = internal=20 leak; it's only a matter of isolating each and testing until you find = the bad=20 one... If you get through all three and didn't isolate a bad one, go = look for an=20 internal leak in the gear actuator body.
 
Bottom=20 line: Lots of work, but I've tried to organize the search in order of = ease of=20 test and most likely. If you're not dumping your fluid overboard, = the=20 system is either leaking internally, or the pump just can't get to = the=20 required 1100 psi any more...

Good luck, and let = me know what=20 you found--these are always "fun."
 
Bob=20 Pastusek
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