X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 25 Feb 2006 00:56:49 -0500 Message-ID: X-Original-Return-Path: Received: from rwcrmhc12.comcast.net ([204.127.192.82] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 997569 for lml@lancaironline.net; Fri, 24 Feb 2006 23:17:32 -0500 Received-SPF: none receiver=logan.com; client-ip=204.127.192.82; envelope-from=rpastusek@htii.com Received: from boblaptop2 (c-69-143-137-39.hsd1.va.comcast.net[69.143.137.39]) by comcast.net (rwcrmhc12) with SMTP id <20060225041644m12001a6kce>; Sat, 25 Feb 2006 04:16:44 +0000 From: "Robert R Pastusek" X-Original-To: "Lancair Mailing List" Subject: RE: [LML] Hydraulic pump X-Original-Date: Fri, 24 Feb 2006 23:17:57 -0500 X-Original-Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0267_01C63998.8BD34990" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 In-Reply-To: Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_0267_01C63998.8BD34990 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Scott Keighan wrote: I've just run my gear up and down on my LIV for the first time and I have a couple of questions. 1. Is the pump supposed to make a very high pitch squeal? If not what would cause it? The sound is almost unbearable. The fluid tank was 3/4 full before priming and was about 1/2 full after. A: The pump is very noisy when operating, although I wouldn't call the "normal" sound a squeal. Other opinions about this? The fluid drop sounds about right, and equates to the volume of the lines and actuators--about one quart. Once the system is filled (be sure to also purge the emergency gear pump circuit by lowering the gear using the hand pump), the fluid level should remain almost constant. 2. The main gear don't go up and down together. The left gear is always first up followed closely by the right. Coming down the left goes down and locked even before the right leaves the wheel well. Should both of the mains be going up and down together. A: There is no "linkage" that will cause the gear to move together. Most I've seen don't move together, but are much closer together than yours. The gear with the lowest operating friction will move first/fastest--both up and down. It sounds like you may have some binding on the right main gear. Based on your description, I'd look closely at the gear door/slider area to see if the door is holding the gear up "unnaturally." One test that you can use to check this is to start with the gear retracted, turn off the master switch or pull the hyd pump circuit breaker, and then cycle the flaps to bleed down the hydraulic pressure. At some point during this process, both mains should "free fall" out of the fuselage to a dangle position. If they don't, select the gear lever to down. If both gear don't fall to the dangle position (will need wheels and brake assemblies installed to sufficiently weight the gear for this test), you have excessive binding in the pivots/doors/actuating cylinders that needs to be corrected. One easy check/adjustment is the pressure plate on top of the rack gear that operates against the drum gear on the main pivot, but your description above points to a hang-up with the gear doors as the most likely culprit. 3. The pump runs for about 10 - 15 seconds after the gear is up. A: This is normal. Operation of the gear uses all the fluid stored (under pressure) in the accumulator, causing the hydraulic system pressure to drop well before the gear gets to its commanded position. This causes the pressure switch to turn the pump on, and it essentially "pumps" the gear into position. Since it takes only about 500 PSI to move the gear to the fully retracted position, the gear gets to the stops before the system pressure is fully restored. As soon as the gear hits the nylon up-stops, fluid starts flowing back into the accumulator, and continues until system pressure reaches the switch shut-off pressure--approximately 900 to 1000 PSI. The system is now restored for operation of the gear (again) or the flaps. 4. The flap accuator is very touchy in the off positon. Wiggling seems to help keeping the flaps up and to stop them from creeping back down. A: The flap actuator is almost certainly not moving to the correct up/off position. This is a common problem, more with the gear actuator than the flap, but it can happen to either. Test this by taking the front panel face off the actuator so you can move the actuator just a bit further up (or down) to see if this corrects the problem. If it does, elongate the slots and you're fixed. One thing that sometimes causes this problem is having the face plate spaced away from the actuator main body, effectively shortening the available "throw" of the levers. If it's not flat against the actuator body, try fixing this first (the thickness of the fiberglass vertical panel between the plate and the actuator body is enough to cause this problem). Any advice would be greatly appreciated. Hope this helps. Bob Pastusek ------=_NextPart_000_0267_01C63998.8BD34990 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Scott = Keighan=20 wrote:
  I've just run my gear up and = down on=20 my  LIV for the first time and I have   a couple of=20 questions.
1.  Is the pump supposed to make = a very high=20 pitch squeal?
If not what would cause it?  The = sound is=20 almost unbearable.
The fluid tank was 3/4 full = before priming=20 and was about 1/2
full after.   
 
A: The pump is very noisy when operating, although I=20 wouldn't call the "normal" sound a squeal. Other opinions = about=20 this? The fluid drop sounds about right, and equates to the volume of = the=20 lines and actuators--about one quart. Once the system is = filled (be=20 sure to also purge the emergency gear pump circuit = by lowering=20 the gear using the hand pump), the fluid level should remain = almost=20 constant. 
 
2. The main gear don't go up and down = together.  The left gear
is always first up followed closely = by the=20 right.  Coming down
the left goes down and locked even = before the=20 right leaves the
wheel well.  Should both of = the mains=20 be going up and down
together. 
 
A: There is no "linkage" that will cause the gear = to move=20 together. Most I've seen don't move together, but are much closer = together=20 than yours. The gear with the lowest operating friction = will move=20 first/fastest--both up and down.  It sounds like you may = have some=20 binding on the right main gear. Based on your description, = I'd look=20 closely at the gear door/slider area to see if the door is holding the = gear up "unnaturally." One test that you can use to = check this=20 is to start with the gear retracted, turn off the master switch = or pull=20 the hyd pump circuit breaker, and then cycle the flaps to = bleed down=20 the hydraulic pressure. At some point during this process, both mains = should=20 "free fall" out of the fuselage to a dangle position. If they don't, = select=20 the gear lever to down. If both gear don't fall to the dangle position = (will=20 need wheels and brake assemblies installed to sufficiently weight the = gear for=20 this test), you have excessive binding in the pivots/doors/actuating=20 cylinders that needs to be corrected. One easy check/adjustment = is the=20 pressure plate on top of the rack gear that operates against the drum = gear on=20 the main pivot, but your description above points to a hang-up with = the gear=20 doors as the most likely culprit.
 
3. The pump runs for about 10 - = 15 seconds=20 after the gear is up. 
 
A: This is normal. Operation of the gear uses all = the fluid=20 stored (under pressure) in the accumulator, causing the hydraulic = system pressure to drop well before the gear gets to its = commanded=20 position. This causes the pressure switch to turn the pump on, and it=20 essentially "pumps" the gear into position. Since it takes only about = 500 PSI=20 to move the gear to the fully retracted position, the gear gets = to the=20 stops before the system pressure is fully restored. As soon = as the=20 gear hits the nylon up-stops, fluid starts flowing back = into=20 the accumulator, and continues until system pressure reaches = the switch=20 shut-off pressure--approximately 900 to 1000 PSI. The system is now restored for operation of the gear = (again) or=20 the flaps.
 
4. The flap accuator is very touchy = in the off=20 positon.  Wiggling
seems to help keeping the flaps up = and to stop=20 them from
creeping back down.  
 
A: The flap actuator is almost certainly not moving to = the correct=20 up/off position. This is a common problem, more with the=20 gear actuator than the flap, but it can happen to = either. Test this=20 by taking the front panel face off the actuator so you can move = the=20 actuator just a bit further up (or down) to see if this corrects = the=20 problem. If it does, elongate the slots and you're fixed. = One thing=20 that sometimes causes this problem is having the face plate = spaced away=20 from the actuator main body, effectively shortening the available = "throw" of=20 the levers. If it's not flat against the actuator body, try fixing = this first=20 (the thickness of the fiberglass vertical panel between the plate and = the=20 actuator body is enough to cause this problem).
 
Any advice would be greatly=20 appreciated. 
 
Hope this helps.  Bob=20 Pastusek
 
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