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gear problem

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talew(at)bellsouth.net
Guest

Posted: Mon Jan 30, 2006 7:34 pm Post subject: gear problem

Has anyone seen this problem before?

 The left main gear will not retract unless I go to  neutral then pull the handle up.

 I have checked all of the shuttle valves in the  left gear system.They

 test OK. The  actuator will extend at  45 psi when out of the aircraft with no  leaks. I changed the check valve on the firewall below the air filter that  was corroded. It needed to be changed but it was not a fix.I am running out of ideas.

 I am thinking I have a blockage in the return of  the extend pressure,however I haven't found it yet.

 Terry Lewis

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wlannon(at)cablerocket.co
Guest

Posted: Mon Jan 30, 2006 10:51 pm Post subject: gear problem

Terry;

  

 Is this a CJ or 52?.

 I assume a CJ but this part of the system is  probably the same. The usual reason for this  problem is air pressure  in the down side of the retract cylinder.

 Could be internal leakage in the check valve (on  the firewall) that stops the normal system from pressurizing the emerg.  system. Usually a corroded valve and spring. But generally with this  problem none of the gear would retract.

 If that happens the pressure in the emergency  system goes directly (not through the gear control valves) to the down side  of the actuators and will be trapped there.

 Easy to test.Remove the line to the emerg side,  pressurize the main system and check for air leakage at the emerg.  port,

 Also could be a failed seal inside the retract  cylinder. With it on the bench and in the gear up position is there  any leakage from the down port with pressure in the up  side.

  

 Also the possibility of a failing uplock release  valve or it's associated emergency diverter valve.

  

 Good luck;

 Walt 

  

 [quote]   ---

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cjpilot710(at)aol.com
Guest

Posted: Tue Jan 31, 2006 5:07 am Post subject: gear problem

Terry,

  

 Walt makes some good  points.  But I would check your gear handle valve.  Me thinks, that  with the gear working AFTER you've put the handle in neutral (dumping all  pressure), that you may have a problem there in that the face of the valve may  be scratched or corroded allowing pressure to cross even if the valve moved to  the up side.

  

 Also might want to  recheck that emergency shuttle valve.  If you can sake it and hear the  valve spring back and forth, it's good.  If that valve is not seated just a  little bit, the gear will not re track.

  

 Jim "Pappy"  Goolsby

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gus.fraser(at)gs.com
Guest

Posted: Tue Jan 31, 2006 5:33 am Post subject: gear problem

Emergency shuttle valve  gets my vote, I had exactly the same issue and that was it.

  

 Gus



  	  Quote: 	
		           From: owner-yak-list-server(at)matronics.com    [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of    cjpilot710(at)aol.com

Sent: Tuesday, January 31, 2006 8:04    AM

To: yak-list(at)matronics.com

Subject: Re: gear    problem

   

   Terry,

    

   Walt makes some good    points.  But I would check your gear handle valve.  Me thinks, that    with the gear working AFTER you've put the handle in neutral (dumping all    pressure), that you may have a problem there in that the face of the valve may    be scratched or corroded allowing pressure to cross even if the valve moved to    the up side.

    

   Also might want to    recheck that emergency shuttle valve.  If you can sake it and hear the    valve spring back and forth, it's good.  If that valve is not seated just    a little bit, the gear will not re track.

    

   Jim "Pappy"    Goolsby

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rvfltd(at)televar.com
Guest

Posted: Wed Feb 01, 2006 5:38 pm Post subject: gear problem

Terry,  I am sure it is your diverter valves, somehow air is leaking into the back side  of the system.  If someone has been messing with your emergency air cock  this will also cause the same or worse problem but that is easily fixed by  bleeding the air off the system.  

  

 If you  require them, I have all the small parts necessary to overhaul the shuttle  valves, or new valves if you want to go that way.  Be VERY careful when  taking off the end cap as they are normally really tight and take a bunch of  torque to break them loose.  Squeeze it to tight in the vise and you  will oblong the housing and the shuttle will not work properly, if it's too  loose it will spin in the vise and will "two block" the center fitting  and break it off.  All is not lost as I have them also, but just go slowly  and you won't have a problem.   

  

 Another word of caution, check your desiccant air dryer, if you diverter  valves are nasty you most likely have a problem in you dryer.  Give me a  call at 509-826-4610 if you have any questions. 

  

 Good  luck

  

 

Always Yakin,

Doug Sapp   [quote]   --

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talew(at)bellsouth.net
Guest

Posted: Thu Feb 02, 2006 9:07 am Post subject: gear problem

First let me thank the folks who offered  advise.

  I did find that I needed the check valve on the firewall but that didn't fix the  problem. All the other check valves  and shuttle valves were fine.

 What I found after blowing out the lines to the  rear gear valve was that I had a restrictor in the left gear line but no  restrictor in the right gear line.

 This restrictor had hole of about .0030 in and  could have been blocked by a grain of sand or such. I removed the restrictor and  the problem is gone!

 Again, Thanks for the help.

 Terry Lewis

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dsavarese(at)elmore.rr.co
Guest

Posted: Thu Feb 02, 2006 12:21 pm Post subject: gear problem

The restrictors are used to reduce the flow, not the  pressure.  Removing the restrictor only causes the landing gear to move way  to rapidly, much like blowing the gear down with the emergency system, which has  no restrictors in the lines.  My suggestion is to put them back in  place.  FWIW.

 Dennis

  

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