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CJ Air Leak and Landing Gear problem

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tmckeon79(at)hotmail.com
Guest

Posted: Sun Sep 02, 2012 9:43 am Post subject: CJ Air Leak and Landing Gear problem

Hello,

  

 I just recently imported a CJ-6 from China to the US.  I flew it from CA to FL with no problems other than prehaps a bumpy landing or two.  After arriving at my destination in FL, the next day I went to check on the plane and noticed that the the air had dropped down to about 20 atm.  A few days later (gauge was at 0) I pumped it back up and took the plane for a few laps in the pattern.  The first thing I noticed was that the landing gear would not retract.  The brakes and flaps worked just fine.  After landing I double checked and the rear cockpit had the landing gear handle in the neutral position.  I parked the plane and then returned the next day to have a look at it.  Again the air had dropped to about 20 atm.  One other thing I noticed was that I could hear air leaking out of the "snot valve" on the belly of the plane.  I'm not sure if that is residual from the filter or if it's comming from the main air line.  And I'm not sure how this ties into my landing gear problem.  Oh, and I made sure to tighten the main air valve each time I shut down the plane.

  

 The plane has a total of 25 hours since it's arrival in the United States.  I am also brand new to the CJ and not a mechanic.  I'm hoping I can just replace a check valve somewhere but I don't know where to start.  Any advice would be appreciated.  

  

 Thanks,

 Tom

  

  

 		 	   		  

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wlannon(at)shaw.ca
Guest

Posted: Sun Sep 02, 2012 11:01 am Post subject: CJ Air Leak and Landing Gear problem

Tom;

  

 Assuming you had approx. 40 or more atmâ€™s during the ferry flight the loss  of 20 atmâ€™s  in the OPERATING SYSTEM one day after closing the main valve  is not that unusual.  There is invariably some loss in the  system.   A good tight system should hold some pressure for a week or  more but typically it is more like 2 â€“3 days.  

 When you recharge the system by opening the valve expect to see a loss of 3  or 4 atmâ€™s from the pressure at last shut-down due to re-fill of the  system.  Anything more than that may indicate a leak in the STORAGE  system.

 Operating system leakage can be found and corrected with a lot of time and  patience.

  

 How much pressure on the guage when the gear failed to retract?    I assume from your post that you know the rear gear and flap handles must be in  neutral for front operation.

  

 Walt  

  

  

    

  From: Thomas McKeon (tmckeon79(at)hotmail.com) 

 Sent: Sunday, September 02, 2012 10:41 AM

 To: yak-list(at)matronics.com (yak-list(at)matronics.com) 

 Subject: CJ Air Leak and Landing Gear  problem

  



  Hello,

 

I just recently imported a CJ-6 from China to  the US.  I flew it from CA to FL with no problems other than prehaps a  bumpy landing or two.  After arriving at my destination in FL, the next day  I went to check on the plane and noticed that the the air had dropped down to  about 20 atm.  A few days later (gauge was at 0) I pumped it back up and  took the plane for a few laps in the pattern.  The first thing I noticed  was that the landing gear would not retract.  The brakes and flaps worked  just fine.  After landing I double checked and the rear cockpit had the  landing gear handle in the neutral position.  I parked the plane and then  returned the next day to have a look at it.  Again the air had dropped to  about 20 atm.  One other thing I noticed was that I could hear air leaking  out of the "snot valve" on the belly of the plane.  I'm not sure if that is  residual from the filter or if it's comming from the main air line.  And  I'm not sure how this ties into my landing gear problem.  Oh, and I made  sure to tighten the main air valve each time I shut down the  plane.

 

The plane has a total of 25 hours since it's arrival in the  United States.  I am also brand new to the CJ and not a mechanic.  I'm  hoping I can just replace a check valve somewhere but I don't know where to  start.  Any advice would be appreciated.   

 

Thanks,

Tom

 

 



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k7wx

Joined: 24 May 2010
Posts: 117

Posted: Sun Sep 02, 2012 2:12 pm Post subject: CJ Air Leak and Landing Gear problem

Thomas,



There are two possibilities. I had the exact same problem. If the gear fails to retract, you have a leak in the emergency system. 

First, and most likely is one of the two emergency system check valves on the firewall. See the attached picture for what mine looked like. The other is one, or both of the two emergency air on-off valves in the forward and aft cockpits. You'll have to chase these systematically, but I would start with the emergency system firewall check valves. For me, it turned out that I had two bad firewall emergency system check valves and a bad emergency on-off value in the forward cockpit. 

When you turn off the main air, it's not unusual for the main air pressure gauge to bleed down to zero after several hours. What matters is that when you turn back on the main air that it comes back to 40 ATMs. The emergency system air gauge should stay at 40 ATMs, or more, all the time. 

If you would like some more detailed help, contact me off line and we can work through this. 

Welcome to the CJ-6A. The tired old cliché is that flying a CJ is mostly to discover what needs to be fixed next. 

Good luck with everything,

Warren Hill

N464TW

[img]cid:91D3B3E0-9FCA-40A1-A895-9F272624B154(at)ph.cox.net[/img]

 

On Sep 2, 2012, at 10:41 AM, Thomas McKeon wrote:

 	  Quote: 	
		  Hello,

 

I just recently imported a CJ-6 from China to the US.  I flew it from CA to FL with no problems other than prehaps a bumpy landing or two.  After arriving at my destination in FL, the next day I went to check on the plane and noticed that the the air had dropped down to about 20 atm.  A few days later (gauge was at 0) I pumped it back up and took the plane for a few laps in the pattern.  The first thing I noticed was that the landing gear would not retract.  The brakes and flaps worked just fine.  After landing I double checked and the rear cockpit had the landing gear handle in the neutral position.  I parked the plane and then returned the next day to have a look at it.  Again the air had dropped to about 20 atm.  One other thing I noticed was that I could hear air leaking out of the "snot valve" on the belly of the plane.  I'm not sure if that is residual from the filter or if it's comming from the main air line.  And I'm not sure how this ties into my landing gear problem.  Oh, and I made sure to tighten the main air valve each time I shut down the plane.

 

The plane has a total of 25 hours since it's arrival in the United States.  I am also brand new to the CJ and not a mechanic.  I'm hoping I can just replace a check valve somewhere but I don't know where to start.  Any advice would be appreciated.  

 

Thanks,

Tom

 

 



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JOE HOWSE

Joined: 10 Jan 2006
Posts: 140
Location: DUNCAN BC CANADA

Posted: Sun Sep 02, 2012 3:20 pm Post subject: CJ Air Leak and Landing Gear problem

[quote]    

Had a similar problem once, turned out    to be a bad "O"  ring on the nose gear retraction piston, worked OK on    the jacks but could not overcome the air load in flight, air would bypass and    exhaust through the gear valve,

   Cure was new "O" ring.

   Air leak at snot valve probably corroded drain    valve.

    

   Joe

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_________________
J.C. HOWSE

byronmfox(at)gmail.com
Guest

Posted: Sun Sep 02, 2012 6:27 pm Post subject: CJ Air Leak and Landing Gear problem

I assume the compressor is making good air. 

First, take the slot apart and clean it. Having some garbage in the air system in plane new to the US isn't uncommon.

Second, you may have emergency air bleeding through to the down side. If so, the gear will not come up. Study the pneumatic system diagram and crack a nut on an emergency line to one of the main gear actuators. If air comes out, and it should not, you have a leaking check valve. Pull the check valves on the port firewall adjacent to the descendent filter. Chances are one of the rubber disks in the two valves has failed. It'll be obvious when you open them up. Doug Sapp has a kit which solve the problem. If your can find a recent Red Alert archived on the RPA web, John Long wrote a great article on the subject.

Blitz Fox415-307-2405

On Sep 2, 2012, at 10:41 AM, Thomas McKeon <tmckeon79(at)hotmail.com (tmckeon79(at)hotmail.com)> wrote:



[quote]    Hello,

  

 I just recently imported a CJ-6 from China to the US.  I flew it from CA to FL with no problems other than prehaps a bumpy landing or two.  After arriving at my destination in FL, the next day I went to check on the plane and noticed that the the air had dropped down to about 20 atm.  A few days later (gauge was at 0) I pumped it back up and took the plane for a few laps in the pattern.  The first thing I noticed was that the landing gear would not retract.  The brakes and flaps worked just fine.  After landing I double checked and the rear cockpit had the landing gear handle in the neutral position.  I parked the plane and then returned the next day to have a look at it.  Again the air had dropped to about 20 atm.  One other thing I noticed was that I could hear air leaking out of the "snot valve" on the belly of the plane.  I'm not sure if that is residual from the filter or if it's comming from the main air line.  And I'm not sure how this ties into my landing gear problem.  Oh, and I made sure to tighten the main air valve each time I shut down the plane.

  

 The plane has a total of 25 hours since it's arrival in the United States.  I am also brand new to the CJ and not a mechanic.  I'm hoping I can just replace a check valve somewhere but I don't know where to start.  Any advice would be appreciated.  

  

 Thanks,

 Tom

  

  

 		 	   		  

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