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unlocks not always locking...

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JL2A

Joined: 07 Apr 2015
Posts: 112
Location: Australia

Posted: Wed Mar 15, 2017 2:46 am Post subject: unlocks not always locking...

Calling the CJ brains trust! Strange problem has just manifested itself, CJ6:



Gear handle in DOWN on the ground. Get airborne, gear handle to UP



Get three red lights, gear handle NEUTRAL.



They all fall down. Sometimes just one, sometimes two.



To fix, I selected handle NEUTRAL while gear is down and locked, then selected DOWN for 3 seconds, then UP. This seemed to give the gear a little more momentum and they get up & locked no problems



Can't replicate it every time, it only sometimes does it... the uplocks don't seem to lock when this happens, even if flying with gear handle in the UP position & three reds, anything over 1.5 G pulls the gear out enough to extinguish the 'gear up' red lights, meaning the locks have rotated enough to press the microswitch, but not far enough to lock.



Needless to say no aerobatics until they are locked...



Have had engineer check uplocks, hook position/angle etc. No audible air leaks.



My only explanation is that when selecting UP, a bit of air is leaking into the DOWN lines at the same time and activating the unlock actuators a little, preventing the uplocks from locking... 



Strange one, any other ideas? Would this be possible? I don't have a great grasp of where all the check valves etc are located and for what reason in the gear system.



Anatole

dsavarese0812(at)bellsout
Guest

Posted: Wed Mar 15, 2017 3:17 am Post subject: unlocks not always locking...

Why do you put the gear handle in neutral in the first place?

Do you know what happens when you put the gear selector in neutral?



Dennis



       From: JL2A <info(at)flyingwarbirds.com.au>

 To: yak-list(at)matronics.com 

 Sent: Wednesday, March 15, 2017 6:46 AM

 Subject: unlocks not always locking...

  

 

--> Yak-List message posted by: "JL2A" <info(at)flyingwarbirds.com.au (info(at)flyingwarbirds.com.au)>



Calling the CJ brains trust! Strange problem has just manifested itself, CJ6:



Gear handle in DOWN on the ground. Get airborne, gear handle to UP



Get three red lights, gear handle NEUTRAL.



They all fall down. Sometimes just one, sometimes two.



To fix, I selected handle NEUTRAL while gear is down and locked, then selected DOWN for 3 seconds, then UP. This seemed to give the gear a little more momentum and they get up & locked no problems



Can't replicate it every time, it only sometimes does it... the unlocks don't seem to lock when this happens, even if flying with gear handle in the UP position, anything over 1.5 G pulls the gear out enough to extinguish the 'gear up' red lights, meaning they are being held by actuators only.



Needless to say no aerobatics until they are locked...



Have had engineer check unlocks, hook position/angle etc. No audible air leaks.



My only explanation is that when selecting UP, a bit of air is leaking into the DOWN lines at the same time and activating the unlock actuators a little, preventing the unlocks from locking... 



Strange one, any other ideas? Would this be possible? I don't have a great grasp of where all the check valves etc are located and for what reason in the gear system.



Anatole





Read this topic online here:



http://forums.matronics.com/viewtopic.pcs.com/Navigator?Yak-List" target="_blank">http://www.matronics.com/Navigsp;              - MATRONICS WEB FORUMS -

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jlpartington(at)reagan.co
Guest

Posted: Wed Mar 15, 2017 3:26 am Post subject: unlocks not always locking...

sounds like all the air is not venting out of the down side 

--

cjpilot710(at)aol.com
Guest

Posted: Wed Mar 15, 2017 4:56 am Post subject: unlocks not always locking...

Some CJ6s have no up locks at all.  For 22 years I've operated mine without them because it came from China like that.  One simply keeps the gear handle "up" the entire flight.  

If you analyze it, it simplifies the system which means less places to leak air.  Also if you lose air pressure for whatever reason, you gear will start to fall down - which is what you want to start happening anyway.  You then simply lock it place with emergency air.  

Leaving the gear handle up all the time does not hurt anything.  Some folks think this wears out the seals, but seals only get wear while moving, not holding the pressure.  Some think it also causes ware on the compressor but the compressor is always "working" and system pressure is regulated by the regulator anyway.  

Your up locks mostly likely need cleaning.  Very simple to and they are not complicated at all.

 

Jim "Pappy" Goolsby



Sent from my iPad from some where on The 3rd rock from the Sun.



On Mar 15, 2017, at 06:24, jlpartington(at)reagan.com (jlpartington(at)reagan.com) wrote:

[quote]

sounds like all the air is not venting out of the down side 

--

dougsappllc(at)gmail.com
Guest

Posted: Wed Mar 15, 2017 7:40 am Post subject: unlocks not always locking...

I agree with Dennis, up is gear up-- down is gear down, leave it alone, do not return it to neutral in flight.



Do you have up locks??Â  A few CJs did not, they relied on air pressure to hold the gear up.Â 

Doug



On Wed, Mar 15, 2017 at 4:15 AM, A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:

 	  Quote: 	
		  Why do you put the gear handle in neutral in the first place?

Do you know what happens when you put the gear selector in neutral?



Dennis



       From: JL2A <info(at)flyingwarbirds.com.au (info(at)flyingwarbirds.com.au)>

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

 Sent: Wednesday, March 15, 2017 6:46 AM

 Subject: unlocks not always locking...

  

 

--> Yak-List message posted by: "JL2A" <info(at)flyingwarbirds.com.au (info(at)flyingwarbirds.com.au)>



Calling the CJ brains trust! Strange problem has just manifested itself, CJ6:



Gear handle in DOWN on the ground. Get airborne, gear handle to UP



Get three red lights, gear handle NEUTRAL.



They all fall down. Sometimes just one, sometimes two.



To fix, I selected handle NEUTRAL while gear is down and locked, then selected DOWN for 3 seconds, then UP. This seemed to give the gear a little more momentum and they get up & locked no problems



Can't replicate it every time, it only sometimes does it... the unlocks don't seem to lock when this happens, even if flying with gear handle in the UP position, anything over 1.5 G pulls the gear out enough to extinguish the 'gear up' red lights, meaning they are being held by actuators only.



Needless to say no aerobatics until they are locked...



Have had engineer check unlocks, hook position/angle etc. No audible air leaks.



My only explanation is that when selecting UP, a bit of air is leaking into the DOWN lines at the same time and activating the unlock actuators a little, preventing the unlocks from locking... 



Strange one, any other ideas? Would this be possible? I don't have a great grasp of where all the check valves etc are located and for what reason in the gear system.



Anatole





Read this topic online here:



http://forums.matronics.com/viewtopic.pcs.com/Navigator?Yak-List" target="_blank">http://www.matronics.com/Navigsp; Â  Â  Â  Â  Â  Â   - MATRONICS WEB FORUMS -

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cjpilot710(at)aol.com
Guest

Posted: Wed Mar 15, 2017 9:22 am Post subject: unlocks not always locking...

PS.  Also the System is not building enough pressure.   the pressure needs to be increased.  Do this at the regulator.

Sent from my iPad from some where on The 3rd rock from the Sun.



On Mar 15, 2017, at 07:53, James Goolsby <cjpilot710(at)aol.com (cjpilot710(at)aol.com)> wrote:

[quote]Some CJ6s have no up locks at all.  For 22 years I've operated mine without them because it came from China like that.  One simply keeps the gear handle "up" the entire flight.  

If you analyze it, it simplifies the system which means less places to leak air.  Also if you lose air pressure for whatever reason, you gear will start to fall down - which is what you want to start happening anyway.  You then simply lock it place with emergency air.  

Leaving the gear handle up all the time does not hurt anything.  Some folks think this wears out the seals, but seals only get wear while moving, not holding the pressure.  Some think it also causes ware on the compressor but the compressor is always "working" and system pressure is regulated by the regulator anyway.  

Your up locks mostly likely need cleaning.  Very simple to and they are not complicated at all.

 

Jim "Pappy" Goolsby



Sent from my iPad from some where on The 3rd rock from the Sun.



On Mar 15, 2017, at 06:24, jlpartington(at)reagan.com (jlpartington(at)reagan.com) wrote:

[quote]

sounds like all the air is not venting out of the down side 

--

wlannon(at)shaw.ca
Guest

Posted: Wed Mar 15, 2017 11:02 am Post subject: unlocks not always locking...

Oh yes!  Gear uplocks; a bit of history here.

  

 Even though the manual does specify the neutral position after gear up I  agree with other posters here and always leave it in the up  position.   There is no logical reason to do otherwise.

  

 All four of the CJâ€™s I imported in 1993 were, like Pappyâ€™s, without  uplocks.  They were early production (1965 to 1969) but clearly came from  the factory with

   uplocks installed and were subsequently removed  in squadron service.   There had to be a reason for that action even  though it did not result in deletion of uplocks in later  production.

  

 The CJ uplock design has a built-in Achilles  Heel.  If any one of the three fails to unlock you will be doing a gear up  landing (hopefully you will put the other two back up first!).   At  gear down selection that action ports air from the Normal (or Emergency) side of  each uplock emergency valve to each uplock release valve and to the gear down side of the actuator.  If the release  valve fails to operate that gear will remain up regardless of the down pressure  in the actuator.

  

 Here I digress a bit!   The early P51  used the same basic Bendix designed undercarriage as the Harvard (and later T6)  aircraft.  Wonderful, fool proof, free-fall to down lock gear!    The uplock was released mechanically with movement of the gear handle to  down.

 But with time, wear, spring failure (and  vibration?) it was possible for the handle to go to down on itâ€™s own.  Just  an annoyance for the Harvard/T6 but fatal  for at least one Mustang.  Very high speed pass and pull up,  gear  falls and wing fails.

 The fix was a simple over-center spring bungee  added to the handle linkage.  Still (IMHO) the best gear ever!

  

 I installed complete new uplock systems on two of  those CJâ€™s including mine.  Two of the new owners were happy without  uplocks but I found it annoying to have red lights flashing every time I pulled  some Gâ€™s.

  

 To those with uplocks installed I highly  recommend a periodic removal and inspection of the release valves and emerg.  valves.

  

 Walt

  

  

  

  

  

  

  

  From: doug sapp (dougsappllc(at)gmail.com) 

 Sent: Wednesday, March 15, 2017 8:36 AM

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

 Subject: Re: unlocks not always  locking...

  



  I agree with Dennis, up is gear up-- down is gear down, leave it  alone, do not return it to neutral in flight.   

 Do you have up locks??  A few CJs did not, they relied on air pressure  to hold the gear up. 

 Doug

  

  

   

 On Wed, Mar 15, 2017 at 4:15 AM, A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:

  	  Quote: 	
		           Why do you    put the gear handle in neutral in the first place?

   Do you know    what happens when you put the gear selector in neutral?



   Dennis



   

   

                  From: JL2A <info(at)flyingwarbirds.com.au (info(at)flyingwarbirds.com.au)>

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

Sent: Wednesday, March 15,    2017 6:46 AM

Subject:    unlocks not always locking...



   

--> Yak-List message    posted by: "JL2A" <info(at)flyingwarbirds.com.au (info(at)flyingwarbirds.com.au)>



Calling the CJ brains    trust! Strange problem has just manifested itself, CJ6:



Gear handle in    DOWN on the ground. Get airborne, gear handle to UP



Get three red    lights, gear handle NEUTRAL.



They all fall down. Sometimes just one,    sometimes two.



To fix, I selected handle NEUTRAL while gear is down and    locked, then selected DOWN for 3 seconds, then UP. This seemed to give the    gear a little more momentum and they get up & locked no    problems



Can't replicate it every time, it only sometimes does it...    the unlocks don't seem to lock when this happens, even if flying with gear    handle in the UP position, anything over 1.5 G pulls the gear out enough to    extinguish the 'gear up' red lights, meaning they are being held by actuators    only.



Needless to say no aerobatics until they are    locked...



Have had engineer check unlocks, hook position/angle etc. No    audible air leaks.



My only explanation is that when selecting UP, a bit    of air is leaking into the DOWN lines at the same time and activating the    unlock actuators a little, preventing the unlocks from locking...    



Strange one, any other ideas? Would this be possible? I don't have a    great grasp of where all the check valves etc are located and for what reason    in the gear system.



Anatole





Read this topic online    here:



http://forums.matronics.com/viewtopic.pcs.com/Navigator?Yak-List"    target="_blank">http://www.matronics.com/Navigsp;                - MATRONICS WEB FORUMS -

=  --> http://www.matronic====================



	


  





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JL2A

Joined: 07 Apr 2015
Posts: 112
Location: Australia

Posted: Wed Mar 15, 2017 1:09 pm Post subject: Re: unlocks not always locking...

I thought this might devolve into a handle position thread!



In the OP I did say that with the handle in UP that the aerobatic G forces pull the gear out enough for the uplock microswitch to turn off.



i.e.. I fly with the handle in UP



Which is why it was interesting to find that when reverting to the gear handle neutral when flying method that the uplocks were occasionally not locking, even though microswitches were clicking.



Regarding the presence of uplocks, not being an engineering expert, I figured they put the uplocks were there so there was less stress on the actuator and retraction assembly while pulling up to 6 Gs? Seems to make sense in a mechanical-sympathy sort of way.



Thanks Jim, I will give them a good clean and see what happens, however seeing as it randomly happens to any of the three it seems unlikely. 



Any merit in the air on the down-side theory? 



PS we also checked the gear doors for contact etc. nothing has shifted

JL2A

Joined: 07 Apr 2015
Posts: 112
Location: Australia

Posted: Wed Mar 15, 2017 1:18 pm Post subject: Re: unlocks not always locking...

 	  Quote: 	
		  Why do you put the gear handle in neutral in the first place?

Do you know what happens when you put the gear selector in neutral?



Dennis



	




The air vents out the gear handle, actuators have atmospheric pressure only in them, and the gear rests on the uplocks?

Ernie

Joined: 11 Jan 2006
Posts: 513

Posted: Wed Mar 15, 2017 1:36 pm Post subject: unlocks not always locking...

If you keep pulling 6 Gs in a CJ, your wings are going to be in the UP position.



On Wed, Mar 15, 2017 at 5:30 PM JL2A <info(at)flyingwarbirds.com.au (info(at)flyingwarbirds.com.au)> wrote:



 	  Quote: 	
		  --> Yak-List message posted by: "JL2A" <info(at)flyingwarbirds.com.au (info(at)flyingwarbirds.com.au)>   > Why do you put the gear handle in neutral in the first place? > Do you know what happens when you put the gear selector in neutral? > > Dennis > >   The air vents out the gear handle, actuators have atmospheric pressure only in them, and the gear rests on the uplocks?     Read this topic online here:  http://forums.matronics.com/viewtopic.php?p=467359#467359       =========== ss="gmail_msg"> _msg"> il_msg"> mail_msg"> List" rel="noreferrer" class="gmail_msg" target="_blank">http://www.matronics.com/Navigator?Yak-List ===========  FORUMS - il_msg"> eferrer" class="gmail_msg" target="_blank">http://forums.matronics.com =========== WIKI - "> errer" class="gmail_msg" target="_blank">http://wiki.matronics.com =========== b Site - Â  Â  Â  Â  Â  -Matt Dralle, List Admin. rel="noreferrer" class="gmail_msg" target="_blank">http://www.matronics.com/contribution ===========

JL2A

Joined: 07 Apr 2015
Posts: 112
Location: Australia

Posted: Wed Mar 15, 2017 6:54 pm Post subject: Re: unlocks not always locking...

 	  Quote: 	
		  If you keep pulling 6 Gs in a CJ, your wings are going to be in the UP position. 	




I was talking from a design point of view. The airframe was designed and rated to 6Gs, so the gear system must be stress tested to handle this over the design life too.



We have a 4G soft limit for all our aeros. Don't really see the need for more.

cjpilot710(at)aol.com
Guest

Posted: Thu Mar 16, 2017 8:47 am Post subject: unlocks not always locking...

While I can understand that the gear lights can come on during positive G  maneuvers, that has not happened to me - with these exceptions.  Low system  pressure (at time I had sprung a leak somewhere) and the most Gs I've ever had  to pull is 5 gs.  (I can get a sloppy loop from cruise with just 2.5  to 3 gs.)  While my acro does not go to the extreme end of the envelope, (I  do my little routine never pulling more than 4 gs).  I never see red lights  AS LONG as I have normal system pressure (50 atmos).

  

 Jim (Pappy) Goolsby

  

  In a message dated 3/15/2017 5:11:54 P.M. Eastern Daylight Time,  info(at)flyingwarbirds.com.au writes:

  	  Quote: 	
		  -->    Yak-List message posted by: "JL2A" <info(at)flyingwarbirds.com.au>



I    thought this might devolve into a handle position thread!



In the OP I    did say that with the handle in UP that the aerobatic G forces pull the gear    out enough for the uplock microswitch to turn off.



i.e.. I fly with the    handle in UP



Which is why it was interesting to find that when    reverting to the gear handle neutral when flying method that the uplocks were    occasionally not locking, even though microswitches were    clicking.



Regarding the presence of uplocks, not being an engineering    expert, I figured they put the uplocks were there so there was less stress on    the actuator and retraction assembly while pulling up to 6 Gs? Seems to make    sense in a mechanical-sympathy sort of way.



Thanks Jim, I will give    them a good clean and see what happens. 



PS we also checked the gear    doors for contact etc. nothing has shifted





Read this topic    online    here:



http://forums.matronics.com/viewtopic.php?p=467358#467358=========================   e  ties  Day  ================================================               - MATRONICS WEB FORUMS  ================================================              - NEW MATRONICS LIST WIKI -_-=                - List Contribution Web Site  sp;                             ===================================================

wlannon(at)shaw.ca
Guest

Posted: Thu Mar 16, 2017 9:43 am Post subject: unlocks not always locking...

The actual reason for gear uplocks is to avoid the scenario of the P51 I 

described earlier.



The original CJ manual does not specify a gear or flap limit but rather a 

maximum circuit speed of 170 Kph (92 Kts).

In the CJ's earliest days in North America a group called Yakkity Yaks 

determined that the gear down/flap down military limits for the NA T6 of

130/109 Kts. would sufffice for the CJ as well.



Any CJ owner who purchased my placard set knows that I thought those numbers 

too high and always recommended 110/90 Kts.  In later years the Civil 

Aviation

Authority in the UK came up with a set of numbers which were almost 

identical.



Walt

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