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gear handle air leaking

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jonboede(at)hotmail.com
Guest

Posted: Fri Jun 15, 2007 8:19 am Post subject: gear handle air leaking

I get a small but audible air leak from my front gear handle in the neutral 

and down positions.



However, the leak stops when I put the rear handle in the down position.



So I'm under the impression that my selector in the back seat probably has 

issues (I'm guessing it's gunk'd up).



However, Doug said a while back:



http://www.matronics.com/searching/getmsg_script.cgi?INDEX=37396822?KEYS=qsf-2a?LISTNAME=Yak?HITNUMBER=15?SERIAL=09113229170?SHOWBUTTONS=NO



That it might be the the retract cylinders that need a bit of attention.



How might one determine which of these it is?



Thanks,

Jon

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JBernier(at)dart.org
Guest

Posted: Fri Jun 15, 2007 8:55 am Post subject: gear handle air leaking

Jon

 When the rear gear handle is placed in the up or down position no air is supplied to the front gear selector. It only has that pressure that was left in the line. The air leak is due to the front selector being gunk'd up. This is the good news because the front only has 4 fittings as compared to the rear having 6. After removing the front selector take it apart looking for crud. You will probably find that cleaning it does nothing as it has corrosion. If no corrosion, clean it and apply vacuum grease, or a silicon grease. Place a light coat of grease on the machined surface. The grease is your choice as it will seal the unit, but capture any foreign objects and cause a potential air leak. How clean is your air system? If corroded you can either take it to a machine shop to have the surfaces re-machined or buy it new from Doug. I'd buy it new unless you know a machinist.

 Just my two cents.

 Jim



 	  Quote: 	
		  >> "Jon Boede" <jonboede(at)hotmail.com> 6/15/2007 11:15 AM >>>

--> Yak-List message posted by: "Jon Boede" <jonboede(at)hotmail.com>
	




I get a small but audible air leak from my front gear handle in the neutral 

and down positions.



However, the leak stops when I put the rear handle in the down position.



So I'm under the impression that my selector in the back seat probably has 

issues (I'm guessing it's gunk'd up).



However, Doug said a while back:



http://www.matronics.com/searching/getmsg_script.cgi?INDEX=37396822?KEYS=qsf-2a?LISTNAME=Yak?HITNUMBER=15?SERIAL=09113229170?SHOWBUTTONS=NO



That it might be the the retract cylinders that need a bit of attention.



How might one determine which of these it is?



Thanks,

Jon



http://forums.matronics.com==============





  [quote][b]

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mark.bitterlich(at)navy.m
Guest

Posted: Fri Jun 15, 2007 1:16 pm Post subject: gear handle air leaking

I am not a 52 pneumatic expert.  I am however pretty up to speed on the

50.  Sadly the actuators and layout are different, but close enough that

I would guess that the advice I will give you here will work.  



You might want to put the aircraft on jacks before doing this, just to

be 100$ perfectly safe.  In theory, you should not NEED to, but hey....

I sure would.  



1.  Aircraft on jacks.  

2.  Air off, and depressurize air system. 

3.  Remove one air line at a time that goes to an actuator and is used

to make the landing gear go UP.  Be careful to choose the right one.  

4.  With landing gear selected down, pressurize the system.  

5.  Put your finger over, or your ear near the actuator where you just

removed the UP line.  If there is air leaking out of the actuator

fitting on the actuator itself, then you have found the bad internally

leaking actuator.  

6.  If there is air coming out of the HOSE that you just removed, then

you either removed the wrong hose from the actuator, in which case there

is one HUGE amount of air coming out.... OR.... Your problem is on

ANOTHER actuator.  

7. Assuming you have not screwed up and indeed you have removed the UP

air line from the actuator, put it back on and now move to the next

actuator and remove IT's "UP" air line.  Again, this is the air line

that makes the actuator RETRACT.  Again check to see if the air comes

from the actuator or the hose.  If from actuator, it is bad actuator

leaking internally.  If it is from hose, then put it back on and move to

the next gear actuator.  



Not too difficult really.  Just realize that you have one hose going to

each actuator that puts pressure into it to force them to go down.  You

have another hose hooked to the opposite end of each actuator to make

the actuators move in the opposite direction, in this case UP.  When you

raise or lower the gear, these actuators move.  There are rubber seals

inside to prevent the air from going straight through.  As the actuators

move, they also force air out of the opposite sides of the actuators.

This air is the loud HISS you hear every time you raise and lower the

gear.  Once the gear is either up OR down, this hiss should stop.  If an

actuator is leaking internally, air will tend to go right on through it,

and then travel up the opposite hose, where it is then routed to the

gear handle and vented.  



Thus, if you have a continuous leak at the gear handle, it is usually an

internally leaking actuator.  



The 52, with two gear handles, has come convoluted stuff going on that I

have never studied, and I am sure someone else can explain that to you.

However, the method I have described here will find an internally

leaking actuator pretty quickly.  



Mark Bitterlich





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mark.bitterlich(at)navy.m
Guest

Posted: Fri Jun 15, 2007 1:21 pm Post subject: gear handle air leaking

Thanks for explaining this Jim, I should have read it before I wrote

what I did.  Sorry, but in any case I just learned something about the

52, and also why one local here had a gear collapse on landing.  Anyway,

I would go further to possibly ask this question.  



When you put the gear handle down in the rear seat, very carefully

listen for any air coming out of THAT handle.  If there is no air coming

out of the REAR gear handle in the up or down position, I would

obviously concur with Jim.  If there is air coming out of the REAR gear

handle in the UP or DOWN position, as well as the leak you described in

the front with the rear handle in the middle, I would suspect actuators.

Mark Bitterlich

 



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dsavarese(at)elmore.rr.co
Guest

Posted: Fri Jun 15, 2007 4:51 pm Post subject: gear handle air leaking

In most cases, when you have air leaking out of the front gear handle, it is 

not the gear handle, but one of the landing gear actuators.  As Jim said, 

when you put the rear gear handle in the up or down position you shut off 

the air to the front selector.  Consider the rear gear handle the "master" 

and the front the "slave".  Unfortunately, there is no easy way of 

determining which actuator is causing the leak except by removing the "up" 

side flexible line of the actuator and listening to the gear handle.  By 

removing the easy side, which is the UP side, if that specific actuator is 

leaking though the internal seals from the air supplied by the DOWN side, 

you will feel and hear the air leaking out of the UP fitting on the 

actuator.  It is best to accomplish this troubleshooting with airplane on 

jacks.  BE CAREFUL when removing the flexible lines from both the UP side 

and normal DOWN size of the actuators because inside the flared nut is a 

small flow reducer about the size of a contact lens.  It has a very small 

hole in it about the size of a pin.  The emergency side of the actuator does 

not have a reducer in it.  Both down side flexible lines attach to the 

shuttle valve on the top side of the actuator.



If you need further assistance, don't hesitate to call me.  334-285-2141

Dennis



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mark.bitterlich(at)navy.m
Guest

Posted: Fri Jun 15, 2007 5:11 pm Post subject: gear handle air leaking

Good call on the flow reducing "contact lens" inside of the "up and

down" hose fittings connecting to the actuators.  



I forgot about those in my explanation Dennis and it was a BAD oversight

on my part.  Those little suckers are easy to overlook, easy to roll

away and get lost, and very important for the proper operation of the

gear.  My bad. 



Mark

 



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dsavarese(at)elmore.rr.co
Guest

Posted: Fri Jun 15, 2007 5:54 pm Post subject: gear handle air leaking

No way Mark.  With your contributions to the group you will never be "my 

bad".

Dennis



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