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Another Air Problem

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BTLYak

Joined: 02 Dec 2015
Posts: 22

Posted: Thu Jun 29, 2017 4:51 am Post subject: Another Air Problem

Yak-52



Start: Good on 3+ air



Air: 3 on take-off



Gear, would not retract.



Recovered on EMG air.



Refilled system to 5+



Start, taxi, TO, 3+ on air, still no gear retraction.



Cleaned and serviced the banjo fitting, soaked check valve in gas overnight. 



System holds air.



Questions:



How long does it take to increase system air pressure during a ground run?



What else could be the problem?

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_________________
"Battle Yak"

dsavarese0812(at)bellsout
Guest

Posted: Thu Jun 29, 2017 5:28 am Post subject: Another Air Problem

If you recently did a gear retraction test, did you bleed off the air by 

squeezing off the brakes until the "fart valve" wentoff? What's 

happening is the shuttle valveballs are either pushed over blocking the 

main air side (that's why the gear won't retract) or a check valve under 

the floor in the rear cockpit is leaking, allowing air pressure when you 

turn on the main air valveto fill the emergency side, thus pushing the 

shuttle valve ballsagain blocking the main side of the shuttle valve.



Until you find and fix the leak in the main system, you may not be able 

to build pressure above what you're already seeing.



I have only seen the following once in 18 years. There are two check 

valve located at the entry to brake reducing valve under the floor in 

the rear cockpit.  One isolates the main side and the other isolates the 

emergency side.  If the check valve that isolates the emergency side 

leaks, it will allow the airflowing through the main side check valve to 

pass over to the emergency side, thus pushing the shuttle valve balls 

over where they block the main air side of the shuttle valve. As long as 

there is pressure on the emergency side of the shuttle valve, you will 

not be able to retract the gear until you eliminate the pressure on the 

emergency side when the main air is turned on.



The only time there should be air pressure on the emergency side is when 

you open the emergency air valveto extend the gear.  Then after you 

extend the gear with the emergency side, you must bleed off the air in 

the system before you reopen the main air valve. When you've bled off 

the air from the emergency extension, then open the main air valve, the 

main air pressure will move the shuttle valve balls back against the 

emergency side of the shuttle valve, thus allowing thegear to be 

retracted normally.



Dennis

A. Dennis Savarese

334-546-8182 (mobile)

www.yak-52.com

Skype - Yakguy1



On 6/29/2017 8:51 AM, BTLYak wrote:

 	  Quote: 	
		   



 Yak-52



 Start: Good on 3+ air



 Air: 3 on take-off



 Gear, would not retract.



 Recovered on EMG air.



 Refilled system to 5+



 Start, taxi, TO, 3+ on air, still no gear retraction.



 Cleaned and serviced the banjo fitting, soaked check valve in gas overnight.



 System holds air.



 Questions:



 How long does it take to increase system air pressure during a ground run?



 What else could be the problem?



 --------

 &quot;Battle Yak&quot;





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=470582#470582

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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hess737(at)aol.com
Guest

Posted: Thu Jun 29, 2017 5:37 am Post subject: Another Air Problem

Emergency air holding gear down



Richard Hess

C 404-964-4885



 	  Quote: 	
		   On Jun 29, 2017, at 7:51 AM, BTLYak <btlyak1(at)gmail.com> wrote:

 

 

 

 Yak-52

 

 Start: Good on 3+ air

 

 Air: 3 on take-off

 

 Gear, would not retract.

 

 Recovered on EMG air.

 

 Refilled system to 5+

 

 Start, taxi, TO, 3+ on air, still no gear retraction.

 

 Cleaned and serviced the banjo fitting, soaked check valve in gas overnight. 

 

 System holds air.

 

 Questions:

 

 How long does it take to increase system air pressure during a ground run?

 

 What else could be the problem?

 

 --------

 &quot;Battle Yak&quot;

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=470582#470582

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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