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MF'ing air system! Yak-50
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dsavarese(at)elmore.rr.co
Guest

Posted: Thu Sep 13, 2007 8:30 am Post subject: MF'ing air system! Yak-50

Tim,



---

viperdoc(at)mindspring.co
Guest

Posted: Thu Sep 13, 2007 8:39 am Post subject: MF'ing air system! Yak-50

Neither am I, Tim. Time to put it back on the jacks and swing the gear

again. It may be as simple as a crush washer or as major as a leak in one of

your air lines. What is the pressure in the system at the time you drop the

gear. At least on the jacks you can listen for air escaping from the system.

A ultrasonic air leak testor would help a bunch in tracking down a leak in

the lines or the fittings.

My 2 cents,

Doc



--

dsavarese(at)elmore.rr.co
Guest

Posted: Thu Sep 13, 2007 8:40 am Post subject: MF'ing air system! Yak-50

Tim,

Why not put the airplane back on the jacks and do another gear retraction 

test to see if there is a leak somewhere.  You said all was normal right 

after overhauling the actuators and doing the gear retraction test.  Then 

after you flew it, the gear used up 20+ ATM during retraction in flight. 

That is definitely abnormal.  I suspect there is a leak around the seals in 

one or both of the overhauled actuators or one of the flexible hoses going 

to the UP side of the actuator is either loose or split.



If an actuator is leaking around the internal seals, the air will exhaust 

for a long period of time through the gear handle.  You typically can't hear 

that in flight.  But I'll bet you can on the ground.  Normal operation 

should use about 5-7 ATM's to retract the gear.

Dennis

---

dsavarese(at)elmore.rr.co
Guest

Posted: Thu Sep 13, 2007 8:48 am Post subject: MF'ing air system! Yak-50

Tim,

Another thought.  Did you know the internal condition of the 52 air tank you 

installed in your airplane?  If there was any junk, rust or corrosion inside 

that air tank and it exited the tank after the first couple of uses, that 

could have easily caused one of the seals in an actuator to go T.U.

Dennis



---

brian-1927(at)lloyd.com
Guest

Posted: Thu Sep 13, 2007 9:18 am Post subject: MF'ing air system! Yak-50

On Sep 13, 2007, at 9:38 AM, A. Dennis Savarese wrote:



 	  Quote: 	
		   Normal operation should use about 5-7 ATM's to retract the gear.


	


And if he has replaced the -50 tank with a tank from a -52 the  

pressure drop will be even less as there is more volume in the system.



Hmm, if something blocked access to the tank then system volume would  

be really low and the volume change in the actuators would make for a  

big pressure drop.



--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry



PGP key ID:          12095C52A32A1B6C

PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Thu Sep 13, 2007 9:43 am Post subject: Re: MF'ing air system! Yak-50

Brian,



Can you break that down...I think I know what you are saying...but!

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Thu Sep 13, 2007 9:53 am Post subject: Re: MF'ing air system! Yak-50

The problem exist extending AND retracting the gear. 



System pressure of about 35-45 ATM before takeoff. Gear retraction, I lose about 20 ATM. Compressor works as advertised and hits the 50 mark pretty quickly. Time to drop the gear, system pressure of 50 ATM or so. Handle down, again, big drop in pressure. So the pressure drop is both up and down. 



The bottle came from Steve Culp...I assume it was unused or nearly so. It was NOT out of another airplane....to the best of my knowledge. 



Like I said before, all was well UNTIL my primary bottle died. The gear would come up and go down with a nice thud. New bigger bottle, slow gear and pressure drop. Are there some physics involved here? 



Thanks for all your input. I will check what you guys have mentioned...

brian-1927(at)lloyd.com
Guest

Posted: Thu Sep 13, 2007 10:59 am Post subject: MF'ing air system! Yak-50

On Sep 13, 2007, at 10:43 AM, Tim Gagnon wrote:



 	  Quote: 	
		   



 Brian,



 Can you break that down...I think I know what you are saying...but!


	


The system has volume to hold all the air. Every line, hose, and  

valve has a small but finite volume. All that taken together is the  

volume of the system with the exception of the storage tank.  

Typically the volume of the storage tank is several times that of the  

rest of the system.



Just for the sake of argument, let's say that the volume of the  

system exclusive of the storage tank is 1/2L and that the volume  

change of the actuators is 1/2L. If the storage tanks was somehow cut  

off from the rest of the system then extending or retracting the gear  

would cause a temporary doubling of the volume so that pressure drop  

would be 1/2 of the total pressure. That would easily explain a huge  

pressure change. Also, the pressure change would slow down the rate  

of extension or retraction. Eventually you get down to the point  

where the compressor (slowly) makes up for the difference.



So I would check the lines, valves, and check-valves going to the  

storage tank as well. If something somehow blocked the path from the  

rest of the system to/from the storage tank you would see the  

symptoms you are describing.



OTOH, leaky seals are a more likely explanation. The other advice you  

have received is good and you should act on that too.



--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry



PGP key ID:          12095C52A32A1B6C

PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C

mark.bitterlich(at)navy.m
Guest

Posted: Thu Sep 13, 2007 11:52 am Post subject: MF'ing air system! Yak-50

Your additional wording in answer to Brian's comments allows me to agree

completely with what Brian was telling you Tim.  



The big clue is when you said that there is a 20 ATM drop in pressure

and then you said: "The compressor works as advertised and hits the 50

ATM mark pretty quickly." 



Here's the reason: 



There is no stock compressor on a M-14 that makes up that kind of loss

quickly.  Just does not happen.  Of course I am guessing by quickly,

that you mean a few minutes or even less.  That indicates that you have

a VOLUME issue and not a PRESSURE issue.  Bear with me here.  



Just think what would happen if you had a perfectly working system, and

then put a RESTRICTION IN THE LINE between the bottle and the gear

handle.  Remember too that just like in electronics, if there is no

current flow, there is no drop in voltage.  Same with this.  If you have

no movement of air in the system, even with a HUGE restriction in the

line, the pressure will be the same everywhere along the line.  UNTIL

you raise or lower the gear, and THEN you have MOVEMENT.  



At that point, (gear going up or going down) you will need the FLOW of

air to make things happen.  If there is a big restriction in the line,

the pressure will drop quickly, because the restriction keeps the air

being able to flow through the line in order to make up for the loss in

pressure. Thus like Brian said, you have a air VOLUME issue. Once the

gear is either fully down or fully up, the flow of air is greatly

reduced, and the pressure will then build rather rapidly because it is

still IN THE TANK and is not having to be built back up by the

compressor, it just has to make it past the restriction and

re-pressurize the air lines and fittings.   



Since the gage in the 50 is connected right next to the landing gear

handle, and since the behavior of the landing gear is being mirrored by

the indications on the pressure gage, this gives solid basis for

pointing to an area from the bottle TO the pressure gage // gear handle.

Since this problem started right after you added the new bottle, then

the logical place to look is from the bottle outlet itself, to the lines

running to where they attach to the OLD lines.  



The simple answer:  You don't have a leak.  You have a restriction in

one of the air lines going from the bottle TO the cockpit gage // gear

handle area.  



Mark Bitterlich 

N50YK

--

Scooter

Joined: 10 Jan 2006
Posts: 155

Posted: Thu Sep 13, 2007 12:38 pm Post subject: Re: MF'ing air system! Yak-50

If I follow the logic here correctly then you could check for either a leak or a restriction by cycling the gear on the ground.  Put it up, verify the 20 drop on the gauge then if the pressure slowly creeps up to where it normally would be then you have a restriction.

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Thu Sep 13, 2007 1:11 pm Post subject: Re: MF'ing air system! Yak-50

Anyone have a schematic for the -50 air system or does one even exist?

mark.bitterlich(at)navy.m
Guest

Posted: Thu Sep 13, 2007 1:28 pm Post subject: MF'ing air system! Yak-50

Got one in my head Tim!  



Suggestion:  Go get a high pressure bottle... Scuba, nitrogen, whatever

you can lay your hands on.  Put aircraft on jacks.  Hook bottle up right

at the blow off pressure relief valve on the left side above snot valve.

Adjust pressure to just where the pop-off valve starts to vent pressure.

Check your landing gear operation.  Speed, force, etc.  Then hook it

back to the original aircraft tank (your new one).  See if there is a

difference.  My bet is that you will see a HUGE change.  With the

external bottle it will work as it used to. 



Move the external pressure source back towards your new bottle one step

at a time to find the restriction.  



Mark

 



--

mark.bitterlich(at)navy.m
Guest

Posted: Thu Sep 13, 2007 1:46 pm Post subject: MF'ing air system! Yak-50

That is absolutely correct.  However, if the engine is not running

(which it will not be on jacks), then if there is a restriction, the

pressure should drop dramatically when the gear is cycled, the gear will

move more slowly than normal, the pressure gage will reach a LOW READING

and then once the gear has stopped moving, THE PRESSURE GAGE WILL

INCREASE BY SOME DEGREE.  It will not go all the way back to where it

was of course, air has been used.  However, if it goes to a low point,

then the gear stops moving, and then it creeps back up to a higher

value, there is no question ... There is a restriction. 



Mark

 



--

brian-1927(at)lloyd.com
Guest

Posted: Thu Sep 13, 2007 2:37 pm Post subject: MF'ing air system! Yak-50

On Sep 13, 2007, at 10:53 AM, Tim Gagnon wrote:



 	  Quote: 	
		   Like I said before, all was well UNTIL my primary bottle died. The  

 gear would come up and go down with a nice thud. New bigger bottle,  

 slow gear and pressure drop. Are there some physics involved here?


	


Look for crud blocking the line to the bottle and keeping it from  

feeding air to the rest of the system.

--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry



PGP key ID:          12095C52A32A1B6C

PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Thu Sep 13, 2007 4:03 pm Post subject: Re: MF'ing air system! Yak-50

Let me ask this..would a smaller diameter line than original cause enough a restriction to explain the problems I am having.

cjpilot710(at)aol.com
Guest

Posted: Thu Sep 13, 2007 4:39 pm Post subject: MF'ing air system! Yak-50

In a message dated 9/13/2007 6:38:05 P.M. Eastern Daylight Time,  brian-1927(at)lloyd.com writes:

  	  Quote: 	
		  -->    Yak-List message posted by: Brian Lloyd brian-1927(at)lloyd.com (brian-1927(at)lloyd.com) 	
 Perhaps one of the flow restrictors (that keep the gear from slamming  up) in the lines at the "B" nut, has gotten crap on it or corroded  up.

  

 Pappy

  

  

  	  Quote: 	
		  



On Sep 13, 2007, at 10:53 AM, Tim Gagnon wrote:



 	  Quote: 	
		      Like I said before, all was well UNTIL my primary bottle died. The     

 gear would come up and go down with a nice thud. New bigger    bottle,  

 slow gear and pressure drop. Are there some physics    involved here?


	


Look for crud blocking the line to the bottle and    keeping it from  

feeding air to the rest of the    system.

--

Brian Lloyd                            3191 Western Drive

brian    HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA    95682

+1.916.367.2131 (voice)                +1.270.912.0788 (fax)



I fly because it releases my mind    from the tyranny of petty things . . .

â€” Antoine de    Saint-ExupÃ©ry



PGP key ID:             12095C52A32A1B6C

PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09    1209 5C52 A32A 1B6C



	


Make AOL Your Homepage.

  [quote][b]

bwade154(at)yahoo.com
Guest

Posted: Thu Sep 13, 2007 5:12 pm Post subject: MF'ing air system! Yak-50

Hi Tim you mentioned that the actuators were rebuilt also, what if the rubber seals were put on the piston backwards? it would be a simple mistake and allow the air to bypass the first seal and go to the second seal I think at the point of almost lock up or down it would back bleed to the other line. The fix would probably require that the actuators come back out and be taken apart but I think its a possibility. Good luck



Tim Gagnon <NiftyYak50(at)fuse.net> wrote:   [quote]--> Yak-List message posted by: "Tim Gagnon" 



Let me ask this..would a smaller diameter line than original cause enough a restriction to explain the problems I am having.





Read this topic online to amazing places on Yahoo! Travel.  [quote][b]

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Thu Sep 13, 2007 5:30 pm Post subject: Re: MF'ing air system! Yak-50

 	  Quote: 	
		  

Hi Tim you mentioned that the actuators were rebuilt also, what if the rubber seals were put on the piston backwards? it would be a simple mistake and allow the air to bypass the first seal and go to the second seal I think at the point of almost lock up or down it would back bleed to the other line. The fix would probably require that the actuators come back out and be taken apart but I think its a possibility. Good luck 	




They were shipped to someone who does quite a few overhauls. That is not to say that this could not happen....if I had done them....we would more than likely be talking about a gear up accident.  Thanks for that thought though...now I really will not sleep!!!

brian-1927(at)lloyd.com
Guest

Posted: Thu Sep 13, 2007 6:08 pm Post subject: MF'ing air system! Yak-50

On Sep 13, 2007, at 5:03 PM, Tim Gagnon wrote:



 	  Quote: 	
		   



 Let me ask this..would a smaller diameter line than original cause  

 enough a restriction to explain the problems I am having.


	


Probably not. It would take a restriction that takes the line down to  

something like a pinhole to really cause a problem. OTOH, if you made  

a new flex line you might have cut a flap in the rubber interior that  

could block the line. The flap of rubber could potentially function  

as a one-way valve.



--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry



PGP key ID:          12095C52A32A1B6C

PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C

viperdoc(at)mindspring.co
Guest

Posted: Thu Sep 13, 2007 6:44 pm Post subject: MF'ing air system! Yak-50

Answer...quit possible. This being based on Bernolli's principle. A small

line introduces a venture effect. There will be a drop in pressure at the

point that the smaller line is connected to the larger line. There is an

increase in pressure at the point of constriction with resistance to flow.

At the point of dilation past the point of constriction there is a drop in

pressure with a decrease in flow. The pressure will be lower in the system

past the point of restriction. The density of air is also a factor too, but

for this agreement you can assume that number is constant.  

Doc 



--

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