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new air problem

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Bill1200

Joined: 19 Oct 2008
Posts: 111
Location: medford oregon

Posted: Wed Jun 02, 2010 7:28 am Post subject: new air problem

Replaced compressor 7 months ago and all has been well, until.....

Left the air valve open by mistake after a flight about 3 weeks ago. Pressure had bled down to about 2, when I got back a few days later. Thought no big deal, filled it up externally and went about my flight. Then on the next flight prep noticed the pressure down to about 3, checked the valve which was off. Started OK at 3, but noticed VERY slow build up, barely got up to 4 during the flight. Checked the snot valve yesterday and seems good (no leak). Checked pressure after several days on the ground with no loss of pressure (valve off). Took the pressure down to 2 by actuating flaps, ran at 50% sitting on the ground, took about 10minutes to get to 3.

Another thing I've noticed, when I fill it externally it pops off about 6 and bleeds down to about 5.5. Never has the compressor got up to 5.5 either the old one or the new one. Don;t understand that.

So, question is where to start looking for MOST likely leak source??????

LawnDart

Joined: 05 Jun 2006
Posts: 64

Posted: Wed Jun 02, 2010 7:39 am Post subject: Re: new air problem

Most likely the line from compressor to snot bottle.  They can develop hairline cracks and cause the slow build-up symptom (I find clacks near the fitting near snot bottle).  Another possibility is are the fittings at the compressor.

Bill1200

Joined: 19 Oct 2008
Posts: 111
Location: medford oregon

Posted: Wed Jun 02, 2010 8:00 am Post subject: Re: new air problem

Thanks, spray soapy water in those areas? Also heard about an electronic air leak detector. Any truth to that?

kingcj6(at)aol.com
Guest

Posted: Wed Jun 02, 2010 8:11 am Post subject: new air problem

Amprobe ULD 300 Ultrasonic Gas Leak Detector

 

   --

mark.bitterlich(at)navy.m
Guest

Posted: Wed Jun 02, 2010 8:15 am Post subject: new air problem

LawnDart (which is what we call F-18's in the Corps) mentioned the line

going from the compressor to the snot valve.  This line ... The one with

the "loop" in it .........fails a lot.  Which is why in some other

Russian designs (notably the Sukhoi's) they replace this with a steel

braided flex line, which is what I have done as well in my YAK-50.

Problem solved.  I think Doug Sapp might even be able to make these

things for you.  Not sure, but worth asking.  He also mentioned there

can be leaks in the Banjo Fitting at the compressor.  This is also right

on the money, and there is check valve in there that can leak as well.

What I have done is to reverse pressurize this line by removing it from

the snot valve, and then hooking it to a high pressure source and

applying 700 psi and listening for leaks.  The Banjo Fitting at the

compressor uses crush washers and if you don't put in new ones once you

have taken it apart and put it back together again, it might leak.  I've

gotten away with not using new ones a few times, but .... Luck of the

draw. 



I will offer one more thing.  I have noticed that when I have had to use

the external filling port, that if I am not careful I can put in WAY too

much air in there VERY quickly, with the result that the pop-off valve

really starts banging away.  No big deal right?  Well, not so fast.

After I have done that, the stupid thing starts to LEAK!  Usually this

happens on an aircraft that has not had the pop-off seal replaced in a

blue moon, and the abuse of having it really go nuts during a ground air

fill-up is the straw that broke the camels back.  Another good

indication of the beginning of the end is a pop-off valve that hisses

and very slowly seats, which is about what you were describing.  



There is difference somewhere in the air design between the YAK-50 and

52, and since I don't own a 52 I really would feel better asking Dennis

about this... But for example on the 50, the emergency air bottle is

filled by the compressor, and in the 52 it is only filled from the

external source.  I also am not sure about the check valve differences

between the 50 and 52.  It is POSSIBLE that on the 52 that the pop-off

valve is still in the loop even with the bottle valve closed.  Not sure

of that... It's out of the loop in the 50... But I just don't know on

the 52. 



Bottom line: 



It might also be worth your time looking at the pop-off valve for slow

leaks.  It also might cause slow pressurization with the engine running.

You can also take high pressure air and put it into the system just like

the compressor does from the snot valve fitting and check for leaks that

way too.   



Mark Bitterlich



P.s.  A good indication of whether you have a cracked line, or leaking

banjo fitting from the compressor to the snot valve is to follow this

simple test.  Start engine, let the pressure come up just a tad, then

shut everything down and closed all valves.  Wait about 15 minutes or so

and then open the snot valve.  Do you get a good rush of air like you

usually do?  If you do, then more than likely you have no leaks between

the compressor and the snot valve.   If you open the snot valve and get

no air rushing out, or much less than you remember from the past, then

you probably do have a leak in that area.  

 



--

Bill1200

Joined: 19 Oct 2008
Posts: 111
Location: medford oregon

Posted: Wed Jun 02, 2010 8:34 am Post subject: Re: new air problem

Thanks so much. That may very well be it. I've noticed after last couple of flights when I open the snot valve I don't hear it from the cockpit which I usually can.

ph451(at)yahoo.com
Guest

Posted: Wed Jun 02, 2010 2:45 pm Post subject: new air problem

Lawn darts are F-16s



--- On Wed, 6/2/10, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil> wrote:

 [quote]

From: Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil>

Subject: RE: new air problem

To: yak-list(at)matronics.com

Date: Wednesday, June 2, 2010, 5:14 PM



 --> Yak-List message posted by: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



LawnDart (which is what we call F-18's in the Corps) mentioned the line

going from the compressor to the snot valve.  This line ... The one with

the "loop" in it .........fails a lot.  Which is why in some other

Russian designs (notably the Sukhoi's) they replace this with a steel

braided flex line, which is what I have done as well in my YAK-50.

Problem solved.  I think Doug Sapp might even be able to make these

things for you.  Not sure, but worth asking.  He also mentioned there

can be leaks in the Banjo Fitting at the compressor.  This is also right

on the money, and there is check valve in there that can leak as  well.

What I have done is to reverse pressurize this line by removing it from

the snot valve, and then hooking it to a high pressure source and

applying 700 psi and listening for leaks.  The Banjo Fitting at the

compressor uses crush washers and if you don't put in new ones once you

have taken it apart and put it back together again, it might leak.  I've

gotten away with not using new ones a few times, but .... Luck of the

draw. 



I will offer one more thing.  I have noticed that when I have had to use

the external filling port, that if I am not careful I can put in WAY too

much air in there VERY quickly, with the result that the pop-off valve

really starts banging away.  No big deal right?  Well, not so fast.

After I have done that, the stupid thing starts to LEAK!  Usually this

happens on an aircraft that has not had the pop-off seal replaced in a

blue moon, and the abuse of  having it really go nuts during a ground air

fill-up is the straw that broke the camels back.  Another good

indication of the beginning of the end is a pop-off valve that hisses

and very slowly seats, which is about what you were describing.  



There is difference somewhere in the air design between the YAK-50 and

52, and since I don't own a 52 I really would feel better asking Dennis

about this... But for example on the 50, the emergency air bottle is

filled by the compressor, and in the 52 it is only filled from the

external source.  I also am not sure about the check valve differences

between the 50 and 52.  It is POSSIBLE that on the 52 that the pop-off

valve is still in the loop even with the bottle valve closed.  Not sure

of that... It's out of the loop in the 50... But I just don't know on

the 52. 



Bottom line: 



It might also be worth your time looking at the pop-off  valve for slow

leaks.  It also might cause slow pressurization with the engine running.

You can also take high pressure air and put it into the system just like

the compressor does from the snot valve fitting and check for leaks that

way too.   



Mark Bitterlich



P.s.  A good indication of whether you have a cracked line, or leaking

banjo fitting from the compressor to the snot valve is to follow this

simple test.  Start engine, let the pressure come up just a tad, then

shut everything down and closed all valves.  Wait about 15 minutes or so

and then open the snot valve.  Do you get a good rush of air like you

usually do?  If you do, then more than likely you have no leaks between

the compressor and the snot valve.   If you open the snot valve and get

no air rushing out, or much less than you remember from the past, then

you probably do have a  leak in that area.  

--

radiopicture

Joined: 23 Jun 2008
Posts: 263

Posted: Wed Jun 02, 2010 2:53 pm Post subject: new air problem

Lawn darts were sold under the trade name "Jarts", and featured a weighted, sharpened business end until some newly disfigured whiner sued. Don't see what airplanes have to do with this.

On Jun 2, 2010, at 6:43 PM, Paul Hamlin wrote:

[quote]Lawn darts are F-16s



--- On Wed, 6/2/10, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

 [quote]

From: Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>

Subject: RE: new air problem

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

Date: Wednesday, June 2, 2010, 5:14 PM



 --> Yak-List message posted by: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



LawnDart (which is what we call F-18's in the Corps) mentioned the line

going from the compressor to the snot valve.  This line .. The one with

the "loop" in it .........fails a lot.  Which is why in some other

Russian designs (notably the Sukhoi's) they replace this with a steel

braided flex line, which is what I have done as well in my YAK-50.

Problem solved.  I think Doug Sapp might even be able to make these

things for you.  Not sure, but worth asking.  He also mentioned there

can be leaks in the Banjo Fitting at the compressor.  This is also right

on the money, and there is check valve in there that can leak as well.

What I have done is to reverse pressurize this line by removing it from

the snot valve, and then hooking it to a high pressure source and

applying 700 psi and listening for leaks.  The Banjo Fitting at the

compressor uses crush washers and if you don't put in new ones once you

have taken it apart and put it back together again, it might leak.  I've

gotten away with not using new ones a few times, but ... Luck of the

draw. 



I will offer one more thing.  I have noticed that when I have had to use

the external filling port, that if I am not careful I can put in WAY too

much air in there VERY quickly, with the result that the pop-off valve

really starts banging away.  No big deal right?  Well, not so fast.

After I have done that, the stupid thing starts to LEAK!  Usually this

happens on an aircraft that has not had the pop-off seal replaced in a

blue moon, and the abuse of having it really go nuts during a ground air

fill-up is the straw that broke the camels back.  Another good

indication of the beginning of the end is a pop-off valve that hisses

and very slowly seats, which is about what you were describing.  



There is difference somewhere in the air design between the YAK-50 and

52, and since I don't own a 52 I really would feel better asking Dennis

about this... But for example on the 50, the emergency air bottle is

filled by the compressor, and in the 52 it is only filled from the

external source.  I also am not sure about the check valve differences

between the 50 and 52.  It is POSSIBLE that on the 52 that the pop-off

valve is still in the loop even with the bottle valve closed.  Not sure

of that... It's out of the loop in the 50... But I just don't know on

the 52. 



Bottom line: 



It might also be worth your time looking at the pop-off valve for slow

leaks.  It also might cause slow pressurization with the engine running.

You can also take high pressure air and put it into the system just like

the compressor does from the snot valve fitting and check for leaks that

way too.   



Mark Bitterlich



P.s.  A good indication of whether you have a cracked line, or leaking

banjo fitting from the compressor to the snot valve is to follow this

simple test.  Start engine, let the pressure come up just a tad, then

shut everything down and closed all valves.  Wait about 15 minutes or so

and then open the snot valve.  Do you get a good rush of air like you

usually do?  If you do, then more than likely you have no leaks between

the compressor and the snot valve.   If you open the snot valve and get

no air rushing out, or much less than you remember from the past, then

you probably do have a leak in that area.  

--

viperdoc(at)mindspring.co
Guest

Posted: Wed Jun 02, 2010 7:32 pm Post subject: new air problem

That would be true. Now do you know what AF Base was associated with that terminology? Hint it was the first operation base for the F-16 A as they came into the inventory.  

Doc  

     

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Paul Hamlin

 Sent: Wednesday, June 02, 2010 5:43 PM

 To: yak-list(at)matronics.com

 Subject: RE: new air problem  

  

           

Lawn darts are F-16s

   

   --- On Wed, 6/2/10, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil>   wrote:   



   From: Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E   <mark.bitterlich(at)navy.mil>

   Subject: RE: new air problem

   To: yak-list(at)matronics.com

   Date: Wednesday, June 2, 2010, 5:14 PM      

--> Yak-List message posted by: "Bitterlich, Mark   G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil>

   

   LawnDart (which is what we call F-18's in the Corps) mentioned the line

   going from the compressor to the snot valve.  This line ... The one with

   the "loop" in it .........fails a lot.  Which is why in some   other

   Russian designs (notably the Sukhoi's) they replace this with a steel

   braided flex line, which is what I have done as well in my YAK-50.

   Problem solved.  I think Doug Sapp might even be able to make these

   things for you.  Not sure, but worth asking.  He also mentioned   there

   can be leaks in the Banjo Fitting at the compressor.  This is also right

   on the money, and there is check valve in there that can leak as well.

   What I have done is to reverse pressurize this line by removing it from

   the snot valve, and then hooking it to a high pressure source and

   applying 700 psi and listening for leaks.  The Banjo Fitting at the

   compressor uses crush washers and if you don't put in new ones once you

   have taken it apart and put it back together again, it might leak.  I've

   gotten away with not using new ones a few times, but .... Luck of the

   draw. 

   

   I will offer one more thing.  I have noticed that when I have had to use

   the external filling port, that if I am not careful I can put in WAY too

   much air in there VERY quickly, with the result that the pop-off valve

   really starts banging away.  No big deal right?  Well, not so fast.

   After I have done that, the stupid thing starts to LEAK!  Usually this

   happens on an aircraft that has not had the pop-off seal replaced in a

   blue moon, and the abuse of having it really go nuts during a ground air

   fill-up is the straw that broke the camels back.  Another good

   indication of the beginning of the end is a pop-off valve that hisses

   and very slowly seats, which is about what you were describing.  

   

   There is difference somewhere in the air design between the YAK-50 and

   52, and since I don't own a 52 I really would feel better asking Dennis

   about this... But for example on the 50, the emergency air bottle is

   filled by the compressor, and in the 52 it is only filled from the

   external source.  I also am not sure about the check valve differences

   between the 50 and 52.  It is POSSIBLE that on the 52 that the pop-off

   valve is still in the loop even with the bottle valve closed.  Not sure

   of that... It's out of the loop in the 50... But I just don't know on

   the 52. 

   

   Bottom line: 

   

   It might also be worth your time looking at the pop-off valve for slow

   leaks.  It also might cause slow pressurization with the engine running.

   You can also take high pressure air and put it into the system just like

   the compressor does from the snot valve fitting and check for leaks that

   way too.   

   

   Mark Bitterlich

   

   P.s.  A good indication of whether you have a cracked line, or leaking

   banjo fitting from the compressor to the snot valve is to follow this

   simple test.  Start engine, let the pressure come up just a tad, then

   shut everything down and closed all valves.  Wait about 15 minutes or so

   and then open the snot valve.  Do you get a good rush of air like you

   usually do?  If you do, then more than likely you have no leaks between

   the compressor and the snot valve.   If you open the snot   valve and get

   no air rushing out, or much less than you remember from the past, then

   you probably do have a leak in that area.  

   

   

   --

William Halverson

Joined: 27 Feb 2010
Posts: 88

Posted: Wed Jun 02, 2010 10:22 pm Post subject: new air problem

Luke?

+--

viperdoc(at)mindspring.co
Guest

Posted: Thu Jun 03, 2010 5:07 am Post subject: new air problem

Key word first operational base. Not training base. Hill AFB was the first

operational base. The Viper got the nick name "Lawn Dart" because of many of

the GE 100 engines fuel flow controllers were failing causing obviously loss

of power. That resulted in a number of A models being parked in the Utah

desert. Hence the name "Lawn Dart". The joke used to be if you want an F-16

buy land in Utah. One will drop in before long.

Doc



--

mark.bitterlich(at)navy.m
Guest

Posted: Thu Jun 03, 2010 9:02 am Post subject: new air problem

I am sure you're both right.  In truth, the USMC has always had to steal

all the good stuff from the Air Force.  



I guess nothing's changed... 



Mark

 



--

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