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jan.mevis(at)informavia.b
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 Posted: Sun Jan 11, 2009 9:51 pm Post subject: strange behaviour pressure gauge |
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We’ve had some unusually cold weather here in Western Europe (-20 degrees celsius in Namur, Belgium). I don’t know if there’s any correlation, but the needle of the main pressure gauge in my Yak 50 is now in the other half of the instrument (at the side of the emergency pressure indicator) at about two o’clock. Emergency pressure is still at the normal 60 kg/cm. The aircraft was last flown at the end of december 2008, just before the extremely cold weather. And at that time everything was normal.
I have depleted the main pressure system completely. The needle moved back to the left a little, and stopped at about 11 o’clock. The amount of motion to the left of the needle when depleting could correspond with a presence of about 30 kg/cm in the main circuit (quite normal in my Yak 50 after some time).
I charged again until I heard the relief valve. I know that this corresponds with 50 kg/cm, but the needle of the main pressure was again at two o’clock.
Of course the instrument may be broken, but even stranger: in the same hangar we have a Yak 52 WITH EXACTLY THE SAME PHENOMENON. In this 52, the needle of the main pressure is also at about two o’clock. Although the pressure on this aircraft must have been relatively normal, because we could start it without difficulties.
Has anyone seen this before ?
Jan Mevis
Yak 50
RA2005K
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dsavarese0812(at)bellsout
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| Posted: Mon Jan 12, 2009 4:16 am Post subject: strange behaviour pressure gauge |
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Jan,
Since you have a 52 exhibiting the same symptom, did you check both the front and rear instruments in the 52 and if so are they reading the same?
Dennis
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jan.mevis(at)informavia.b
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| Posted: Mon Jan 12, 2009 4:46 am Post subject: strange behaviour pressure gauge |
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Yes, we checked, and the rear instrument was more or less “normal” (but low).
I start to think that the problem must be due to enclosed humidity.
Jan
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: maandag 12 januari 2009 13:15
To: yak-list(at)matronics.com
Subject: Re: strange behaviour pressure gauge
Jan,
Since you have a 52 exhibiting the same symptom, did you check both the front and rear instruments in the 52 and if so are they reading the same?
Dennis
| Quote: |
----- Original Message -----
From: Jan Mevis (jan.mevis(at)informavia.be)
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Sunday, January 11, 2009 11:50 PM
Subject: strange behaviour pressure gauge
We’ve had some unusually cold weather here in Western Europe (-20 degrees celsius in Namur, Belgium). I don’t know if there’s any correlation, but the needle of the main pressure gauge in my Yak 50 is now in the other half of the instrument (at the side of the emergency pressure indicator) at about two o’clock. Emergency pressure is still at the normal 60 kg/cm. The aircraft was last flown at the end of december 2008, just before the extremely cold weather. And at that time everything was normal.
I have depleted the main pressure system completely. The needle moved back to the left a little, and stopped at about 11 o’clock. The amount of motion to the left of the needle when depleting could correspond with a presence of about 30 kg/cm in the main circuit (quite normal in my Yak 50 after some time).
I charged again until I heard the relief valve. I know that this corresponds with 50 kg/cm, but the needle of the main pressure was again at two o’clock.
Of course the instrument may be broken, but even stranger: in the same hangar we have a Yak 52 WITH EXACTLY THE SAME PHENOMENON. In this 52, the needle of the main pressure is also at about two o’clock. Although the pressure on this aircraft must have been relatively normal, because we could start it without difficulties.
Has anyone seen this before ?
Jan Mevis
Yak 50
RA2005K | Quote: | | href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-Listhref="http://forums.matronics.com">http://forums.matronics.comhref="http://www.matronics.com/contribution">http://www.matronics.com/c |
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dsavarese0812(at)bellsout
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| Posted: Mon Jan 12, 2009 4:53 am Post subject: strange behaviour pressure gauge |
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Ahhhh. Based on that, I think you have 2 instruments (one in the 50 and one in the 52) that are not operating correctly in the very cold weather. You may try warming the instruments slowly with a hair dryer and see if the pressure reading drops back to "normal".
Dennis
[quote] ---
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jan.mevis(at)informavia.b
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| Posted: Mon Jan 12, 2009 5:17 am Post subject: strange behaviour pressure gauge |
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Thanks, will try that !
Jan
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: maandag 12 januari 2009 13:52
To: yak-list(at)matronics.com
Subject: Re: strange behaviour pressure gauge
Ahhhh. Based on that, I think you have 2 instruments (one in the 50 and one in the 52) that are not operating correctly in the very cold weather. You may try warming the instruments slowly with a hair dryer and see if the pressure reading drops back to "normal".
Dennis
| Quote: |
----- Original Message -----
From: Jan Mevis (jan.mevis(at)informavia.be)
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Monday, January 12, 2009 6:44 AM
Subject: RE: Yak-List: strange behaviour pressure gauge
Yes, we checked, and the rear instrument was more or less “normal” (but low).
I start to think that the problem must be due to enclosed humidity.
Jan
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese
Sent: maandag 12 januari 2009 13:15
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: strange behaviour pressure gauge
Jan,
Since you have a 52 exhibiting the same symptom, did you check both the front and rear instruments in the 52 and if so are they reading the same?
Dennis
| Quote: |
----- Original Message -----
From: Jan Mevis (jan.mevis(at)informavia.be)
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Sunday, January 11, 2009 11:50 PM
Subject: strange behaviour pressure gauge
We’ve had some unusually cold weather here in Western Europe (-20 degrees celsius in Namur, Belgium). I don’t know if there’s any correlation, but the needle of the main pressure gauge in my Yak 50 is now in the other half of the instrument (at the side of the emergency pressure indicator) at about two o’clock. Emergency pressure is still at the normal 60 kg/cm. The aircraft was last flown at the end of december 2008, just before the extremely cold weather. And at that time everything was normal.
I have depleted the main pressure system completely. The needle moved back to the left a little, and stopped at about 11 o’clock. The amount of motion to the left of the needle when depleting could correspond with a presence of about 30 kg/cm in the main circuit (quite normal in my Yak 50 after some time).
I charged again until I heard the relief valve. I know that this corresponds with 50 kg/cm, but the needle of the main pressure was again at two o’clock.
Of course the instrument may be broken, but even stranger: in the same hangar we have a Yak 52 WITH EXACTLY THE SAME PHENOMENON. In this 52, the needle of the main pressure is also at about two o’clock. Although the pressure on this aircraft must have been relatively normal, because we could start it without difficulties.
Has anyone seen this before ?
Jan Mevis
Yak 50
RA2005K | Quote: | | href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-Listhref="http://forums.matronics.com">http://forums.matronics.comhref="http://www.matronics.com/contribution">http://www.matronics.com/c |
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nc69666(at)aol.com
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| Posted: Mon Jan 12, 2009 8:04 am Post subject: strange behaviour pressure gauge |
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Remove the pressure gauge and check the orface where the air pressure enters the instrument, I had a similular occurance on my CJ, I found the opening with a small amount of corrision in the opening, It is made of brass.. What I did was to take a very fine probe and worked the blockage out ot the opening, there was some pressure trapped in the instrument so when I loosened the obstruction, the pressure in the gauge blew the debris out of the opening.. It has worked fine ever since..
Gary CJ N22YK
--
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jan.mevis(at)informavia.b
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| Posted: Mon Jan 12, 2009 9:10 am Post subject: strange behaviour pressure gauge |
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Thank you all for the ideas.
So, the different possibilities:
<![if !supportLists]>- <![endif]>Frozen water in the lines; if that is the case, the problem should disappear after warming up the aircraft (we’ll put a small bathroom heater with thermostate inside the cockpits to check, since it is still way too cold here);
<![if !supportLists]>- <![endif]>An obstruction at the entrance of the gauges; if the first option does not work, we’ll take the gauges out to verify the orifice at the entrance;
<![if !supportLists]>- <![endif]>Gauges severely damaged in one way or another (apparently they have seen cracked up gauges in Russia in times of extreme cold) , in which case they have to be replaced.
As soon as I have a conclusive result, I’ll inform the list. It will be interesting to see if both the Yak 50 and the Yak 52 have the same diagnosis.
Jan Mevis
YK50 RA2005K
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of nc69666(at)aol.com
Sent: maandag 12 januari 2009 17:03
To: yak-list(at)matronics.com
Subject: Re: strange behaviour pressure gauge
Remove the pressure gauge and check the orface where the air pressure enters the instrument, I had a similular occurance on my CJ, I found the opening with a small amount of corrision in the opening, It is made of brass.. What I did was to take a very fine probe and worked the blockage out ot the opening, there was some pressure trapped in the instrument so when I loosened the obstruction, the pressure in the gauge blew the debris out of the opening.. It has worked fine ever since..
Gary CJ N22YK
--
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http://www.matronics.com/Navigator?Yak-List |
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petervs(at)knology.net
Guest
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| Posted: Mon Jan 12, 2009 9:49 am Post subject: strange behaviour pressure gauge |
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Jan,
My guess is that water has collected in the gauge, frozen, bent the diaphragm.
Pete
__|__
__|__ ----=(*)=---- __|__
----=(*)=---- __|__ ----=(*)=----
----=(*)=----
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Jan Mevis
Sent: Monday, January 12, 2009 11:09 AM
To: yak-list(at)matronics.com
Subject: RE: strange behaviour pressure gauge
Thank you all for the ideas.
So, the different possibilities:
<![if !supportLists]>- <![endif]>Frozen water in the lines; if that is the case, the problem should disappear after warming up the aircraft (we’ll put a small bathroom heater with thermostate inside the cockpits to check, since it is still way too cold here);
<![if !supportLists]>- <![endif]>An obstruction at the entrance of the gauges; if the first option does not work, we’ll take the gauges out to verify the orifice at the entrance;
<![if !supportLists]>- <![endif]>Gauges severely damaged in one way or another (apparently they have seen cracked up gauges in Russia in times of extreme cold) , in which case they have to be replaced.
As soon as I have a conclusive result, I’ll inform the list. It will be interesting to see if both the Yak 50 and the Yak 52 have the same diagnosis.
Jan Mevis
YK50 RA2005K
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of nc69666(at)aol.com
Sent: maandag 12 januari 2009 17:03
To: yak-list(at)matronics.com
Subject: Re: strange behaviour pressure gauge
Remove the pressure gauge and check the orface where the air pressure enters the instrument, I had a similular occurance on my CJ, I found the opening with a small amount of corrision in the opening, It is made of brass.. What I did was to take a very fine probe and worked the blockage out ot the opening, there was some pressure trapped in the instrument so when I loosened the obstruction, the pressure in the gauge blew the debris out of the opening.. It has worked fine ever since..
Gary CJ N22YK
--
| | - 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:
http://www.matronics.com/Navigator?Yak-List |
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jan.mevis(at)informavia.b
Guest
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| Posted: Mon Jan 12, 2009 12:17 pm Post subject: strange behaviour pressure gauge |
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In that case, I’ll have to replace it. I’ll verify asap.
Thanks!
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Peter K. Van Staagen
Sent: maandag 12 januari 2009 18:44
To: yak-list(at)matronics.com
Subject: RE: strange behaviour pressure gauge
Jan,
My guess is that water has collected in the gauge, frozen, bent the diaphragm.
Pete
__|__
__|__ ----=(*)=---- __|__
----=(*)=---- __|__ ----=(*)=----
----=(*)=----
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Jan Mevis
Sent: Monday, January 12, 2009 11:09 AM
To: yak-list(at)matronics.com
Subject: RE: strange behaviour pressure gauge
Thank you all for the ideas.
So, the different possibilities:
<![if !supportLists]>- <![endif]>Frozen water in the lines; if that is the case, the problem should disappear after warming up the aircraft (we’ll put a small bathroom heater with thermostate inside the cockpits to check, since it is still way too cold here);
<![if !supportLists]>- <![endif]>An obstruction at the entrance of the gauges; if the first option does not work, we’ll take the gauges out to verify the orifice at the entrance;
<![if !supportLists]>- <![endif]>Gauges severely damaged in one way or another (apparently they have seen cracked up gauges in Russia in times of extreme cold) , in which case they have to be replaced.
As soon as I have a conclusive result, I’ll inform the list. It will be interesting to see if both the Yak 50 and the Yak 52 have the same diagnosis.
Jan Mevis
YK50 RA2005K
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of nc69666(at)aol.com
Sent: maandag 12 januari 2009 17:03
To: yak-list(at)matronics.com
Subject: Re: strange behaviour pressure gauge
Remove the pressure gauge and check the orface where the air pressure enters the instrument, I had a similular occurance on my CJ, I found the opening with a small amount of corrision in the opening, It is made of brass.. What I did was to take a very fine probe and worked the blockage out ot the opening, there was some pressure trapped in the instrument so when I loosened the obstruction, the pressure in the gauge blew the debris out of the opening.. It has worked fine ever since..
Gary CJ N22YK
--
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jan.mevis(at)informavia.b
Guest
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| Posted: Sun Jan 18, 2009 1:10 am Post subject: strange behaviour pressure gauge |
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The ambient temperature of the hangar with the Yak 50 and the Yak 52 is at 2 degrees Celsius now for a couple of days. We also heated the cockpit with a small heat gun. After depleting the pressure lines, the main pressure indicator still kept indicating 110 kg / cm² on the 52 and 90 kg/cm² on the 50. When taking out the pressure gauges (relatively easy: only unscrew one bolt right above in the panel, the one that does not have a “cross”; this bolt opens up a large ring at the inside of the panel; this ring clamps the instrument; when opened up, you can push the instrument out of the panel – SLOWLY – and deconnect the pressure lines), so when taking out the gauges and deconnecting the lines, quite some water came out of the lines. But without pressure, the main gauge still was at 60 kg/cm². This means that the main pressure of the 52 was 50 kg/cm² and only 30 kg/cm² on the 50. Normal situation.
So we opened up the instrument. A very tiny tube goes from the orifice to a kind of half-circular box. This half circle stretches by the air pressure, and thus operates a tiny needle indicator system. It looks quite fragile, just as in the inside of a swiss watch. There are two half circular boxes, one for the main and one for the emergency pressure. But only the emergency can be “set” by two of the four screws that hold the instrument housing. Two of the four bolts are longer. For the main indicator, the only way – I suppose - to set it to zero again, is by gently pushing on the half circular box until the needle is at zero again.
We already mounted the pressure gauge back into the Yak 52, and did about 30 kg / cm² pressure in the aircraft. Now we’ll wait for a few days to see if it remains constant.
This is probably not the correct procedure to reset the gauge. Probably the instrument needs to be overhauled.
All the best,
Jan Mevis
YK50 RA2005K
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Jan Mevis
Sent: maandag 12 januari 2009 18:09
To: yak-list(at)matronics.com
Subject: RE: strange behaviour pressure gauge
Thank you all for the ideas.
So, the different possibilities:
<![if !supportLists]>- <![endif]>Frozen water in the lines; if that is the case, the problem should disappear after warming up the aircraft (we’ll put a small bathroom heater with thermostate inside the cockpits to check, since it is still way too cold here);
<![if !supportLists]>- <![endif]>An obstruction at the entrance of the gauges; if the first option does not work, we’ll take the gauges out to verify the orifice at the entrance;
<![if !supportLists]>- <![endif]>Gauges severely damaged in one way or another (apparently they have seen cracked up gauges in Russia in times of extreme cold) , in which case they have to be replaced.
As soon as I have a conclusive result, I’ll inform the list. It will be interesting to see if both the Yak 50 and the Yak 52 have the same diagnosis.
Jan Mevis
YK50 RA2005K
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of nc69666(at)aol.com
Sent: maandag 12 januari 2009 17:03
To: yak-list(at)matronics.com
Subject: Re: strange behaviour pressure gauge
Remove the pressure gauge and check the orface where the air pressure enters the instrument, I had a similular occurance on my CJ, I found the opening with a small amount of corrision in the opening, It is made of brass.. What I did was to take a very fine probe and worked the blockage out ot the opening, there was some pressure trapped in the instrument so when I loosened the obstruction, the pressure in the gauge blew the debris out of the opening.. It has worked fine ever since..
Gary CJ N22YK
--
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