Today's Message Index:
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1. 08:30 AM - YAK Pneumatic Lubricant (long post) (Rob Rowe)
2. 08:45 AM - Re: YAK Pneumatic Lubricant (long post) (Bitterlich, Mark G CIV NAVAIR, WD)
3. 12:10 PM - Re: YAK Pneumatic Lubricant (long post) (Jan Mevis)
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| Subject: | YAK Pneumatic Lubricant (long post) |
I've been researching YAK pneumatic lubricants over some years and with recent
posts on this topic (and some recent progress) I thought I'd share my thoughts
for your consideration.
1 - Nowhere in the YAK (-52) maintenance manual does it refer to using alcohol/glycerine
to lubricate the pneumatic system. The only reference you'll find for
this concoction is for drying spark plugs after they've been cleaned. Glycerine
is a viscous humectant (a substance that retains moisture) that is only soluble
in alcohol or water, hence to get it into the system alcohol has to be added
to thin it out. Once introduced at best it will absorb some moisture, but
then all of this mix needs to be blown out as soon as possible. Otherwise the
alcohol quickly evaporates leaving the viscous Glycerine residue and moisture
in the horizontal pipe runs (typically). This then tends to trap more moisture
in these runs causing the most common long term failure mode of internal pin
hole corrosion.
2 So what is the correct lubricant then? The maintenance manual states Fluid 132-25
should be used to lubricate the pneumatic system. But from what I can ascertain
Fluid 132-25 went out of production sometime in the 1980s. Given the small
quantities needed you could lubricate pretty well every -52 built with a
single 200 litre (45 US gallon) drum per annum so commercially unviable would
be my guess as to its demise. Therefore alcohol / glycerine were probably used
as a substitute as it was readily to hand for plug maintenance. Id also speculate
that with DOSAAF utilisation aircraft would be completely stripped down
every 5 years, so any problem with pipe corrosion probably wouldnt have time
to manifest.
3 To compound this issue the build-up of glycerine over time in the pipe runs
(which seems to harden - reaction with compressor acidic oil / carbon?) also reduces
the air flow and slows the gear operational times. This has led to a number
of aircraft having their air flow restrictors removed from the (rear) gear
selector connections to help bring extension/retraction times back within specification.
While this works it may lead to a more insidious problem of higher
engagement speeds with the gear up-locks at the end of the actuators travel.
This energy then gets absorbed by mounting plates inside the wing that may create
cracks in them (the subject of a YDB document in 2009 requiring borescope
inspection). At first this was thought to be just related to shock loads from
gear-up incident aircraft, but has been found to be more widespread across the
fleet here in the UK. Giving more credibility to it being a consequence of gear
engagement speed.
4 Addressing this issue in 2010 I tried to source Fluid 132-25, but while a few
East European companies claim they can produce it they never seem to have any
stock or require vast minimum order quantities to be made. Finally through the
personal contacts of a UK based Russian engineer a chemical company in the
Ukraine agreed to make a few litres in their labs, which has been used on some
YAKs here in the UK (including mine) for the last few years. With the current
difficulties in the Ukraine its unlikely to be repeatable source. The results
on my -52 have been positive, the gear cycle times noticeably decreased through
improved lubrication to the extent that the air flow restrictors could be re-installed.
Annual monitoring of the up-lock related internal cracks have shown
no further increase. Better still the UK CAA allows its use, as an originally
specified lubricant, without further approval.
5 So what is Fluid 132-25? The Russian GOST 10957-74 specification describes it
as an organo-silicon, and on closer examination its a Polyethylsiloxane (PES),
the ethyl bit gives good low temperature viscosity pour characteristics (-70C).
Essentially a silicone fluid thats a moisture displacement agent and lubricant.
But PES products are niche and difficult to source, not too surprisingly
given the above history. However having done some further research into this
there is a Dow Corning product that might be a suitable alternative. While its
a Polydimethylsiloxane (PDMS) the low temperature pour characteristics (-65C)
are very nearly as good and its also available within the lower viscosity range
of the Fluid 132-25 spec (190-290cSt). Having readily sourced some commercially
in the UK in a 1 litre quantity Ive saturated some old pneumatic seals in
this PDMS silicone fluid for some 6 months now with no adverse effects on the
seals apparent integrity. There has been a seal mass reduction during this time
of 3-4%, although this may be due to contaminant leaching from the old seals.
Im now at the stage of approaching the UK CAA for a minor modification approval
for use on UK registered YAKs.
AS SUCH I HAVE TO RAISE A WARNING THAT I TAKE NO RESPONSIBILTY WHATSOEVER FOR ANY
ADVERSE EFFECTS ON YOUR AIRCRAFT AND IF YOU CHOOSE TO USE IT THEN ITS COMPLETELY
AT YOUR OWN VOLITION AND RISK.
The product is Dow Corning Xiameter PMX-200 Silicone Fluid (200cSt) and is available
in a variety of viscosities. The 200cSt viscosity is the only one closely
meeting the Fluid 132-25 specification.
Note - PMX-200 is a brand name not a viscosity rating; hence PMX-200 (200cSt) is
the specific viscosity required of this product.
Ive posted PDFs of the Russian GOST 10957-74 (Cyrillic) and Dow Corning PMX-200
specifications for reference.
Hope this is of some use to the YAK community.
Brgds, Rob R.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=446686#446686
Attachments:
http://forums.matronics.com//files/tds_pmx200_1000cs_602.pdf
http://forums.matronics.com//files/gost_10957_74_645.pdf
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| Subject: | YAK Pneumatic Lubricant (long post) |
I'd say that about sums it up. My take away from this excellent write-up is that
a lot of people have probably been putting the wrong fluid into their systems.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Rob Rowe
Sent: Wednesday, September 02, 2015 11:27 AM
Subject: Yak-List: YAK Pneumatic Lubricant (long post)
I've been researching YAK pneumatic lubricants over some years and with recent
posts on this topic (and some recent progress) I thought I'd share my thoughts
for your consideration.
1 - Nowhere in the YAK (-52) maintenance manual does it refer to using alcohol/glycerine
to lubricate the pneumatic system. The only reference you'll find for
this concoction is for drying spark plugs after they've been cleaned. Glycerine
is a viscous humectant (a substance that retains moisture) that is only soluble
in alcohol or water, hence to get it into the system alcohol has to be added
to thin it out. Once introduced at best it will absorb some moisture, but
then all of this mix needs to be blown out as soon as possible. Otherwise the
alcohol quickly evaporates leaving the viscous Glycerine residue and moisture
in the horizontal pipe runs (typically). This then tends to trap more moisture
in these runs causing the most common long term failure mode of internal pin
hole corrosion.
2 So what is the correct lubricant then? The maintenance manual states Fluid 132-25
should be used to lubricate the pneumatic system. But from what I can ascertain
Fluid 132-25 went out of production sometime in the 1980s. Given the small
quantities needed you could lubricate pretty well every -52 built with a
single 200 litre (45 US gallon) drum per annum so commercially unviable would
be my guess as to its demise. Therefore alcohol / glycerine were probably used
as a substitute as it was readily to hand for plug maintenance. Id also speculate
that with DOSAAF utilisation aircraft would be completely stripped down
every 5 years, so any problem with pipe corrosion probably wouldnt have time
to manifest.
3 To compound this issue the build-up of glycerine over time in the pipe runs
(which seems to harden - reaction with compressor acidic oil / carbon?) also reduces
the air flow and slows the gear operational times. This has led to a number
of aircraft having their air flow restrictors removed from the (rear) gear
selector connections to help bring extension/retraction times back within specification.
While this works it may lead to a more insidious problem of higher
engagement speeds with the gear up-locks at the end of the actuators travel.
This energy then gets absorbed by mounting plates inside the wing that may create
cracks in them (the subject of a YDB document in 2009 requiring borescope
inspection). At first this was thought to be just related to shock loads from
gear-up incident aircraft, but has been found to be more widespread across the
fleet here in the UK. Giving more credibility to it being a consequence of gear
engagement speed.
4 Addressing this issue in 2010 I tried to source Fluid 132-25, but while a few
East European companies claim they can produce it they never seem to have any
stock or require vast minimum order quantities to be made. Finally through the
personal contacts of a UK based Russian engineer a chemical company in the
Ukraine agreed to make a few litres in their labs, which has been used on some
YAKs here in the UK (including mine) for the last few years. With the current
difficulties in the Ukraine its unlikely to be repeatable source. The results
on my -52 have been positive, the gear cycle times noticeably decreased through
improved lubrication to the extent that the air flow restrictors could be re-installed.
Annual monitoring of the up-lock related internal cracks have shown
no further increase. Better still the UK CAA allows its use, as an originally
specified lubricant, without further approval.
5 So what is Fluid 132-25? The Russian GOST 10957-74 specification describes it
as an organo-silicon, and on closer examination its a Polyethylsiloxane (PES),
the ethyl bit gives good low temperature viscosity pour characteristics (-70C).
Essentially a silicone fluid thats a moisture displacement agent and lubricant.
But PES products are niche and difficult to source, not too surprisingly
given the above history. However having done some further research into this
there is a Dow Corning product that might be a suitable alternative. While its
a Polydimethylsiloxane (PDMS) the low temperature pour characteristics (-65C)
are very nearly as good and its also available within the lower viscosity range
of the Fluid 132-25 spec (190-290cSt). Having readily sourced some commercially
in the UK in a 1 litre quantity Ive saturated some old pneumatic seals in
this PDMS silicone fluid for some 6 months now with no adverse effects on the
seals apparent inte!
grity. There has been a seal mass reduction during this time of 3-4%, although
this may be due to contaminant leaching from the old seals. Im now at the stage
of approaching the UK CAA for a minor modification approval for use on UK registered
YAKs.
AS SUCH I HAVE TO RAISE A WARNING THAT I TAKE NO RESPONSIBILTY WHATSOEVER FOR ANY
ADVERSE EFFECTS ON YOUR AIRCRAFT AND IF YOU CHOOSE TO USE IT THEN ITS COMPLETELY
AT YOUR OWN VOLITION AND RISK.
The product is Dow Corning Xiameter PMX-200 Silicone Fluid (200cSt) and is available
in a variety of viscosities. The 200cSt viscosity is the only one closely
meeting the Fluid 132-25 specification.
Note - PMX-200 is a brand name not a viscosity rating; hence PMX-200 (200cSt) is
the specific viscosity required of this product.
Ive posted PDFs of the Russian GOST 10957-74 (Cyrillic) and Dow Corning PMX-200
specifications for reference.
Hope this is of some use to the YAK community.
Brgds, Rob R.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=446686#446686
Attachments:
http://forums.matronics.com//files/tds_pmx200_1000cs_602.pdf
http://forums.matronics.com//files/gost_10957_74_645.pdf
Message 3
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| Subject: | Re: YAK Pneumatic Lubricant (long post) |
Thanks a lot Rob! This is impressive! I'll read these documents carefully.
I was told years ago that the Soviets stopped making this fluid in the
eighties.
The glycerine/ethanol is an "ersatz" but I doubt it that the Soviet
mechanics would have used it without any instructions from above.
Anyway, as you state it very clearly, it's every Yak drivers personal
responsibility, and I absolutely concur.
So I stick with what the Lithuanians and the Russians do, in the past and
today. Until I'm convinced that the PMX-200 is a better product.
And also I have the gear thoroughly checked each year.
BR,
Jan
On 02/09/15 17:26, "Rob Rowe" <owner-yak-list-server@matronics.com on
behalf of yak-list@robrowe.plus.com> wrote:
>
>I've been researching YAK pneumatic lubricants over some years and with
>recent posts on this topic (and some recent progress) I thought I'd share
>my thoughts for your consideration.
>
>1 - Nowhere in the YAK (-52) maintenance manual does it refer to using
>alcohol/glycerine to lubricate the pneumatic system. The only reference
>you'll find for this concoction is for drying spark plugs after they've
>been cleaned. Glycerine is a viscous humectant (a substance that retains
>moisture) that is only soluble in alcohol or water, hence to get it into
>the system alcohol has to be added to thin it out. Once introduced at
>best it will absorb some moisture, but then all of this mix needs to be
>blown out as soon as possible. Otherwise the alcohol quickly evaporates
>leaving the viscous Glycerine residue and moisture in the horizontal pipe
>runs (typically). This then tends to trap more moisture in these runs
>causing the most common long term failure mode of internal pin hole
>corrosion.
>
>2 So what is the correct lubricant then? The maintenance manual
>states Fluid 132-25 should be used to lubricate the pneumatic system. But
>from what I can ascertain Fluid 132-25 went out of production sometime in
>the 1980s. Given the small quantities needed you could lubricate
>pretty well every -52 built with a single 200 litre (45 US gallon) drum
>per annum so commercially unviable would be my guess as to its
>demise. Therefore alcohol / glycerine were probably used as a substitute
>as it was readily to hand for plug maintenance. Id also speculate
>that with DOSAAF utilisation aircraft would be completely stripped down
>every 5 years, so any problem with pipe corrosion probably wouldnt
>have time to manifest.
>
>3 To compound this issue the build-up of glycerine over time in the
>pipe runs (which seems to harden - reaction with compressor acidic oil /
>carbon?) also reduces the air flow and slows the gear operational times.
>This has led to a number of aircraft having their air flow restrictors
>removed from the (rear) gear selector connections to help bring
>extension/retraction times back within specification. While this works it
>may lead to a more insidious problem of higher engagement speeds with the
>gear up-locks at the end of the actuators travel. This energy then
>gets absorbed by mounting plates inside the wing that may create cracks
>in them (the subject of a YDB document in 2009 requiring borescope
>inspection). At first this was thought to be just related to shock loads
>from gear-up incident aircraft, but has been found to be more widespread
>across the fleet here in the UK. Giving more credibility to it being a
>consequence of gear engagement speed.
>
>4 Addressing this issue in 2010 I tried to source Fluid 132-25, but
>while a few East European companies claim they can produce it they never
>seem to have any stock or require vast minimum order quantities to be
>made. Finally through the personal contacts of a UK based Russian
>engineer a chemical company in the Ukraine agreed to make a few litres in
>their labs, which has been used on some YAKs here in the UK (including
>mine) for the last few years. With the current difficulties in the
>Ukraine its unlikely to be repeatable source. The results on my -52
>have been positive, the gear cycle times noticeably decreased through
>improved lubrication to the extent that the air flow restrictors could be
>re-installed. Annual monitoring of the up-lock related internal cracks
>have shown no further increase. Better still the UK CAA allows its use,
>as an originally specified lubricant, without further approval.
>
>5 So what is Fluid 132-25? The Russian GOST 10957-74 specification
>describes it as an organo-silicon, and on closer examination its a
>Polyethylsiloxane (PES), the ethyl bit gives good low temperature
>viscosity pour characteristics (-70C). Essentially a silicone fluid
>thats a moisture displacement agent and lubricant. But PES products
>are niche and difficult to source, not too surprisingly given the above
>history. However having done some further research into this there is a
>Dow Corning product that might be a suitable alternative. While its a
>Polydimethylsiloxane (PDMS) the low temperature pour characteristics
>(-65C) are very nearly as good and its also available within the
>lower viscosity range of the Fluid 132-25 spec (190-290cSt). Having
>readily sourced some commercially in the UK in a 1 litre quantity Ive
>saturated some old pneumatic seals in this PDMS silicone fluid for some 6
>months now with no adverse effects on the seals apparent inte!
> grity. There has been a seal mass reduction during this time of 3-4%,
>although this may be due to contaminant leaching from the old seals.
>Im now at the stage of approaching the UK CAA for a minor modification
>approval for use on UK registered YAKs.
>
>AS SUCH I HAVE TO RAISE A WARNING THAT I TAKE NO RESPONSIBILTY WHATSOEVER
>FOR ANY ADVERSE EFFECTS ON YOUR AIRCRAFT AND IF YOU CHOOSE TO USE IT THEN
>ITS COMPLETELY AT YOUR OWN VOLITION AND RISK.
>
>The product is Dow Corning Xiameter PMX-200 Silicone Fluid (200cSt) and
>is available in a variety of viscosities. The 200cSt viscosity is the
>only one closely meeting the Fluid 132-25 specification.
>
>Note - PMX-200 is a brand name not a viscosity rating; hence
>PMX-200 (200cSt) is the specific viscosity required of this product.
>
>Ive posted PDFs of the Russian GOST 10957-74 (Cyrillic) and Dow
>Corning PMX-200 specifications for reference.
>
>Hope this is of some use to the YAK community.
>
>Brgds, Rob R.
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=446686#446686
>
>
>Attachments:
>
>http://forums.matronics.com//files/tds_pmx200_1000cs_602.pdf
>http://forums.matronics.com//files/gost_10957_74_645.pdf
>
>
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