Today's Message Index:
----------------------
1. 10:08 AM - Re: Re: Super-cool oil temp (Bitterlich, Mark G CIV NAVAIR, WD)
2. 10:23 AM - Re: Super-cool oil temp (apatton2)
3. 11:09 AM - Re: Super-cool oil temp (Bitterlich, Mark G CIV NAVAIR, WD)
4. 11:11 AM - Re: Re: Super-cool oil temp (Walter Lannon)
5. 07:17 PM - Re: Super-cool oil temp (apatton2)
Message 1
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| Subject: | Re: Super-cool oil temp |
Richard, I happen to have some knowledge on this topic.
Very early YAK-50's came with what guys in this country call a "Veritherm", but
in truth is nothing but a thermostat. This device, when the engine was cool,
by-passed the oil cooler and warmed the oil up faster of course. It is not
binary... meaning just open or closed. It regulates temperature and will actually
maintain oil temp where it is supposed to be, usually even with the oil
cooler door wide open.
At some point of time, there was a Russian directive, which I am sure you can find,
that REMOVED these devices from the oil cooler. The Russian logbooks for
my 1985 YAK-50 show this as being done. The result was that my oil cooler did
not have the thermostat installed at all, and it took a very long time to warm
up the oil in cold weather, just as this person is experiencing. The thermostat
itself is set to by-pass the oil cooler, and when it starts seeing warm
oil, it then runs the oil THROUGH the oil cooler. If it fails, it usually fails
in the by-pass condition, which is... I think... why the Russians removed
it. It is failed in that position, it will cook the oil and possibly ruin the
engine. In any case, my oil cooler thermostat had been removed and so noted.
I obtained one of these thermostats/veritherms out of a Russian oil cooler for
an M-14 helicopter and put it back into my YAK-50 oil cooler (easy job really)
where it now operates perfectly. I wrote all this up about a decade ago on
the YAK list.
My guess is that he does not have a stuck thermostat, but that instead he has not
got one installed at all.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Richard Goode
Sent: Thursday, January 18, 2018 1:20 AM
Subject: [Non-DoD Source] RE: Yak-List: Re: Super-cool oil temp
--> <richard.goode@russianaeros.com>
Hello Andrew,
I'm in Sri Lanka and therefore don't have access to all my technical papers in
the UK. But I am pretty sure that all or some of the oil coolers have a thermostatic
bypass valve, and until this opens, no oil goes through the oil cooler.
I suspect yours is sticking, and therefore the oil is continuing to circulate
through the oil cooler, and that is your problem.
I will investigate this more and that you know options, but I suspect we could
obtain a new valve.
Regards
Richard
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +94 (0) 81 241 5137 (Sri Lanka)
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
I'm currently in Sri Lanka but this Mail is working,and my local phone is
+94 779 132 160.
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of apatton2
Sent: Thursday, January 18, 2018 10:07 AM
Subject: Yak-List: Re: Super-cool oil temp
--> <apatton@alumni.princeton.edu>
Re: "close the gills" - everything is closed (always is on warmup... I have several
hundred hours in 50s and 52s).
Hi Richard - thanks for the note! My last -50 (a 1982 model with series 1
engine) came up to temp very rapidly and would seem to almost always stay cool.
I was wondering if there was any thermostatic regulation function in the oil system
other than the manually actuated oil cooler door. Since I haven't seen anything
that looked like a bypass valve for the oil cooler, I assumed that wasn't
the case (I could be missing it, though). That said, I didn't think it would
actually be built into the cooler itself!
I'll look again at some of the translated documents that I have to see if any light
can be shed on this. But if that's the case and this valve is "stuck" open,
then that would explain the observed phenomena.
Best,
Andrew
--------
Andrew Patton
Yak-50
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477392#477392
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| Subject: | Re: Super-cool oil temp |
Hi Mark,
Many thanks for your note. I will correspond with former owner and see if he can
tell me anything about typical oil warmup time.
In the meantime, could you point me to any places to check for a thermostat as
you suggest? Have written to Avioservice in BG as they have been a good resource
for hard to find parts previously, but I've not yet heard back.
Many thanks!
Andrew
--------
Andrew Patton
Yak-50
San Francisco, CA
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477450#477450
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| Subject: | Re: Super-cool oil temp |
Andrew, it has been 10 years ... so my memory is not picture perfect. But I do
think you would have to remove the oil cooler to know for sure. As I recall
it screws into a hole, and we had to remove a screw in cover, and replace it with
the thermostat part. I am at work and do not have access to my manuals which
MIGHT show it. I'm afraid that is the best I can do. The person who would
know for sure would be Vladimir Yastremski. He is up the street from you
in Ramona CA. Or down the street? Whatever.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of apatton2
Sent: Friday, January 19, 2018 1:23 PM
Subject: [Non-DoD Source] Yak-List: Re: Super-cool oil temp
--> <apatton@alumni.princeton.edu>
Hi Mark,
Many thanks for your note. I will correspond with former owner and see if he can
tell me anything about typical oil warmup time.
In the meantime, could you point me to any places to check for a thermostat as
you suggest? Have written to Avioservice in BG as they have been a good resource
for hard to find parts previously, but I've not yet heard back.
Many thanks!
Andrew
--------
Andrew Patton
Yak-50
San Francisco, CA
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477450#477450
Message 4
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| Subject: | Re: Super-cool oil temp |
Mark;
The same problem was addressed in the Canadian production of the North
American Harvard (predecessor of the T6) to accommodate very cold winter
operation.
A different method was used consisting of what they called a "surge valve"
in the oil out line that opened whenever the scavenge pump pressure reached
83 psi.
and directed oil to the tank rather than the oil cooler.
Scavenge pump pressure is not regulated so temperature is a major factor in
oil out viscosity. I suspect a thermostatic device would be more efficient
but also far more subject to failure.
Walt
-----Original Message-----
From: Bitterlich, Mark G CIV NAVAIR, WD
Sent: Friday, January 19, 2018 10:01 AM
Subject: RE: Yak-List: Re: Super-cool oil temp
<mark.bitterlich@navy.mil>
Richard, I happen to have some knowledge on this topic.
Very early YAK-50's came with what guys in this country call a "Veritherm",
but in truth is nothing but a thermostat. This device, when the engine was
cool, by-passed the oil cooler and warmed the oil up faster of course. It
is not binary... meaning just open or closed. It regulates temperature and
will actually maintain oil temp where it is supposed to be, usually even
with the oil cooler door wide open.
At some point of time, there was a Russian directive, which I am sure you
can find, that REMOVED these devices from the oil cooler. The Russian
logbooks for my 1985 YAK-50 show this as being done. The result was that
my oil cooler did not have the thermostat installed at all, and it took a
very long time to warm up the oil in cold weather, just as this person is
experiencing. The thermostat itself is set to by-pass the oil cooler, and
when it starts seeing warm oil, it then runs the oil THROUGH the oil cooler.
If it fails, it usually fails in the by-pass condition, which is... I
think... why the Russians removed it. It is failed in that position, it
will cook the oil and possibly ruin the engine. In any case, my oil cooler
thermostat had been removed and so noted.
I obtained one of these thermostats/veritherms out of a Russian oil cooler
for an M-14 helicopter and put it back into my YAK-50 oil cooler (easy job
really) where it now operates perfectly. I wrote all this up about a
decade ago on the YAK list.
My guess is that he does not have a stuck thermostat, but that instead he
has not got one installed at all.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Richard Goode
Sent: Thursday, January 18, 2018 1:20 AM
Subject: [Non-DoD Source] RE: Yak-List: Re: Super-cool oil temp
--> <richard.goode@russianaeros.com>
Hello Andrew,
I'm in Sri Lanka and therefore don't have access to all my technical papers
in the UK. But I am pretty sure that all or some of the oil coolers have a
thermostatic bypass valve, and until this opens, no oil goes through the oil
cooler. I suspect yours is sticking, and therefore the oil is continuing to
circulate through the oil cooler, and that is your problem.
I will investigate this more and that you know options, but I suspect we
could obtain a new valve.
Regards
Richard
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +94 (0) 81 241 5137 (Sri Lanka)
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
I'm currently in Sri Lanka but this Mail is working,and my local phone is
+94 779 132 160.
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of apatton2
Sent: Thursday, January 18, 2018 10:07 AM
Subject: Yak-List: Re: Super-cool oil temp
--> <apatton@alumni.princeton.edu>
Re: "close the gills" - everything is closed (always is on warmup... I have
several hundred hours in 50s and 52s).
Hi Richard - thanks for the note! My last -50 (a 1982 model with series 1
engine) came up to temp very rapidly and would seem to almost always stay
cool.
I was wondering if there was any thermostatic regulation function in the oil
system other than the manually actuated oil cooler door. Since I haven't
seen anything that looked like a bypass valve for the oil cooler, I assumed
that wasn't the case (I could be missing it, though). That said, I didn't
think it would actually be built into the cooler itself!
I'll look again at some of the translated documents that I have to see if
any light can be shed on this. But if that's the case and this valve is
"stuck" open, then that would explain the observed phenomena.
Best,
Andrew
--------
Andrew Patton
Yak-50
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477392#477392
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Message 5
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| Subject: | Re: Super-cool oil temp |
Thanks much, Mark and co, for the further help. I got a picture of the thermovalve
today (at least I'm pretty sure this is it).
--------
Andrew Patton
Yak-50
San Francisco, CA
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477461#477461
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