Today's Message Index:
----------------------
1. 03:54 AM - Re: Low Emergency Air Pressure (Rob Rowe)
2. 07:08 AM - Re: Low Emergency Air Pressure (Yak Pilot)
3. 07:52 AM - Re: can't log in (Brian Lloyd)
4. 08:00 AM - Re: Low Emergency Air Pressure (Brian Lloyd)
5. 08:23 AM - Re: Re: Low Emergency Air Pressure (A. Dennis Savarese)
6. 08:43 AM - Re: Low Emergency Air Pressure (Walter Lannon)
7. 09:38 AM - Re: Low Emergency Air Pressure (Yak Pilot)
8. 09:39 AM - Re: Low Emergency Air Pressure (Yak Pilot)
9. 09:52 AM - Re: Low Emergency Air Pressure (Brian Lloyd)
10. 10:06 AM - Re: Low Emergency Air Pressure (Brian Lloyd)
11. 12:18 PM - Re: Low Emergency Air Pressure (Rob Rowe)
12. 12:32 PM - Re: Low Emergency Air Pressure (philg)
13. 12:38 PM - Re: Low Emergency Air Pressure (Yak Pilot)
14. 12:53 PM - Re: Re: Low Emergency Air Pressure (Brian Lloyd)
15. 12:55 PM - Re: Low Emergency Air Pressure (Brian Lloyd)
16. 02:31 PM - Dave Enrico?? (doug sapp)
17. 03:26 PM - Re: Low Emergency Air Pressure (Vic)
18. 05:10 PM - Re: Low Emergency Air Pressure (cjpilot710@aol.com)
19. 05:16 PM - Re: Low Emergency Air Pressure (Bill1200)
20. 05:29 PM - Re: Low Emergency Air Pressure (cjpilot710@aol.com)
21. 06:58 PM - Re: Low Emergency Air Pressure (Rob Rowe)
22. 08:38 PM - Re: Re: Low Emergency Air Pressure (Brian Lloyd)
Message 1
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| Subject: | Re: Low Emergency Air Pressure |
Dennis / Bill,
Believe the protection valve Bill enquired about is the one located under the starboard
side of the front cockpit seat (YAK-52).
Its vents the emergency air line (between the tap(s) and gear shuttle valves /
uplocks) to atmosphere below 5 kgf/cm2 line pressure, to stop MINOR leaks from
the taps or shuttle valve 'peas' interfering with normal gear operation.
For that very reason if you need to operate the emergency air system for real then
open the tap quickly and fully to make sure the protection valve snaps shut
(>5 kgf/cm2), otherwise you'll just waste the precious 3 litres reserve air
ventilating the P1's derriere! Keeping in mind, having lowered the gear, you may
well need what emergency air is left to also operate the brakes post landing.
Similarly the overnight air tap leak test suggested will probably be inconclusive
for a YAK-52 because the air will most likely have been dumped externally by
the protection valve as
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=351640#351640
Message 2
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| Subject: | Re: Low Emergency Air Pressure |
No, it does not.- The YAK-50 has four check valves.--Two for air inpu
t:- One from the compressor, one from the external air.- These come tog
ether at the pressure relief valve and prevent reverse flow.- =0A-=0AOu
t of the pressure relief valve you go to a "T" connector which feeds an air
strainer.- The output of the air strainer, goes to another "T" connector
where there are two more check valves.- Top one goes to emergency air bo
ttle, bottom one goes to main air bottle.- Both go DIRECTLY to the bottle
s.- The air shut off valve in the cockpit does not control air INPUT in a
ny way to either bottle.- It only controls air output. =0A-=0AMark Bitt
erlich=0A-=0A=0AFrom: Walter Lannon <wlannon@persona.ca>=0ATo: yak-list@m
atronics.com=0ASent: Wednesday, September 7, 2011 12:30 AM=0ASubject: Re: Y
ak-List: Low Emergency Air Pressure=0A=0A=0AOn the CJ if you wish to charge
the emergency tank only, for example with nitrogen rather than air simply
leave the main air valve closed.=0A-=0AProbably applies to the Yak 50 as
well=0A-=0AWalt=0A----- Original Message ----- =0A>From: Brian Lloyd =0A>
>Subject: Re: Yak-List: Low Emergency Air Pressure=0A>=0A>=0A>=0A>=0A>On Tu
e, Sep 6, 2011 at 9:25 AM, Yak Pilot <yakplt@yahoo.com> wrote:=0A>=0A>On a
YAK-52, the emergency bottle is not filled by the compressor.- Only by th
e external fill port.- =0A>>-=0A>>On the YAK-50, the compressor charges
both main and emergency.- =0A>>-=0A>>Mark Bitterlich=0A>=0A>=0A>Sorry
Mark. I was thinking CJ6A. Emergency side is filled from the compressor.=0A
>=0A>-- =0A>Brian Lloyd, WB6RQN/J79BPL=0A>3191 Western Dr.=0A>Cameron Park,
CA 95682=0A>brian@lloyd.com=0A>+1.767.617.1365 (Dominica)=0A>+1.916.877.50
67 (USA)=0A>=0A>=0A>href="http://www.matronics.com/Navigator?Yak-List">ht
tp://www.matronics.com/Navigator?Yak-Listhref="http://forums.matronics
.com">http://forums.matronics.comhref="http://www.matronics.com/contri
========================
========================
=======================
Message 3
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| Subject: | Re: can't log in |
On Tue, Sep 6, 2011 at 11:16 PM, Nigel Willson <nigel@yakdisplay.com> wrote:
>
> Matt,
>
> Whilst on the subject of "problems", something that's been bugging me for a
> while.
> On my Android phone I don't see the body of SOME of the yak list messages.
> I've nailed it down to the ones that are HTML formatted, and was wondering
> if those were the ones that people are using the web site to post to.
> It seems particular to the android (outlook sees them ok). However, other
> HTML formatted messages from other people can be read ok on the android.
> Wondered if the yak list server was doing something strange with the HTML
> (maybe has an HTML error in it) that outlook ignores and the android
> rejects
> - refusing to display the content?
>
> Any ideas?
>
Some mail user-agents (MUAs - email programs, e.g. Outlook) send a message
in two parts, plain-text and HTML. It may be that the ones you can read OK
are the ones where the plain-text part is rendered. But that is just a
supposition.
How the HTML is generated varies from one MUA to another. It could be that
your MUA has trouble. Try a webmail client. They tend to be much better
about rendering HTML since they are running in a full browser.
Good luck!
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
Message 4
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| Subject: | Re: Low Emergency Air Pressure |
On Wed, Sep 7, 2011 at 7:05 AM, Yak Pilot <yakplt@yahoo.com> wrote:
> No, it does not. The YAK-50 has four check valves. Two for air input:
> One from the compressor, one from the external air. These come together at
> the pressure relief valve and prevent reverse flow.
>
> Out of the pressure relief valve you go to a "T" connector which feeds an
> air strainer. The output of the air strainer, goes to another "T" connector
> where there are two more check valves. Top one goes to emergency air
> bottle, bottom one goes to main air bottle. Both go DIRECTLY to the
> bottles. The air shut off valve in the cockpit does not control air INPUT
> in any way to either bottle. It only controls air output.
>
> Mark Bitterlich
>
Has anyone else noticed that there are a lot more check valves in our
airplanes than are needed to ensure system integrity after a partial
failure? While helping Dennis Nickson troubleshoot an intermittent problem
with the pneumatic system in his CJ it was pretty obvious that I could
replace several of the check valves with straight pipe and it would have no
effect on either the normal operation or how the system would fail if it was
breached at various places. And I suspect that pieces of straight pipe are
less likely to fail and cause problems than the various unnecessary check
valves.
I am thinking that, right after removing and throwing away the arcane and
unnecessary complexity of the electrical system, we could probably to do the
same for much of the pneumatic system as well. :-)
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
Message 5
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| Subject: | Re: Low Emergency Air Pressure |
All excellent points Robb. Regarding the "fart" valve you mention and
refer to as the protection valve, if there is a leak from either one of
the emergency air valves and the protection valve bleeds the low
pressure off as you suggest, then one could use either a leak detector
or soapy water (or for that matter, stretch a balloon on the top of the
valve which would expand slowly) to determine if the leak is from one of
the emergency air valves.
I can say this with carnal knowledge; the overnight test I previously
mentioned does work for a leaking main air valve.
Dennis
A. Dennis Savarese
334-285-6263
334-546-8182 (cell)
Skype: Yakguy1
www.yak-52.com
On 9/7/2011 5:52 AM, Rob Rowe wrote:
> --> Yak-List message posted by: "Rob Rowe"<yak-list@robrowe.plus.com>
>
> Dennis / Bill,
>
> Believe the protection valve Bill enquired about is the one located under the
starboard side of the front cockpit seat (YAK-52).
>
> Its vents the emergency air line (between the tap(s) and gear shuttle valves
/ uplocks) to atmosphere below 5 kgf/cm2 line pressure, to stop MINOR leaks from
the taps or shuttle valve 'peas' interfering with normal gear operation.
>
> For that very reason if you need to operate the emergency air system for real
then open the tap quickly and fully to make sure the protection valve snaps shut
(>5 kgf/cm2), otherwise you'll just waste the precious 3 litres reserve air
ventilating the P1's derriere! Keeping in mind, having lowered the gear, you
may well need what emergency air is left to also operate the brakes post landing.
>
> Similarly the overnight air tap leak test suggested will probably be inconclusive
for a YAK-52 because the air will most likely have been dumped externally
by the protection valve as
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=351640#351640
>
>
Message 6
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| Subject: | Re: Low Emergency Air Pressure |
Thanks Mark;
Another reminder that one can not assume any particular similarity
between the various models.
Walt
----- Original Message -----
From: Yak Pilot
To: yak-list@matronics.com
Sent: Wednesday, September 07, 2011 7:05 AM
Subject: Re: Yak-List: Low Emergency Air Pressure
No, it does not. The YAK-50 has four check valves. Two for air
input: One from the compressor, one from the external air. These come
together at the pressure relief valve and prevent reverse flow.
Out of the pressure relief valve you go to a "T" connector which feeds
an air strainer. The output of the air strainer, goes to another "T"
connector where there are two more check valves. Top one goes to
emergency air bottle, bottom one goes to main air bottle. Both go
DIRECTLY to the bottles. The air shut off valve in the cockpit does not
control air INPUT in any way to either bottle. It only controls air
output.
Mark Bitterlich
From: Walter Lannon <wlannon@persona.ca>
To: yak-list@matronics.com
Sent: Wednesday, September 7, 2011 12:30 AM
Subject: Re: Yak-List: Low Emergency Air Pressure
On the CJ if you wish to charge the emergency tank only, for example
with nitrogen rather than air simply leave the main air valve closed.
Probably applies to the Yak 50 as well
Walt
----- Original Message -----
From: Brian Lloyd
To: yak-list@matronics.com
Sent: Tuesday, September 06, 2011 3:09 PM
Subject: Re: Yak-List: Low Emergency Air Pressure
On Tue, Sep 6, 2011 at 9:25 AM, Yak Pilot <yakplt@yahoo.com> wrote:
On a YAK-52, the emergency bottle is not filled by the compressor.
Only by the external fill port.
On the YAK-50, the compressor charges both main and emergency.
Mark Bitterlich
Sorry Mark. I was thinking CJ6A. Emergency side is filled from the
compressor.
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics
.com/Navigator?Yak-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
et=_blank rel=nofollow>http://www.matronics.com/Navigator?Yak-List
=nofollow>http://forums.matronics.com
blank rel=nofollow>http://www.matronics.com/contribution
Message 7
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| Subject: | Re: Low Emergency Air Pressure |
Brian, I am not sure how you could away with any of these check valves and
keep system isolation.- You have two input air sources, and you have two
bottles.- Each air input needs to be isolated from each other and each bo
ttle needs to be isolated from each other.- How could you get away with l
ess? =0A=0A=0AMark=0A=0A=0AFrom: Brian Lloyd <brian@lloyd.com>=0ATo: yak-li
st@matronics.com=0ASent: Wednesday, September 7, 2011 10:57 AM=0ASubject: R
e: Yak-List: Low Emergency Air Pressure=0A=0A=0A=0AHas anyone else noticed
that there are a lot more check valves in our airplanes than are needed to
ensure system integrity after a partial failure? While helping Dennis Nicks
on troubleshoot an-intermittent-problem with the pneumatic system in hi
s CJ it was pretty obvious that I could replace several of the check valves
with straight pipe and it would have no effect on either the normal operat
ion or how the system would fail if it was breached at various places. And
I suspect that pieces of straight pipe are less likely to fail and cause pr
oblems than the various unnecessary check valves.=0A=0A=0AI am thinking tha
t, right after removing and throwing away the arcane and unnecessary comple
xity of the electrical system, we could probably to do the same for much of
the pneumatic system as well. :-)=0A=0A-- =0ABrian Lloyd, WB6RQN/J79BPL=0A
3191 Western Dr.=0ACameron Park, CA 95682=0Abrian@lloyd.com=0A+1.767.617.13
65 (Dominica)=0A+1.916.877.5067 (USA)
Message 8
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| Subject: | Re: Low Emergency Air Pressure |
=0A=0AIt always surprises me to see the differences between the YAK-50 and
52, and then turn right around and find exact matches with the CJ-6.- Esp
ecially with the actual parts themselves.- =0A-=0AMark=0A-=0AFrom: Wa
lter Lannon <wlannon@persona.ca>=0ATo: yak-list@matronics.com=0ASent: Wedne
sday, September 7, 2011 11:41 AM=0ASubject: Re: Yak-List: Low Emergency Air
Pressure=0A=0A=0AThanks Mark;=0AAnother reminder that one can not assume a
ny particular similarity between the various models.=0AWalt-
Message 9
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| Subject: | Re: Low Emergency Air Pressure |
On Wed, Sep 7, 2011 at 9:37 AM, Yak Pilot <yakplt@yahoo.com> wrote:
>
> It always surprises me to see the differences between the YAK-50 and 52,
> and then turn right around and find exact matches with the CJ-6. Especially
> with the actual parts themselves.
>
The Chinese never throw anything away. They just keep using it forever. And
they never let anyone else's work evade their eyes either. ;-)
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
Message 10
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| Subject: | Re: Low Emergency Air Pressure |
On Wed, Sep 7, 2011 at 9:35 AM, Yak Pilot <yakplt@yahoo.com> wrote:
> Brian, I am not sure how you could away with any of these check valves and
> keep system isolation. You have two input air sources, and you have two
> bottles. Each air input needs to be isolated from each other and each
> bottle needs to be isolated from each other. How could you get away with
> less?
>
Maybe you need to look at the CJ6A pneumatic system, which is what I was
dealing with when troubleshooting and making my observations.
The problem is, while the check valves ostensibly provide isolation, they
don't really because there really is only a single source of pressure in the
entire system. So a failure in any subsystem results in depressurization of
the entire system. Yes, it is possible that, if you already have the gear
down some of those check-valves might hold the pressure in the down-circuit
there is no separate storage in the gear circuit to allow you to still put
the gear down. So the backup/emergency system really is the only solution,
thus making almost all the check-valves in main system superfluous.
You can repeat my thought experiment. Take the pneumatic system schematic,
imagine system breaches at different points, and then see what the effect is
on the rest of the system. Now repeat the process while removing various
check valves from the schematic. I think you will find that in VERY few
cases do the check valves allow the rest of the system to continue to work.
The only real answer is the emergency system.
OTOH, I also got see how check valves fail. If not properly maintained (and
a lot of them are not properly maintained) the carbon-steel springs corrode,
fail, and spread pieces of rust through the system. The funny thing is, even
with the failed check valves, the system operates normally, except when the
rust gets into things like valves and actuators. ;-)
Now it has been awhile since I looked at the schematic for the Yak-52
pneumatic system so perhaps my points are less valid for that system.
But never underestimate the power of KISS. Remember, when something isn't
there it can't fail.
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
Message 11
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| Subject: | Re: Low Emergency Air Pressure |
Hi Brian,
Interesting thought exercise ... the YAK-52 designers seem to have beaten us to
it, in as much as there are fewer pneumatic check valves (NRVs) than those of
its near & far relations.
Skip this next bit if you're easily bored ;-)
Air charging NRVs:
Main - failure dumps main system pressure overboard [essential]
Reserve - ditto for emergency air [essential]
Compressor (feeds main) - failure dumps system pressure on opening snot valve [highly
desirable!]
Protection Valve - needed to EASILY depressurise emergency system after use (you
could just keep pumping the brakes though) & stop seepage operating emergency
gear systems [highly desirable]
Brake Valve feed NRVs:
Main - allows use of emergency air in event of main air failure [essential]
Reserve - failure cross-feeds air into emergency systems on operating brakes ...
another reason why the Protection Valve is fitted [highly desirable]
Air 'Off' Start Protection (UK mandated mod) - helps prevent engine start with
air off (so no brakes either) by preventing gear system back pressure from being
used to start engine. [useful, but superfluous]
What surprises me though is how many ways they've found to use the same components,
plumbed in different configurations, to perform ostensibly the same operational
function across these aircraft ... an area where system standardisation
would really have paid dividends from a pilot's perspective.
Brgds, Rob R
brian(at)lloyd.com wrote:
>
>
> Maybe you need to look at the CJ6A pneumatic system, which is what I was dealing
with when troubleshooting and making my observations.
>
>
> The problem is, while the check valves ostensibly provide isolation, they don't
really because there really is only a single source of pressure in the entire
system. So a failure in any subsystem results in depressurization of the entire
system ... So the backup/emergency system really is the only solution, thus
making almost all the check-valves in main system superfluous.
>
>
> You can repeat my thought experiment. Take the pneumatic system schematic, imagine
system breaches at different points, and then see what the effect is on
the rest of the system. Now repeat the process while removing various check valves
from the schematic. I think you will find that in VERY few cases do the check
valves allow the rest of the system to continue to work. The only real answer
is the emergency system.
>
> ... Now it has been awhile since I looked at the schematic for the Yak-52 pneumatic
system so perhaps my points are less valid for that system.
>
> ...
> --
> Brian Lloyd, WB6RQN/J79BPL
> 3191 Western Dr.
> Cameron Park, CA 95682
> brian@lloyd.com (brian@lloyd.com)
> +1.767.617.1365 (Dominica)
> +1.916.877.5067 (USA)
>
>
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=351680#351680
Message 12
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| Subject: | Re: Low Emergency Air Pressure |
In the case of my Aircraft (yak-18t) it turned out to be a pinhole leak in the
bottom of the emergency bottle through the weld - had to purchase a new bottle
from WLAC in the UK. Talking to the local CFI the other day reveals that a similar
leak found in 2 other a/c on the field, one a yak-52 and the other a CJ6!
One other thing to check. Cheers, Phil.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=351681#351681
Message 13
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| Subject: | Re: Low Emergency Air Pressure |
Too many airplanes to discuss at once Brian.- YAK-52 is not the same as Y
AK-50.- CJ-6 is yet another topic.-- The check valves in the 50 syste
m make perfect sense.- Emergency bottle and Main bottle are resevoirs and
thus are sources unto themselves.- This becomes a discussion of semantic
s and that is not something I am interested in going into honestly.- In f
light, the compressor is actually a renewable source not a single source.
- The check valves in the 50 design prevent any single source of failure
from preventing gear extension.- Removing any of them will remove that fe
ature, which is obviously to be avoided.- I am not an expert on the CJ-6
or the YAK-52, so I can't speak to those topics.- I believe the YAK-50 de
sign is excellent and does it's job perfectly, and I do not believe it can
be done any better with removal of any components.- =0A-=0AJust saying.
- =0A-=0AMark=0A-=0A=0AFrom: Brian Lloyd <brian@lloyd.com>=0ATo: yak-
list@matronics.com=0ASent: Wednesday, September 7, 2011 1:01 PM=0ASubject:
Re: Yak-List: Low Emergency Air Pressure=0A=0A=0A=0A=0A=0AOn Wed, Sep 7, 20
11 at 9:35 AM, Yak Pilot <yakplt@yahoo.com> wrote:=0A=0ABrian, I am not sur
e how you could away with any of these check valves and keep system isolati
on.- You have two input air sources, and you have two bottles.- Each ai
r input needs to be isolated from each other and each bottle needs to be is
olated from each other.- How could you get away with less?=0A=0AMaybe you
need to look at the CJ6A pneumatic system, which is what I was dealing wit
h when troubleshooting and making my observations.=0A=0AThe problem is, whi
le the check valves ostensibly provide isolation, they don't really because
there really is only a single source of pressure in the entire system. So
a failure in any subsystem results in depressurization of the entire system
. Yes, it is possible that, if you already have the gear down some of those
check-valves might hold the pressure in the down-circuit there is no separ
ate storage in the gear circuit to allow you to still put the gear down. So
the backup/emergency system really is the only solution, thus making almos
t all the check-valves in main system superfluous.-=0A=0AYou can repeat m
y thought experiment. Take the pneumatic system schematic, imagine system b
reaches at different points, and then see what the effect is on the rest of
the system. Now repeat the process while removing various check valves fro
m the schematic. I think you will find that in VERY few cases do the check
valves allow the rest of the system to continue to work. The only real answ
er is the emergency system.=0A=0AOTOH, I also got see how check valves fail
. If not properly maintained (and a lot of them are not properly maintained
) the carbon-steel springs corrode, fail, and spread pieces of rust through
the system. The funny thing is, even with the failed check valves, the sys
tem operates normally, except when the rust gets into things like valves an
d actuators. ;-)=0A=0ANow it has been awhile since I looked at the schemati
c for the Yak-52 pneumatic system so perhaps my points are less valid for t
hat system.=0A=0ABut never underestimate the power of KISS. Remember, when
something isn't there it can't fail.=0A-- =0ABrian Lloyd, WB6RQN/J79BPL=0A3
191 Western Dr.=0ACameron Park, CA 95682=0Abrian@lloyd.com=0A+1.767.617.136
5 (Dominica)=0A+1.916.877.5067 (USA)
Message 14
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| Subject: | Re: Low Emergency Air Pressure |
On Wed, Sep 7, 2011 at 12:15 PM, Rob Rowe <yak-list@robrowe.plus.com> wrote:
>
> Hi Brian,
>
> Interesting thought exercise ... the YAK-52 designers seem to have beaten
> us to it, in as much as there are fewer pneumatic check valves (NRVs) than
> those of its near & far relations.
>
That well could be. It has been quite some time since I have studied the
Yak-52 pneumatic diagram.
>
> Skip this next bit if you're easily bored ;-)
>
No worries. I love the details.
>
> Air charging NRVs:
> Main - failure dumps main system pressure overboard [essential]
> Reserve - ditto for emergency air [essential]
> Compressor (feeds main) - failure dumps system pressure on opening snot
> valve [highly desirable!]
>
> Protection Valve - needed to EASILY depressurise emergency system after use
> (you could just keep pumping the brakes though) & stop seepage operating
> emergency gear systems [highly desirable]
>
Are you talking about a check valve or the shuttle valve that is used to
automatically select system source (main or emergency)?
In many cases the problem is not one of preventing flow back into an
upstream [sub]system that has failed but that forward flow into a failed
subsystem still drains the source, making the overall pneumatic systems
unusable.
>
> Brake Valve feed NRVs:
> Main - allows use of emergency air in event of main air failure [essential]
> Reserve - failure cross-feeds air into emergency systems on operating
> brakes ... another reason why the Protection Valve is fitted [highly
> desirable]
>
> Air 'Off' Start Protection (UK mandated mod) - helps prevent engine start
> with air off (so no brakes either) by preventing gear system back pressure
> from being used to start engine. [useful, but superfluous]
>
Yes. That sort of thing introduces an additional point of failure that is
hard to detect and gains you very little.
But you may find that two or more of these valves that you have listed as
essential, can have their functions fulfilled by a single,
strategically-place check valve.
What surprises me though is how many ways they've found to use the same
> components, plumbed in different configurations, to perform ostensibly the
> same operational function across these aircraft ... an area where system
> standardisation would really have paid dividends from a pilot's perspective.
>
That is also true.
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
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| Subject: | Re: Low Emergency Air Pressure |
On Wed, Sep 7, 2011 at 12:36 PM, Yak Pilot <yakplt@yahoo.com> wrote:
> Too many airplanes to discuss at once Brian. YAK-52 is not the same as
> YAK-50. CJ-6 is yet another topic. The check valves in the 50 system make
> perfect sense. Emergency bottle and Main bottle are resevoirs and thus are
> sources unto themselves. This becomes a discussion of semantics and that is
> not something I am interested in going into honestly. In flight, the
> compressor is actually a renewable source not a single source. The check
> valves in the 50 design prevent any single source of failure from preventing
> gear extension. Removing any of them will remove that feature, which is
> obviously to be avoided. I am not an expert on the CJ-6 or the YAK-52, so I
> can't speak to those topics. I believe the YAK-50 design is excellent and
> does it's job perfectly, and I do not believe it can be done any better with
> removal of any components.
>
I don't doubt your word a bit. My comments were pretty much limited to the
CJ6A since I have no knowledge of the Yak-50 pneumatic system and my
knowledge of the Yak-52 is old.
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
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Anyone out there have any contract info for Dave Enrico?
208-709-1688 rings steady fast busy signal??
skypilot@silverstar.com is also TU.
Best to all,
Doug
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| Subject: | Re: Low Emergency Air Pressure |
Hi all,
dont forget to check the pipe / hose which connects the emergency bottle with the
pressure gauge in the cockpit. When this fails you loose all air. We had a
tiny leak in this particular hose of our 18 T as no one had changed it for ages.
Good luck on this one !
Cheers
Vic
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=351693#351693
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| Subject: | Re: Low Emergency Air Pressure |
Old Chinese saying - "Why reinvent wheel? It work good. Besides spend
less time at drawing board."
Pappy
In a message dated 9/7/2011 12:39:44 P.M. Eastern Daylight Time,
yakplt@yahoo.com writes:
It always surprises me to see the differences between the YAK-50 and 52,
and then turn right around and find exact matches with the CJ-6. Especially
with the actual parts themselves.
Mark
From: Walter Lannon <wlannon@persona.ca>
Sent: Wednesday, September 7, 2011 11:41 AM
Subject: Re: Yak-List: Low Emergency Air Pressure
Thanks Mark;
Another reminder that one can not assume any particular similarity between
the various models.
Walt
(http://www.matronics.com/Navigator?Yak-List)
(http://www.matronics.com/contribution)
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| Subject: | Re: Low Emergency Air Pressure |
Thanks to all for the great suggestions.
Dennis, I filled it externally and sprayed soapy water... no leak at the fill
port. Watched it for over an hour, bled the brakes as you suggested, no "woosh",
and no drop on the guages during that time either. I won't be able to check
it again until Friday. The leak detector sounds like a must have with these beast,
so it is on the way also. Thanks again.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=351704#351704
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| Subject: | Re: Low Emergency Air Pressure |
My CJ-6 was born without up locks. I just need to keep the gear handle up
else the gear will eventually fall down without any air pressure - if I
happen to turn off the air tank or lose the compressor. I like it like that.
Few points of failure.
Speaking there of - I removed the instructor's cut out valve on the rear
control stick. I removed all the hoses and pipes from the QS1 to the QS2
and simply run a tube directly from one to the another. That could have been
at least 6 points failure/leaks.
One thing that has also helped me, is going to stainless steel parts when I
can find them. Springs especially.
Jim "Pappy" Goolsby
In a message dated 9/7/2011 1:08:01 P.M. Eastern Daylight Time,
brian@lloyd.com writes:
On Wed, Sep 7, 2011 at 9:35 AM, Yak Pilot <_yakplt@yahoo.com_
(mailto:yakplt@yahoo.com) > wrote:
Brian, I am not sure how you could away with any of these check valves and
keep system isolation. You have two input air sources, and you have two
bottles. Each air input needs to be isolated from each other and each
bottle needs to be isolated from each other. How could you get away with less?
Maybe you need to look at the CJ6A pneumatic system, which is what I was
dealing with when troubleshooting and making my observations.
The problem is, while the check valves ostensibly provide isolation, they
don't really because there really is only a single source of pressure in the
entire system. So a failure in any subsystem results in depressurization
of the entire system. Yes, it is possible that, if you already have the gear
down some of those check-valves might hold the pressure in the
down-circuit there is no separate storage in the gear circuit to allow you to
still
put the gear down. So the backup/emergency system really is the only
solution, thus making almost all the check-valves in main system superfluous.
You can repeat my thought experiment. Take the pneumatic system schematic,
imagine system breaches at different points, and then see what the effect
is on the rest of the system. Now repeat the process while removing various
check valves from the schematic. I think you will find that in VERY few
cases do the check valves allow the rest of the system to continue to work.
The only real answer is the emergency system.
OTOH, I also got see how check valves fail. If not properly maintained
(and a lot of them are not properly maintained) the carbon-steel springs
corrode, fail, and spread pieces of rust through the system. The funny thing is,
even with the failed check valves, the system operates normally, except
when the rust gets into things like valves and actuators. ;-)
Now it has been awhile since I looked at the schematic for the Yak-52
pneumatic system so perhaps my points are less valid for that system.
But never underestimate the power of KISS. Remember, when something isn't
there it can't fail.
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
_brian@lloyd.com_ (mailto:brian@lloyd.com)
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
(http://www.matronics.com/Navigator?Yak-List)
http://www.matronics.com/contribution)
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| Subject: | Re: Low Emergency Air Pressure |
Hi Brian
>
> Skip this next bit if you're easily bored ;-)
>
> No worries. I love the details.
>
Me too.
>
> Air charging NRVs:
> Main - failure dumps main system pressure overboard [essential]
> Reserve - ditto for emergency air [essential]
> Compressor (feeds main) - failure dumps system pressure on opening snot valve
[highly desirable!]
>
> Protection Valve - needed to EASILY depressurise emergency system after use (you
could just keep pumping the brakes though) & stop seepage operating emergency
gear systems [highly desirable]
>
> Are you talking about a check valve or the shuttle valve that is used to automatically
select system source (main or emergency)?
>
NRV = check valve
Protection valve = specialist in-line device that vents both sides to atmosphere
below line pressure of 5 kgf/cm2
>
> In many cases the problem is not one of preventing flow back into an upstream
[sub]system that has failed but that forward flow into a failed subsystem still
drains the source, making the overall pneumatic systems unusable.
>
This is also true
>
> But you may find that two or more of these valves that you have listed as essential,
can have their functions fulfilled by a single, strategically-place check
valve.
>
Possibly ... just not probably in this case. The -52 approach appears to have been
to use as few check valves as possible & place them such that their likely
serviceability is brought to your attention during a pre-flight inspection.
IMHO I prefer this -52 design as while it may make any in-flight failure of greater
consequence, it is at least in terms of largely black & white remedial actions.
Rather than the shades of grey that may result from systems designed with
numerous embedded check valves whose serviceability is largely indeterminate
until something fails else where.
Guess this is where we came in ;-)
Brgds, Rob R
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=351712#351712
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| Subject: | Re: Low Emergency Air Pressure |
On Wed, Sep 7, 2011 at 6:55 PM, Rob Rowe <yak-list@robrowe.plus.com> wrote:
> > Are you talking about a check valve or the shuttle valve that is used to
> automatically select system source (main or emergency)?
> >
>
>
> NRV = check valve
>
> Protection valve = specialist in-line device that vents both sides to
> atmosphere below line pressure of 5 kgf/cm2
>
I don't recall any of those on the CJ6A.
> > In many cases the problem is not one of preventing flow back into an
> upstream [sub]system that has failed but that forward flow into a failed
> subsystem still drains the source, making the overall pneumatic systems
> unusable.
> >
>
>
> This is also true
>
>
> >
> > But you may find that two or more of these valves that you have listed as
> essential, can have their functions fulfilled by a single,
> strategically-place check valve.
> >
>
>
> Possibly ... just not probably in this case. The -52 approach appears to
> have been to use as few check valves as possible & place them such that
> their likely serviceability is brought to your attention during a pre-flight
> inspection.
>
That does seem to be different than the CJ6A
>
> IMHO I prefer this -52 design as while it may make any in-flight failure of
> greater consequence, it is at least in terms of largely black & white
> remedial actions. Rather than the shades of grey that may result from
> systems designed with numerous embedded check valves whose serviceability is
> largely indeterminate until something fails else where.
>
I agree completely.
>
> Guess this is where we came in ;-)
>
Indeed it is. :-)
--
Brian Lloyd, WB6RQN/J79BPL
3191 Western Dr.
Cameron Park, CA 95682
brian@lloyd.com
+1.767.617.1365 (Dominica)
+1.916.877.5067 (USA)
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