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Date: Sun, 04 Nov 2007 21:28:20 -0500
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From: "genemartin" <genemartin@enid.com>
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Subject: Re: [LML] Re: FW: [LML] LNC2 Hyd Chirp Alternative Mousetrap
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I have such a secret override switch...top secret unmarked don't ask =
don't tell.
Gene
  ----- Original Message -----=20
  From: Sky2high@aol.com=20
  To: lml@lancaironline.net=20
  Sent: Saturday, November 03, 2007 9:06 AM
  Subject: [LML] Re: FW: [LML] LNC2 Hyd Chirp Alternative Mousetrap


  In a message dated 11/2/2007 10:48:32 A.M. Central Daylight Time, =
LHenney@charter.net writes:
    Air is good if your breathing and bad if leaking into your brain.  =
OK, I'll go out and rebuild one this am and report back.  Oh, but wait, =
I guess the rebuild of the leaker will have an affect on our test.=20
  Larry,

  I love spirited discussions leading to one's spirit sipping spirits =
during contemplation of the metaphysical.  I thought more about all the =
problems reported over the years and the possible effect of air.  Let's =
see if we can work thru this by picking the system apart.  But first, I =
said you should only introduce air into the system as a test of your =
theory, not rebuild a cylinder. =20

  Air in cylinders=20

  4 of the six cylinders, those associated with the main gears and =
doors, can be eliminated because they are oriented horizontally with all =
ports pointed upward so the air will not remain in those actuators. =20

  The nose gear door cylinder, vertically oriented cannot hold much air =
in the bottom after extension because the air would have to fit in a =
donut cylinder volume 5/32 high with the inside 1/2" diameter and the =
outside 5/8 diameter - a volume of .017 cubic inches.  This space is =
inside of the extension piston stop that allows fluid to be passed in =
and out of the cylinder.  Upon retraction, even though the piston does =
not tightly reach the top, the fluid exit is at the top and air would be =
expelled.  The .017 ci of air could be trapped at the piston that is =
pushed in by the hi pressure retraction activity and the bubble could =
rise to the bottom of the piston.

  The nose gear cylinder is somewhat vertically oriented and the =
cylinder cannot hold any air in the bottom beyond the piston at full =
extension since it is stopped tightly against the forward bulkhead (if =
properly rigged).  However, retraction is limited by the external stop =
and the fluid exit is at the aft lower side of the cylinder.  I forgot =
to check how vertically oriented the cylinder gets on retraction, but =
let's say the whole remaining space can retain air.  That is a cylinder =
approximately 3/4" high with a diameter of 9/8" for a volume of about =
.75 cubic inches.  Of course, at retraction this pocket would not be =
under pressure since it is the other side of the piston that is under =
pressure.  So, it is on extension that some of this pocket could be =
compressed although it would seem that some of the air would come out at =
each retraction. =20

  Air in lines

  There also are short pieces of Easton flexible line that feeds into =
1/4" hard Al lines. Let's discuss how much volume these lines can hold.  =
For the Easton line (I could not find a sample), assume it has an =
interior cross section of 1/4".   That is 20.37 inches of tube per 1 =
cubic inch of fluid volume.  The 1/4" hard lines have a wall thickness =
of .035, thus the interior diameter is .18" or 39.3 inches of tube per =
cubic inch of volume.

  Door actuators move about .9 ci of fluid in when extended and .7 ci in =
when retracted.  The nose gear cylinder (I forgot to measure the length, =
say 4.5" of movement) moves about 4.5 ci of fluid in when extended and 4 =
ci in when retracted.

  Since the opening of doors requires fluid passage thru sequence =
valves, those lines might not be completely cleared because of the hard =
line length may hold more fluid than is transferred to and from the =
actuator.  One could consider a small bubble remaining in those lines.  =
The retraction side moves more fluid thru shorter lines so it is less =
likely that air is trapped in those lines.  The large actuators move =
much more fluid and it is hard to believe any air remaining in those =
lines.

  Air Elsewhere

  The dump valve body can't hold air once it has been opened.  Perhaps =
the teed vertical lines leading to the pressure switches retain air.

  Gas Laws

  For those that suspect that heated trapped air raises the system =
pressure quite a bit should note that when the volume is held constant, =
the pressure increases as the temperature ratio, in Kelvin, increases.  =
A rise from 50F to 80F is 299K/283K or approximately a 5% increase - =
Hardly accounting for a rise of several hundred psi.  I await an =
engineer to evaluate effects of the differing expansion factors for =
aluminum, Easton lines, cylinders and the fluid itself.

  On the converse, if the air is compressed (so far this looks like a =
problem that is possible solely on the down side at the nose gear =
actuator), I would finally have to agree that more volume of fluid under =
pressure from the air would have to pass through the system leak to =
activate the pressure switch than that from incompressible fluid on its =
own. Maybe.  That these air pockets may work themselves out so that the =
chirp rate increases is interesting.

  So I can see where an accumulator could delay pump activation.  No =
problem as long as other parts of the system are working properly.  It =
is hard to see where any air bubbles could influence the up side of the =
system other than those trapped in the sequence valve circuits.

  ----

  As to some of the other contentions.................

  You said: "You're an electrics guy.  Does that little chirp every 20 =
seconds not bother you just a little?  You know, arcing and corrosion in =
the relays, airborne fire, alternator shorting, etc?"

  You are correct, the wiring is correct.  Thus, arcing and corrosion =
are not a problem - intermittent relays are operating intermittently .  =
Airborne fire and alternator shorting are not a problem from the pump =
blips for the small percentage of block time that the gear is down, nor =
is anything else associated with the hydro-electric gear system.  =
However, "etc." does indeed bother me, although it is not related to =
this situation.

  One of the risks you may add is that the accumulator on the high =
pressure side may lock up the low pressure side if you have a failure =
like that sometimes described by other Lancairites and not yet fully =
understood.  This is the case where opening the dump valve does not =
resolve the peculiarly built system pressure present on both sides and =
that trips both pressure switches.  There may be an electrical solution =
- perhaps bring duplicate wires from the pressure switches forward to =
secret over ride switches operable by the captain.  Forced activation of =
the pump may free the lockup if it is the case of a stuck shuttle valve. =
 Of course the captain's hearing has to be good enough to perform an =
"undo" if the pump is straining as the captain becomes the acting =
pressure switch.

  Good Luck,

  Scott Krueger AKA Grayhawk
  Lancair N92EX IO320 SB 89/96
  Aurora, IL (KARR)

  Darwinian culling phrase: Watch This!





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<DIV>I have such a secret override switch...top secret unmarked don't =
ask don't=20
tell.</DIV>
<DIV>Gene</DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A title=3DSky2high@aol.com =
href=3D"mailto:Sky2high@aol.com">Sky2high@aol.com</A>=20
  </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dlml@lancaironline.net=20
  href=3D"mailto:lml@lancaironline.net">lml@lancaironline.net</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Saturday, November 03, =
2007 9:06=20
  AM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [LML] Re: FW: [LML] =
LNC2 Hyd=20
  Chirp Alternative Mousetrap</DIV>
  <DIV><BR></DIV><FONT id=3Drole_document face=3DArial color=3D#000000 =
size=3D2><FONT=20
  id=3Drole_document face=3DArial color=3D#000000 size=3D2>
  <DIV>
  <DIV>In a message dated 11/2/2007 10:48:32 A.M. Central Daylight Time, =
<A=20
  href=3D"mailto:LHenney@charter.net">LHenney@charter.net</A> =
writes:</DIV>
  <BLOCKQUOTE=20
  style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT=20
    style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 =
size=3D2>
    <DIV><SPAN class=3D859535212-02112007>Air is good if your breathing =
and bad if=20
    leaking into your brain.&nbsp; OK, I'll go out and rebuild one this =
am and=20
    report back.&nbsp; Oh, but wait, I guess the rebuild of the leaker =
will have=20
    an affect on our test.&nbsp;</SPAN></DIV></FONT></BLOCKQUOTE></DIV>
  <DIV></DIV>
  <DIV>Larry,</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>I love spirited discussions leading to one's spirit sipping =
spirits=20
  during contemplation&nbsp;of the metaphysical.&nbsp; I thought more =
about all=20
  the problems reported over the years&nbsp;and the possible effect of=20
  air.&nbsp; Let's see if we can work thru this by picking the system=20
  apart.&nbsp; But first, I said you should only introduce air into the =
system=20
  as a test of your theory, not rebuild a cylinder.&nbsp;&nbsp;</DIV>
  <DIV>&nbsp;</DIV>
  <DIV><U>Air in cylinders </U></DIV>
  <DIV>&nbsp;</DIV>
  <DIV>4 of the six cylinders, those associated with the main gears and =
doors,=20
  can be eliminated because they are oriented horizontally&nbsp;with all =
ports=20
  pointed upward so the air will not remain in those actuators.&nbsp; =
</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>The nose gear door cylinder, vertically oriented cannot hold much =
air in=20
  the bottom after extension because the air would have to fit in a =
donut=20
  cylinder volume&nbsp;5/32 high with the inside 1/2" diameter and the =
outside=20
  5/8 diameter - a volume of .017 cubic inches.&nbsp; This space is =
inside of=20
  the extension piston stop that allows fluid to be passed in and out of =
the=20
  cylinder.&nbsp; Upon retraction, even though the piston does not =
tightly reach=20
  the top, the fluid exit is at the top and air would be expelled.&nbsp; =
The=20
  .017 ci of air could be trapped at the piston that is pushed in by the =
hi=20
  pressure retraction activity and the bubble could rise to the bottom =
of the=20
  piston.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>The nose gear cylinder is somewhat vertically oriented and the =
cylinder=20
  cannot hold any air in the bottom beyond the piston&nbsp;at full =
extension=20
  since it is stopped tightly against the forward bulkhead (if properly=20
  rigged).&nbsp; However, retraction is limited by the external stop and =
the=20
  fluid exit is at the aft lower side of the cylinder.&nbsp; I forgot to =
check=20
  how vertically oriented the cylinder gets on retraction, but let's say =
the=20
  whole remaining&nbsp;space can retain air.&nbsp; That is a cylinder=20
  approximately 3/4" high with a diameter of 9/8" for a volume of about =
.75=20
  cubic inches.&nbsp; Of course, at retraction this pocket would not be =
under=20
  pressure since it is the other side of the piston that is under=20
  pressure.&nbsp; So, it is on extension that some of this pocket could =
be=20
  compressed although it would seem that some of the air would come out =
at each=20
  retraction.&nbsp; </DIV>
  <DIV>&nbsp;</DIV>
  <DIV><U>Air in lines</U></DIV>
  <DIV>&nbsp;</DIV>
  <DIV>There&nbsp;also are short pieces of Easton flexible line that =
feeds into=20
  1/4" hard&nbsp;Al lines.&nbsp;Let's discuss how much volume these =
lines can=20
  hold.&nbsp; For the Easton line (I could not find a sample), assume it =
has an=20
  interior&nbsp;cross section of 1/4".&nbsp; &nbsp;That is 20.37 inches =
of tube=20
  per 1 cubic inch of fluid volume.&nbsp; The 1/4" hard lines have a =
wall=20
  thickness of .035, thus the interior diameter is .18" or 39.3 inches =
of tube=20
  per cubic inch of volume.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>Door actuators move about .9 ci of fluid in when extended and .7 =
ci in=20
  when retracted.&nbsp; The nose gear cylinder (I forgot to measure the =
length,=20
  say 4.5" of movement) moves about 4.5&nbsp;ci of fluid in when =
extended and 4=20
  ci in when retracted.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>Since the opening of doors requires fluid passage thru sequence =
valves,=20
  those lines might not be completely cleared because of the hard line =
length=20
  may hold more fluid than is transferred to and from the =
actuator.&nbsp; One=20
  could&nbsp;consider a small bubble&nbsp;remaining&nbsp;in those =
lines.&nbsp;=20
  The retraction side moves more fluid thru shorter lines so it is less =
likely=20
  that air is trapped&nbsp;in those lines.&nbsp; The large actuators =
move much=20
  more fluid and it is hard to believe any air remaining in those =
lines.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV><U>Air Elsewhere</U></DIV>
  <DIV><U></U>&nbsp;</DIV>
  <DIV>The dump&nbsp;valve body can't hold air once it has been =
opened.&nbsp;=20
  Perhaps the teed vertical lines leading to the pressure switches =
retain=20
  air.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV><U>Gas Laws</U></DIV>
  <DIV><U></U>&nbsp;</DIV>
  <DIV>For those that suspect that heated trapped air raises the system =
pressure=20
  quite a bit should note that when the volume is held constant, the =
pressure=20
  increases as the temperature ratio, in Kelvin,&nbsp;increases.&nbsp; A =
rise=20
  from 50F to 80F is 299K/283K or approximately a 5% increase - Hardly=20
  accounting for a rise of several hundred psi.&nbsp; I await an =
engineer to=20
  evaluate effects of the differing expansion factors for aluminum, =
Easton=20
  lines, cylinders and the fluid itself.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>On the converse, if the air is compressed (so far this looks like =
a=20
  problem that is possible solely on the&nbsp;down side at the&nbsp;nose =
gear=20
  actuator), I would finally have to agree that more volume of fluid =
under=20
  pressure from the&nbsp;air&nbsp;would have to pass through&nbsp;the =
system=20
  leak to activate the pressure switch than that from incompressible =
fluid on=20
  its own. Maybe.&nbsp; That these air&nbsp;pockets may work themselves =
out so=20
  that the chirp rate increases is interesting.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>So I can see where an accumulator could delay pump =
activation.&nbsp; No=20
  problem as long as other parts of the system are working =
properly.&nbsp; It is=20
  hard to see where any air bubbles could influence the up side of the =
system=20
  other than those trapped&nbsp;in the sequence valve circuits.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>----</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>As to some of the&nbsp;other contentions.................</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>You said: "You're an electrics guy.&nbsp; Does that little chirp =
every 20=20
  seconds not bother you just a little?&nbsp; You know, arcing and =
corrosion in=20
  the relays, airborne fire, alternator shorting, etc?"</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>You are correct, the wiring is correct.&nbsp; Thus, arcing and =
corrosion=20
  are not a problem - intermittent&nbsp;relays are operating =
intermittently=20
  .&nbsp; Airborne fire and alternator shorting are not a problem from =
the pump=20
  blips for the small percentage of&nbsp;block time that&nbsp;the gear =
is down,=20
  nor&nbsp;is anything else associated with the hydro-electric gear=20
  system.&nbsp; However, "etc." does indeed bother me, although it is =
not=20
  related to this situation.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>One of the risks you may add is that the accumulator on the high =
pressure=20
  side may lock up the low pressure side if you have a failure like that =

  sometimes described by other Lancairites and not yet fully =
understood.&nbsp;=20
  This is the case where opening the dump valve does not resolve the =
peculiarly=20
  built&nbsp;system pressure present on both sides and&nbsp;that trips =
both=20
  pressure switches.&nbsp; There may be an electrical solution -=20
  perhaps&nbsp;bring duplicate wires from the pressure switches forward =
to=20
  secret over ride switches operable by the captain.&nbsp; Forced =
activation of=20
  the pump may free the lockup if it is&nbsp;the case of a stuck shuttle =

  valve.&nbsp; Of course&nbsp;the captain's&nbsp;hearing has to be good =
enough=20
  to perform an "undo" if the pump is straining as the =
captain&nbsp;becomes the=20
  acting pressure switch.</DIV>
  <DIV>&nbsp;</DIV>
  <DIV>Good Luck,</DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT lang=3D0 face=3DArial size=3D2 PTSIZE=3D"10" =
FAMILY=3D"SANSSERIF">Scott=20
  Krueger AKA Grayhawk<BR>Lancair N92EX IO320 SB 89/96<BR>Aurora, IL=20
  (KARR)<BR><BR>Darwinian culling phrase: Watch=20
  This!</FONT></DIV></FONT></FONT><BR><BR><BR>
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