REFLECTOR: Pressure testing

David Ullman ullman at robustdecisions.com
Sat Apr 7 08:14:48 CDT 2007


Larry and I spoke about this a couple of weeks ago.  I am still months out
from doing this test, but decided to look into how I might do it.  First
question is, what pressure?  Since the plane is rated at 6gs, taking the
density of fuel and doing some algebra shows that the max pressure exerted
is about 1.5psi.  No need to go higher than this.  To get this pressure with
a simple U-tube manometer requires some care so you don't get water in the
tank.  As you compress 35 gallons of air 1.0 psi you need to make up 2.3
gallons.  So the best way to do this, as best I can figure, is build a
U-tube with a 5 gallon sealed paint bucket at the bottom (paint stores sell
them cheap).  The paint bucket is there to provide the needed volume of
compressed air.  Have one tube come in very near the bottom of the bucket
(the fill tube) and the other out the top (going to the fuel tank).  The
fill tube needs to stick straight up about 5' and the other tube should go
up at least that far on its way to the tank (ensures no water in the tank).
Pour water in the fill tube.  For every 27" the water rises in the fill tube
you get 1 psi of pressure in the tank.

Is this overkill?

Note.  I have just decided to go to Oshgosh (the misspelling is on purpose
because I expect to say "gosh" or something similar, a lot).  I hope to meet
many of you there and count me in on any events that get planned.



-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of reflector-request at tvbf.org
Sent: Friday, April 06, 2007 2:31 PM
To: reflector at tvbf.org
Subject: Reflector Digest, Vol 35, Issue 16

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Today's Topics:

   1. Re:  RG Questions (Laurence Coen)
   2. Re:  Leak testing Fuel Strake (Joe Ewen)
   3.  Fuel Leak (Milehitaz at aol.com)
   4. Re:  Fuel Leak (PUSHERPILOT at wmconnect.com)
   5. Re:  Fuel Leak (Darrell & Nora Kufalk)
   6. Re:  South Houston (Christopher Barber)


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Message: 1
Date: Fri, 6 Apr 2007 05:28:26 -1200
From: "Laurence Coen" <lwcoen at hotmail.com>
Subject: Re: REFLECTOR: RG Questions
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Message-ID: <BAY135-DAV1592A04C9D704030B3930AD3640 at phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"

I'll second that.  My Franklin engine makes extensive use of "Nylock" nuts
to hold the case together.

Larry Coen
N136LC
  ----- Original Message ----- 
  From: Ron Brown 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Friday, April 06, 2007 2:32 AM
  Subject: Re: REFLECTOR: RG Questions


  "There should be no fiber lock nuts in the engine compartment"

  I disagree with this statement. You don't want them on any critical
applications - for certain.  However, my I/A buddy with many years of
experience doesn't feel this is a problem.  If you are finding nuts that are
loosing their tension - then yes replace them with crush nuts or castled
nuts and cotter pins.  But the blanket statement of no nylocks or fiber lock
nuts in the engine compartment is not accurate.  

  After 4 years and nearly 350 hours, I have seen no problems with any of
the nylocks in my engine compartment.

  My opinion!

  Ronnie


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Message: 2
Date: Fri, 6 Apr 2007 13:03:57 -0400
From: "Joe Ewen" <jewen at comporium.net>
Subject: Re: REFLECTOR: Leak testing Fuel Strake
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Message-ID: <009e01c7786d$909e2480$6605a8c0 at cooleygroup.local>
Content-Type: text/plain; charset="iso-8859-1"

Larry,
I would be concerned putting even 2 to 3 pisg into the strake.  When I
tested my strakes, I connected a balloon to the fuel side plumbing and a
hose to the vent line.  The fuel cap will not be airtight, I sealed the caps
with a wide making tape (wide enough to completely cover the cap without any
seams.  multiple layers of masking tape will allow a pin hole and make it
look like you have a leak.)  I then blew into the vent line until the
balloon was inflated to the desired level.  I did this in the early
afternoon and was concerned near nightfall when the balloon was shriveled,
but I did some calculations using the Ideal Gas Law and found that the
temperature change was sufficient to deflate the balloon.  I waited until
the next day when the temp was approximately the same as when the test was
started and sure enough the balloon was back to its inflated state.  Later
in the day when the temp was +10 to 15 F over when I started the test the
balloon burst.  At this point I was!
  satisfied that my tanks were leak free (hopefully they will stay that way
when they undergo the dynamic stresses of flight.)

Whether you use a balloon, manometer, altimeter, etc.  remember the pressure
will change with change in temperature under a constant volume (Ideal Gas
Law), so don't jump to the conclusion of a leak if your pressure drops when
the temperature drops.  I will recheck my tanks before I add fuel, but this
time I will pot a thermocouple into the tank to monitor the gas temperature
and the tank pressure sensor (I built a sensor array to monitor tank
pressure in flight so if I were to have a vent problem in flight, I will
know before the fuel pumps start to starve.)

Joe



  ----- Original Message ----- 
  From: Milehitaz at aol.com 
  To: reflector at tvbf.org 
  Sent: Friday, April 06, 2007 2:04 AM
  Subject: Re: REFLECTOR: Leak testing Fuel Strake


    
  Forgive me wise collective:

  I know I have read several of the posts before, never paid enough
attention to the answers as it always seemed like it would be so long before
I needed the info...

  Other than refrigerant and a "sniffer" to test the "seal" on my
strakes...Does someone have a good method they can share? My thought was low
air pressure, 2 to 3 psi  and a water bottle with a little soap in it
....spray around the outside of the strake... see if I can blow some
bubbles...Thanks in advance for your input,
  Larry Lambert XL/RG






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Message: 3
Date: Fri, 6 Apr 2007 14:35:48 EDT
From: Milehitaz at aol.com
Subject: REFLECTOR: Fuel Leak
To: reflector at tvbf.org
Message-ID: <c1d.145866a8.3347ed04 at aol.com>
Content-Type: text/plain; charset="us-ascii"

Thank you all!
 
As expected there were several excellent ideas posted... I just have to  
figure out what works best for me. Thank you so much for the heads up on
the 
PSIG...i never would have thought that 2 - 3 psi would do damage, but it
does 
make sense. Again, thanks, all the best,
 
Larry Lambert
XL/RG
 



************************************** See what's free at
http://www.aol.com.
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Message: 4
Date: Fri, 6 Apr 2007 15:35:05 EDT
From: PUSHERPILOT at wmconnect.com
Subject: Re: REFLECTOR: Fuel Leak
To: reflector at tvbf.org
Message-ID: <c14.14a039a1.3347fae9 at wmconnect.com>
Content-Type: text/plain; charset="us-ascii"

For an accurate test replace the fuel filler cap with a "plumbers plug" 
available at Home Depot.

Mel Bina Flying STD RG    </HTML>
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Message: 5
Date: Fri, 6 Apr 2007 14:45:22 -0500
From: "Darrell & Nora Kufalk" <kufalk at wi.rr.com>
Subject: Re: REFLECTOR: Fuel Leak
To: "'Velocity Aircraft Owners and Builders list'"
	<reflector at tvbf.org>
Message-ID: <005c01c77884$1d72d6b0$bce7a718 at DarrellK>
Content-Type: text/plain; charset="us-ascii"

With a very rough estimate, the fuel tank has an inside surface of over 1000
square inches on the top and another 1000 on the bottom.  Put 2 psi inside
your tank and you are putting 1 ton of force inside, pushing up and down,
trying to split it in half.

 

Darrell Kufalk

XLRG

 

 

 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Milehitaz at aol.com
Sent: Friday, April 06, 2007 1:36 PM
To: reflector at tvbf.org
Subject: REFLECTOR: Fuel Leak

 

  

Thank you all!

 

As expected there were several excellent ideas posted... I just have to
figure out what works best for me. Thank you so much for the heads up on the
PSIG...i never would have thought that 2 - 3 psi would do damage, but it
does make sense. Again, thanks, all the best,

 

Larry Lambert

XL/RG

 





  _____  

See what's free at AOL.com <http://www.aol.com?ncid=AOLAOF00020000000503> . 

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Message: 6
Date: Fri, 6 Apr 2007 15:31:23 -0600
From: "Christopher Barber" <CBarber at TexasAttorney.net>
Subject: Re: REFLECTOR: South Houston
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Message-ID: <OOECJAJLPPEPJMHNKCBHEEANGGAA.CBarber at TexasAttorney.net>
Content-Type: text/plain; charset="iso-8859-1"

Steve,

I assume that by south Houston, you do not mean the actual town of "South
Houston" (it is no longer a very good part of town).  However, if you are
meaning the southern half of the Great City of Houston, I AM YOUR MAN.  I
live (and have grown up and have had my law practice) in SE Houston, and I
work as a cop in a city called Bellaire, which is surrounded on all four
sides by SW Houston.

The second and third largest airports in Houston are on the SE side (Hobby -
HOU & Ellington-EFD...where I have a hangar).  The largest, "The big Bush"
Intercontinental Airport-IAH is about 30 miles to the north.  No real hangar
availability at HOU or IAH.  I had to wait on the EFD waiting list for a few
years.  These are the three big airports run by the City of Houston.  IAH
and HOU are mostly for airlines.  EFD is GA with the Air Guard.  It is a
former Air Force based and used extensively by NASA....i.e. "vomit comet"
the "flying guppy", T-38 with astronauts at the stick, et. al.

Smaller airports around are Pearland Regional (aka Clover Field), Houston
Southwest and Sugar Land....kinda depends with part of southern Houston you
are referring to.  Sugar Land is a good 40 minute drive from Ellington...but
still pretty much considered Houston.

Hangar space will probably run you about $350.00 per month wherever you are.
I share my hangar with a buddy who is restoring an ol' V-EZ.  It is a very
nice hangar though.

Should you have any questions, comments or concerns, please, do not hesitate
to contact me on my cell at 832-818-CELL (2355).  I am the president of EAA
Houston; Chapter 12 and hope you will consider checking us out as well.  I
hope I can help.

You will know you have made it to Houston when you realize you can DRINK
your air <g>

All the best,

Chris

Christopher Barber
Attorney and Counselor at Law
5110 Bissonnet, No 418
Bellaire, Texas 77401

Serving the Needs of Senior Texans

281-464-LAWS (5297)
281-754-4168 Fax
www.TexasAttorney.net

  -----Original Message-----
  From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of Steve Davey
  Sent: Friday, April 06, 2007 7:46 AM
  To: Velocity Aircraft Owners and Builders list
  Subject: REFLECTOR: South Houston


    I'm looking for some advice on South Houston.  I recently accepted a new
career opportunity and am now beginning the search for a new FBO/Hanger etc.
Any recommendations or thoughts will be appreciated.

    Off line address:  sadsxlrg5 at yahoo.com

    Thanks
    Steve


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