X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 19 May 2011 11:11:52 -0400 Message-ID: X-Original-Return-Path: Received: from imr-da03.mx.aol.com ([205.188.105.145] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4987767 for lml@lancaironline.net; Wed, 18 May 2011 15:05:09 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.145; envelope-from=MikeEasley@aol.com Received: from mtaomg-db04.r1000.mx.aol.com (mtaomg-db04.r1000.mx.aol.com [172.29.51.202]) by imr-da03.mx.aol.com (8.14.1/8.14.1) with ESMTP id p4IJ4L3G017438 for ; Wed, 18 May 2011 15:04:21 -0400 Received: from core-mkb001b.r1000.mail.aol.com (core-mkb001.r1000.mail.aol.com [172.29.98.1]) by mtaomg-db04.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id 7A055E000086 for ; Wed, 18 May 2011 15:04:21 -0400 (EDT) From: MikeEasley@aol.com X-Original-Message-ID: <67446.5671f824.3b057235@aol.com> X-Original-Date: Wed, 18 May 2011 15:04:21 -0400 (EDT) Subject: Re: [LML] Re: Fuel restriction or air? X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_67446.5671f824.3b057235_boundary" X-Mailer: AOL 9.6 sub 5001 X-AOL-IP: 75.71.55.189 X-Originating-IP: [75.71.55.189] x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:438322304:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d33ca4dd4183548ee --part1_67446.5671f824.3b057235_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en I had to drain a tank on a IV to repair a fuel leak. I plugged the vent= =20 while I removed the drain valve from the bottom of the wing, with the hope = =20 that it would slow the flow of fuel down my arm. I only got about a half = =20 gallon from the tank until the flow slowed to a drip. I don't think the = =20 engine driven pump or boost pump could overcome the vacuum caused by a clog= ged =20 vent line. So a clogged vent would stop the engine I'm guessing, not cause= =20 it to surge. =20 I did the calculation one time to determine the air flow that has to come = =20 in the vents to replace the fuel going into the engine. I have 3/8" vent = =20 lines on my ES and that air is moving through that vent line a couple feet = =20 per second if I remember correctly. =20 Mike Easley Colorado Springs =20 =20 In a message dated 5/18/2011 6:42:57 A.M. Mountain Daylight Time, =20 n5zq@verizon.net writes: =20 Good point, Bill. The check valves supplied by Lancair for the vent system= =20 on my IV are free flowing inward and =E2=80=9Csomewhat=E2=80=9D restricted = flowing =20 outward. This prevents venting a lot of fuel overboard while taxiing with f= ull =20 wing tanks (no winglets) yet allows air to escape at a relatively slow rate= to=20 avoid the problem that you describe. Certainly, a normal one way valve=20 (free flow one direction =E2=80=93 no flow in the other) should NOT be use= d on a vent =20 system. =20 Bill Harrelson N5ZQ 320 1,900 hrs N6ZQ IV under construction =20 =20 =20 =20 =20 =20 From: _Bill Hannahan_ (mailto:wfhannahan@yahoo.com) =20 Sent: Wednesday, May 18, 2011 7:43 AM To: _lml@lancaironline.net_ (mailto:lml@lancaironline.net) =20 Subject: [LML] Fuel restriction or air? =20 _ =20 {Did you verify the fuel vents are working properly? ....and that the=20 check valves on the vents are oriented correctly?}=20 There should be no check valves on vent lines. If you take off at sea=20 level with a wing tank at atmospheric pressure, 14.7 psia trapped by a che= ck=20 valve, and climb to 18,000 feet, static pressure 7.35 psia, the differenti= al=20 pressure on the tank will be 7.35 psi, 1,058 pounds per square foot trying= =20 to rip the skins off the spar and ribs.=20 Vent lines must be free flowing both directions.=20 Regards, Bill Hannahan wfhannahan@yahoo.com_ (mailto:wfhannahan@yahoo.com)=20 --part1_67446.5671f824.3b057235_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
I had to drain a tank on a IV to repair a fuel leak.  I plugged t= he=20 vent while I removed the drain valve from the bottom of the wing, with the = hope=20 that it would slow the flow of fuel down my arm.  I only got about a h= alf=20 gallon from the tank until the flow slowed to a drip.  I don't think t= he=20 engine driven pump or boost pump could overcome the vacuum caused by a clog= ged=20 vent line.  So a clogged vent would stop the engine I'm guessing, not = cause=20 it to surge.
 
I did the calculation one time to determine the air flow that has to c= ome=20 in the vents to replace the fuel going into the engine.  I have 3/8" v= ent=20 lines on my ES and that air is moving through that vent line a couple = feet=20 per second if I remember correctly.
 
Mike Easley
Colorado Springs
 
In a message dated 5/18/2011 6:42:57 A.M. Mountain Daylight Time,=20 n5zq@verizon.net writes:
=
Good point, Bill. The check valves supplied by Lancair for the vent= =20 system on my IV are free flowing inward and =E2=80=9Csomewhat=E2=80=9D re= stricted flowing=20 outward. This prevents venting a lot of fuel overboard while taxiing with= full=20 wing tanks (no winglets) yet allows air to escape at a relatively slow ra= te to=20 avoid the problem that you describe. Certainly, a normal one way valve (f= ree=20 flow one direction =E2=80=93 no flow in the other) should NOT be used on = a vent=20 system.
 
Bill Harrelson
N5ZQ 320 1,900 hrs
N6ZQ  IV under construction
 
 
 
 
From: = Bill=20 Hannahan
Sent: Wednesday, May 18, 2011 7:43 AM
Subject: [LML] Fuel restriction or air?
 

 

{Did you verify the fuel vents are working=20 properly?   ....and that the check valves on the vents ar= e=20 oriented correctly?}

 

There should be no check valves on vent lines.= If you=20 take off at sea level with a wing tank at atmospheric pressure, 14.= 7=20 psia trapped by a check valve, and climb to 18,000 feet, static pre= ssure=20 7.35 psia, the differential pressure on the tank will be 7.35 psi, = 1,058=20 pounds per square foot trying to rip the skins off the spar and=20 ribs.

 

Vent lines must be free flowing both=20 directions.


 

Regards,
Bill Hannahan

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