X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 18 May 2011 08:42:33 -0400 Message-ID: X-Original-Return-Path: Received: from vms173019pub.verizon.net ([206.46.173.19] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4987298 for lml@lancaironline.net; Wed, 18 May 2011 08:01:39 -0400 Received-SPF: pass receiver=logan.com; client-ip=206.46.173.19; envelope-from=n5zq@verizon.net Received: from p6520y ([unknown] [173.72.167.62]) by vms173019.mailsrvcs.net (Sun Java(tm) System Messaging Server 7u2-7.02 32bit (built Apr 16 2009)) with ESMTPA id <0LLE00D5X41LAKC0@vms173019.mailsrvcs.net> for lml@lancaironline.net; Wed, 18 May 2011 07:00:59 -0500 (CDT) X-Original-Message-id: From: "Bill Harrelson" X-Original-To: "Lancair Mailing List" X-Original-Cc: References: In-reply-to: Subject: Re: [LML] Fuel restriction or air? X-Original-Date: Wed, 18 May 2011 08:00:58 -0400 MIME-version: 1.0 Content-type: multipart/alternative; boundary="----=_NextPart_000_0196_01CC1531.B88E8330" X-Priority: 3 X-MSMail-priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3508.1109 X-MIMEOLE: Produced By Microsoft MimeOLE V15.4.3508.1109 This is a multi-part message in MIME format. ------=_NextPart_000_0196_01CC1531.B88E8330 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Good point, Bill. The check valves supplied by Lancair for the vent = system on my IV are free flowing inward and =E2=80=9Csomewhat=E2=80=9D = restricted flowing outward. This prevents venting a lot of fuel = overboard while taxiing with full wing tanks (no winglets) yet allows = air to escape at a relatively slow rate to avoid the problem that you = describe. Certainly, a normal one way valve (free flow one direction = =E2=80=93 no flow in the other) should NOT be used on a vent system. Bill Harrelson N5ZQ 320 1,900 hrs N6ZQ IV under construction From: Bill Hannahan=20 Sent: Wednesday, May 18, 2011 7:43 AM To: lml@lancaironline.net=20 Subject: [LML] Fuel restriction or air? =20 {Did you verify the fuel vents are working properly? ....and = that the check valves on the vents are oriented correctly?} =20 There should be no check valves on vent lines. If you take off at = sea level with a wing tank at atmospheric pressure, 14.7 psia trapped by = a check valve, and climb to 18,000 feet, static pressure 7.35 psia, the = differential pressure on the tank will be 7.35 psi, 1,058 pounds per = square foot trying 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 =20 ------=_NextPart_000_0196_01CC1531.B88E8330 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
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 outward. This=20 prevents venting a lot of fuel overboard while taxiing with full wing = tanks (no=20 winglets) yet allows air to escape at a relatively slow rate to avoid = the=20 problem that you describe. Certainly, a normal one way valve (free flow = one=20 direction =E2=80=93 no flow in the other) should NOT be used on a vent = system.
 
Bill Harrelson
N5ZQ 320 1,900 hrs
N6ZQ  IV under construction
 
 
 
 
Sent: Wednesday, May 18, 2011 7:43 AM
Subject: [LML] Fuel restriction or air?
 
------=_NextPart_000_0196_01CC1531.B88E8330--

 

{Did you verify the fuel vents are working=20 properly?   ....and that the check valves on the vents = are=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 psia=20 trapped by a check valve, and climb to 18,000 feet, static = pressure 7.35=20 psia, the differential pressure on the tank will be 7.35 psi, = 1,058 pounds=20 per square foot trying to rip the skins off the spar and ribs.

 

Vent lines must be free flowing both=20 directions.


 

Regards,
Bill Hannahan