X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 2 [X] Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 10 May 2007 11:16:48 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m20.mx.aol.com ([64.12.137.1] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2035995 for lml@lancaironline.net; Thu, 10 May 2007 10:47:09 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.1; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m20.mx.aol.com (mail_out_v38_r9.2.) id q.ce3.1018de47 (29678) for ; Thu, 10 May 2007 10:46:16 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Thu, 10 May 2007 10:46:16 EDT Subject: Re: [LML] Re: IO-550 fuel injection, Possible Fuel Vent Clogging Problem X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1178808376" X-Mailer: 9.0 Security Edition for Windows sub 5365 X-Spam-Flag: NO -------------------------------1178808376 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 5/10/2007 8:49:27 A.M. Central Daylight Time, MikeEasley@aol.com writes: A couple comments on the vent lines. My super fastbuild has 3/8" vent lines, but the original ESs had 1/4". I found this out AFTER building my wingtips with the 1/4" tubing per the manual. There was also an SB on the original tubing used in the vent lines. I had a IV in my hangar for some interior work that had a wing tank fuel leak. I had to drain the tank and wasn't sure I could keep up with the flow after taking out the quick drain. So I put a piece of duct tape over the NACA. The fuel practically stopped flowing after less than 1 gallon. That's with 35 gallons of head pressure. I'm thinking that a clogged vent would be impossible to overcome with the boost pump. If it was me, I think I'd do some more searching, very mysterious. Mike, Not so mysterious..... Consider a mud dauber plugging a vent whilst parked for a picnic. The failure to draw fuel is only one of the problems as you can switch tanks. If you are down to the last tank and the vacuum created by the engine/boost pump is great enough, consider the pressing structural issues on the tank walls (pun intended). You do inspect the vents before each flight, don't you? Did you also install vented gas caps for vacuum relief? If so, the cap should also contain a check valve to stop outflow while the tank is slightly pressurized by the vent that's hanging out in the airstream. Look at it this way - After sucking all that can be sucked and in the engine out descent, the pressure differential is increased and the probability of wing skin collapse may also increase. Remember that bottle of Evian you sipped thru the flight at altitude? After closing the cap, remember how it looked when you landed, all collapsed and shriveled up? Ah, the beauty of the 200/300 series. Wee Facet pumps, used to push wing fuel into the header, do not make that much head. If the crucial engine-feeding header tank vent gets plugged, pressure relief is obtained by pulling fuel (or air if the wing is empty) from either or both wings - a double backup. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) Darwinian culling phrase: Watch This! ************************************** See what's free at http://www.aol.com. -------------------------------1178808376 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 5/10/2007 8:49:27 A.M. Central Daylight Time,=20 MikeEasley@aol.com writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

A couple comments on the vent lines. My super fastbuild has 3/8= "=20 vent lines, but the original ESs had 1/4". I found this out AFTER=20 building my wingtips with the 1/4" tubing per the manual. There was=20= also=20 an SB on the original tubing used in the vent lines.

I had a IV in my hangar for some interior work that had a wing tank f= uel=20 leak. I had to drain the tank and wasn't sure I could keep up with t= he=20 flow after taking out the quick drain. So I put a piece of duct tape= =20 over the NACA. The fuel practically stopped flowing after = less=20 than 1 gallon. That's with 35 gallons of head pressure. I= 'm=20 thinking that a clogged vent would be impossible to overcome with the boos= t=20 pump.

If it was me, I think I'd do some more searching, very=20 mysterious.

Mike,

Not so mysterious..... Consider a mud dauber plugging a vent whil= st=20 parked for a picnic. The failure to draw fuel is only one of the probl= ems=20 as you can switch tanks. If you are down to the last tank and the vacu= um=20 created by the engine/boost pump is great enough, consider the pressing= =20 structural issues on the tank walls (pun intended).

You do inspect the vents before each flight, don't you? Did=20= you=20 also install vented gas caps for vacuum relief? If so, the cap sh= ould=20 also contain a check valve to stop outflow while the tank is sligh= tly=20 pressurized by the vent that's hanging out in the airstream.

Look at it this way - After sucking all that can be sucked and in the=20 engine out descent, the pressure differential is increased and the=20 probability of wing skin collapse may also increase. Remember tha= t=20 bottle of Evian you sipped thru the flight at altitude? After closing=20= the=20 cap, remember how it looked when you landed, all collapsed and shriveled=20 up?

Ah, the beauty of the 200/300 series. Wee Facet pumps, used = to=20 push wing fuel into the header, do not make that much head. =20= If=20 the crucial engine-feeding header tank vent gets plugged, pressure= =20 relief is obtained by pulling fuel (or air if the wing is empty) from either= or=20 both wings - a double backup.

Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)

Darwinian culling phrase: Watch=20 This!

See what's fr= ee at AOL.com.=

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