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Return-Path: <13brv3@bellsouth.net> Received: from imf21aec.mail.bellsouth.net ([205.152.59.69] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 548181 for flyrotary@lancaironline.net; Sun, 28 Nov 2004 10:51:53 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.69; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf21aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20041128155124.SBGY2054.imf21aec.mail.bellsouth.net@rd> for ; Sun, 28 Nov 2004 10:51:24 -0500 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Bubbles in fuel line from pump - new valve Date: Sun, 28 Nov 2004 09:51:45 -0600 Message-ID: <000001c4d562$29ce6540$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C4D52F.DF33F540" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C4D52F.DF33F540 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Had a disappointing test flight yesterday. Removed the fuel flow sensor. Replaced it with clear line. That vertical clear line started getting air (vapor?) in it, even after reducing power and pointing nose downwards. Something else is going on here I haven't nailed down. Will put back the fuel tank vent and try again. =20 =20 Sorry to hear you're still having troubles with this. You mentioned = wanting to check the fuel pickup, but never said anything about doing that. = Since this is a fuselage tank, I'm guessing that the pickup is short, and is = all located near the bottom of the tank? Is the whole pickup remaining submerged in flight? If so, that would rule out a leak on the pickup = line, internal to the tank. =20 =20 Does the problem get better with a full tank of fuel, as opposed to a partial tank? As many times as you've had to drain it, I'm guessing you aren't really topping it off for most of these tests. =20 =20 If it were me, I'd try to get the lines as full as possible on the = ground, then pull just a tiny bit of suction on the fuel tank vent. It = shouldn't take much, and you certainly don't want to damage the tank. If there's = an air leak, it should show up as more bubbles getting into the line, and = maybe you can see where they're coming from.=20 =20 Another thought- on my original Kolb Slingshot, I had a clear filter = that was oriented vertically. Fuel came from the tank below, into the bottom fitting of the filter, then out the top of the filter to the engine = above. That damn filter stayed half full of air ALL the time. I could manually fill it, but after just a few minutes of running, it would be half full = of air again. I wasn't using clear fuel lines, but if I had been, I'm = sure I would have seen bubbles. I can't tell you how many hours I spent trying = to fix that "problem", but I can tell you that it never changed. I can = also tell you that the engine never missed a beat because of it. Others saw = the same thing, and no one could explain it. Apparently, that's just how it = is. =20 For a moment, let's assume that all your work on the fuel lines has = proven that there's really no leak, or problems. How about the carbs? Is = there a chance you have a needle/seat that's sticking partly open. Is there a chance that the fuel level in the bowls is getting off level enough that it's causing problems? Just looking for another possibility. =20 Good luck, Rusty =20 ------=_NextPart_000_0001_01C4D52F.DF33F540 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

Had a disappointing test flight yesterday. Removed the fuel flow = sensor.=20 Replaced it with clear line.
That vertical clear line started getting = air=20 (vapor?) in it, even after reducing power and pointing nose=20 downwards.
Something else is going on here I haven't nailed down. = Will put=20 back the fuel tank vent and try again.

Sorry=20 to hear you're still having troubles with this. You = mentioned=20 wanting to check the fuel pickup, but never said anything about = doing=20 that. Since this is a fuselage tank, I'm guessing that = the=20 pickup is short, and is all located near the bottom of the = tank? Is=20 the whole pickup remaining submerged in flight? If so, that would = rule out=20 a leak on the pickup line, internal to the = tank.

Does the=20 problem get better with a full tank of fuel, as opposed to a = partial=20 tank? As many times as you've had to drain it, I'm guessing=20 you aren't really topping it off for most of these=20 tests.

If it were=20 me, I'd try to get the lines as full as possible on the ground, then = pull just a=20 tiny bit of suction on the fuel tank vent. It shouldn't take much, = and you=20 certainly don't want to damage the tank. If there's an air leak, = it should=20 show up as more bubbles getting into the line, and maybe you can see = where=20 they're coming from.

Another=20 thought- on my original Kolb Slingshot, I had a clear filter that was = oriented=20 vertically. Fuel came from the tank below, into the bottom fitting = of the=20 filter, then out the top of the filter to the engine above. That = damn=20 filter stayed half full of air ALL the time. I could manually fill = it, but=20 after just a few minutes of running, it would be half full of air=20 again. I wasn't using clear fuel lines, but if I had = been, I'm=20 sure I would have seen bubbles. I can't tell you how many hours I = spent=20 trying to fix that "problem", but I can tell you that it never = changed. I=20 can also tell you that the engine never missed a beat because of=20 it. Others saw the same thing, and no one could explain = it. =20 Apparently, that's just how it is.

For a moment,=20 let's assume that all your work on the fuel lines has proven that = there's really=20 no leak, or problems. How about the carbs? Is there a chance = you=20 have a needle/seat that's sticking partly open. Is there a chance = that the=20 fuel level in the bowls is getting off level enough that it's causing=20 problems? Just looking for another = possibility.

Good=20 luck,

Rusty

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