Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Mon, 27 Sep 2004 22:13:34 -0400 Message-ID: X-Original-Return-Path: Received: from rwcrmhc11.comcast.net ([204.127.198.35] verified) by logan.com (CommuniGate Pro SMTP 4.2.3) with ESMTP id 434793 for lml@lancaironline.net; Mon, 27 Sep 2004 21:39:33 -0400 Received-SPF: none receiver=logan.com; client-ip=204.127.198.35; envelope-from=edechazal@comcast.net Received: from cc1860069a (pcp09040864pcs.rocsth01.mi.comcast.net[69.244.182.42]) by comcast.net (rwcrmhc11) with SMTP id <2004092801390301300lnvdte>; Tue, 28 Sep 2004 01:39:03 +0000 X-Original-Message-ID: <00ce01c4a4fb$a24390a0$6401a8c0@rocsth01.mi.comcast.net> From: X-Original-To: "Lancair Mailing List" References: Subject: LNC2 Vacuum failure and Boost pump problem X-Original-Date: Mon, 27 Sep 2004 21:36:52 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00CB_01C4A4DA.1A501C20" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_00CB_01C4A4DA.1A501C20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Here are two stumpers I'd really appreciate some advice on. I'm just = wrapping up the annual and started the engine up for a test flight. 1. Vacuum failure - after startup the vacuum gage read zero and the = artificial horizon did not budge. In addition there was a new squealing = sound when the rpm was 1,000 or less. Sounded terrible, like dry = bearings. All other engine readings were normal. The AP thinks it's = the vacuum pump (Parker unit with 300 hours and 4 years on it). What's = confusing him is that the pump shaft turns with the prop, when every = case he's seen, the shaft shears and the pump internals don't turn with = the prop. There are holes in the pump case allowing you to see rotation. = Since all lines are attached (I did not disconnect anything in this = circuit for the annual), I figure it has to be the pump or the = regulator. The AP thinks that if the regulator somehow stuck open, = there would still be enough vacuum drawn to show something. Anybody = think it's not the pump? 2. Fuel Boost pump not pressurizing - My system has the normal header = tank, an inline fuel filter mounted horizontally right below the tank, = then the boost pump below the filter (all on the cabin side of the = firewall), then to the gascolator. The Dukes boost pump never worked = well from day one. Most days, it would seem like it was sucking air. = Sometimes it would pressurize. I switched this annual to another used = pump that I was assured worked well. This pump appears to be sucking = air too. To check fuel flow, I opened the drain valve on the gascolator = and got a steady flow out. That means fuel is definitely flowing past = the boost pump. Leaving the drain open, when I turn on the boost pump, = the flow out the drain valve stops. Turn the pump off and the flow = starts back up again. It's as if the pump was working backwards. I = switched the power leads and no difference. My previous pump would flow = like gangbusters out the gascolator drain when I did this. The new pump = went in exactly the same way as the old pump, but it's 20 or so serial = units newer. When looking at the fuel dump overboard port, I have fuel = going into the right side and exiting the left side. One mistake I made on the old pump installation is that I assembled the = fittings to the pump without o-rings and used thread sealant (no idea = what I must have been thinking). These fittings are straight threads = requiring o-rings. Don't know if that explained the sucking air problem = and the customary fuel smell for 30 seconds immediately after takeoff. =20 Anyway, I'm stumped. Some of you have mentioned putting your boost pump = low under the seats, but that's been guys running without header tanks. = In my case, I can't see how that would make a difference. Could the = horizontally mounted inline fuel filter (trapped air in that thing) = cause a problem? Regards, Ed de Chazal ------=_NextPart_000_00CB_01C4A4DA.1A501C20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Here are two stumpers = I'd really=20 appreciate some advice on.  I'm just wrapping up the annual and = started the=20 engine up for a test flight.
 
1.  Vacuum failure = - after=20 startup the vacuum gage read zero and the artificial horizon did not=20 budge.  In addition there was a new squealing sound when the rpm = was 1,000=20 or less.  Sounded terrible, like dry bearings.  All other = engine=20 readings were normal.  The AP thinks it's the vacuum pump (Parker = unit with=20 300 hours and 4 years on it). What's confusing him is that the pump = shaft turns=20 with the prop, when every case he's seen, the shaft shears and the pump=20 internals don't turn with the prop. There are holes in the pump case = allowing=20 you to see rotation.  Since all lines are attached (I did not = disconnect=20 anything in this circuit for the annual), I figure it has to be the pump = or the=20 regulator.  The AP thinks that if the regulator somehow stuck open, = there=20 would still be enough vacuum drawn to show something.  Anybody = think it's=20 not the pump?
 
2.  Fuel Boost = pump not=20 pressurizing - My system has the normal header tank, an inline fuel = filter=20 mounted horizontally right below the tank, then the boost pump below the = filter=20 (all on the cabin side of the firewall), then to the gascolator.  = The Dukes=20 boost pump never worked well from day one.  Most days, it would = seem like=20 it was sucking air.  Sometimes it would pressurize.  I = switched this=20 annual to another used pump that I was assured worked well.  This = pump=20 appears to be sucking air too.  To check fuel flow, I opened the = drain=20 valve on the gascolator and got a steady flow out.  That means fuel = is=20 definitely flowing past the boost pump.  Leaving the drain open, = when I=20 turn on the boost pump, the flow out the drain valve stops.  Turn = the pump=20 off and the flow starts back up again.  It's as if the pump was = working=20 backwards.  I switched the power leads and no difference. My = previous pump=20 would flow like gangbusters out the gascolator drain when I did = this.  The=20 new pump went in exactly the same way as the old pump, but it's 20 or so = serial=20 units newer.  When looking at the fuel dump overboard port, I have = fuel=20 going into the right side and exiting the left side.
 
One mistake I made on = the old pump=20 installation is that I assembled the fittings to the pump without = o-rings and=20 used thread sealant (no idea what I must have been thinking).  = These=20 fittings are straight threads requiring o-rings.  Don't know if = that=20 explained the sucking air problem and the customary fuel smell for 30 = seconds=20 immediately after takeoff. 
 
Anyway, I'm = stumped.  Some of=20 you have mentioned putting your boost pump low under the seats, but = that's been=20 guys running without header tanks.  In my case, I can't see how = that would=20 make a difference.  Could the horizontally mounted inline fuel = filter=20 (trapped air in that thing) cause a problem?
 
Regards,
Ed de=20 Chazal
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