X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Sender: To: lml Date: Tue, 06 Feb 2007 08:22:19 -0500 Message-ID: X-Original-Return-Path: Received: from rwcrmhc11.comcast.net ([204.127.192.81] verified) by logan.com (CommuniGate Pro SMTP 5.1.5) with ESMTP id 1814395 for lml@lancaironline.net; Tue, 06 Feb 2007 02:11:38 -0500 Received-SPF: none receiver=logan.com; client-ip=204.127.192.81; envelope-from=j.hafen@comcast.net Received: from hafenj1 (failure[160.7.241.187]) by comcast.net (rwcrmhc11) with SMTP id <20070206071049m11008jpebe>; Tue, 6 Feb 2007 07:10:49 +0000 From: "John Hafen" X-Original-To: "Lancair Mail List " Subject: Summary - when to turn on the fuel boost pump X-Original-Date: Tue, 6 Feb 2007 00:10:43 -0700 X-Original-Message-ID: <000701c749bd$ee76fb10$bbf107a0@engagethoughtware.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0008_01C74983.4219A9B0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_0008_01C74983.4219A9B0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I would like to thank all those who responded to my question about when = to turn on the fuel boost pump when flying a Lancair IVP. =20 Based on info gleaned from the posts, it appears that the answer is "whenever it is necessary depending on your specific plane." As some = never use their boost pump after engine start, others turn it on for take off, others turn it on at 3k feet or 6k feet or 10k feet or after reaching = cruise at 24k feet, it appears that there is no dependably consistent answer = that would apply to every plane, even in identical environments (temperature, pressure etc). We are left to figure it out on our own. But at least I know a little bit about why, thanks to your feedback. =20 =20 It appears that the "right" answer is all over the board because of at = least the following reasons (there may be more): =20 * Fuel flow set-up varies from plane to plane =20 * The internal leakage of the metering pump varies considerably from unit to unit =20 * Vaporization level and rate of the fuel, because of heat and thus cavitation in the engine driven pump, especially if that pump is also = heat saturated from the engine operation, varies from plane to plane=20 =20 * Fuel flow varies from plane to plane because of varying mounting locations of the fuel boost pump=20 =20 Not everyone is happy with these seemingly random and unpredictable (especially on your first flight) variations. Bob Mackey typifies the sentiment of many with: =20 It seems that the job of fuel flow regulation is relegated to the pilot. = The pilot has access to two pump switches, a mixture knob, and a fuel cutoff valve. With those tools he attempts to keep the fuel flow to the = cylinders within a narrow range of acceptable mixtures. If he fails, the engine = quits now, or overheats, detonates, and may quit later.=20 =20 It appears to me that the safety of these pilots and their passengers = could be=20 improved more by fixing the flaws in the fuel supply and injection = system than by learning better switchology.=20 =20 The posts that came in were mostly helpful and very informative. Some = were not. I've listed brief excerpts of some "Helpful Comments" below. (I deleted my original "Less then Helpful Comments" section in an attempt = to not embarrass anyone to the point that they would be tempted to hunt me = down and kill me. There are enough of those people out there already.) =20 Helpful Comments: =20 Everything from Gary Casey, especially: "If the flow is predictable, = then why is there so much effort required to "set up" the system for each = engine? I'm not sure, but the internal leakage of the metering pump surely = varies considerably from unit to unit." =20 Mike Easley's Continental Fuel Injection Setup PDF. =20 =20 Scott Krueger: "On the other hand, a fuel injected engine, say a Lyc = 320 with an RSA style fuel system, generally requires that some level of = fuel pressure must be maintained so the stinking throttle body can match it = to the air via pressure measured by some weenie tubes in the induction = stream so that ultimately it can deliver the correct fuel flow to the = injectors. The ideal pressure is about 26 psi, but the system only gets upset if = the pressure drops below 12 psi (fluctuations between those values don't = seem to make much difference). How can such variation happen? Well, one way is vaporization of the fuel because of heat and thus cavitation in the = engine driven pump, especially if that pump is also heat saturated from the = engine operation." =20 And: "If you haven't already considered a test pilot for the first = flight, you should do so. If you haven't at least been to an HPAT ground = school, you should go before you fly. You should be current and flying = something that is high performance and complex now. You should also be in contact with your aviation insurance company as they may have some "suggestions" about your training in order for you to obtain hull coverage." =20 Colyn Case: "If you haven't taken the APS course I HIGHLY recommend it. = I went in thinking I would learn the fine points of LOP operation and came = out realizing how very easy it is to destroy your engine doing pretty much = what we've all been taught to do. This is all backed up by hard data. = ...and now you can take it on line cheap. Check out = http://www.advancedpilot.com/ for only $395." =20 Bill Maddox: "I see only one way this accident problem can be = reduced.that is to set up a program with either of these schools as a pre-requirement = to flying this equipment. I said this some time past on this site and = nothing has changed other than the accidents keep developing at a faster rate = than it should be. I think training in the sims is a must and invaluable. Sitting at a desk and hearing about a situation is one thing, but really being in one in a sim is where the real training occurs." =20 Bob Mackey: "A reliable system is one that stays within its proper operating range even when its inputs are out of spec. It appears from the published = accounts on this forum that the fuel flow varies with fuel supply pressure..It appears to me that the safety of these pilots and their passengers could = be improved more by fixing the flaws in the fuel supply and injection = system than by learning better switchology." =20 To Safe and Happy Flying John Hafen N413AJ To be flying in the Spring (not sure which year) =20 ------=_NextPart_000_0008_01C74983.4219A9B0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

I would like to thank all those who responded to my question = about when to turn on the fuel boost pump when flying a Lancair = IVP.

 

Based on info gleaned from the posts, it appears that the answer = is “whenever it is necessary depending on your specific = plane.”  As some never use their boost pump after engine start, others turn it on = for take off, others turn it on at 3k feet or 6k feet or 10k feet or after = reaching cruise at 24k feet, it appears that there is no dependably consistent = answer that would apply to every plane, even in identical environments = (temperature, pressure etc).  We are left to figure it out on our own.  But = at least I know a little bit about why, thanks to your feedback.  =

 

It appears that the “right” answer is all over the = board because of at least the following reasons (there may be = more):

 

  • Fuel flow set-up varies from plane to = plane

 

  • The internal leakage of the metering = pump varies considerably from unit to unit

 

  • Vaporization level and rate of the fuel, because of heat and thus cavitation in = the engine driven pump, especially if that pump is also heat = saturated from the engine operation, varies from plane to plane =

 

  • Fuel flow = varies from plane to plane because of varying mounting locations of the fuel = boost pump

 

Not everyone is happy with these = seemingly random and unpredictable (especially on your first flight) = variations.  Bob Mackey typifies the sentiment of many with:

 

It seems that the job of fuel flow regulation = is relegated to the pilot. The pilot has access to two pump switches, a = mixture knob, and a fuel cutoff valve. With those tools he attempts to keep the = fuel flow to the cylinders within a narrow range of acceptable mixtures. If = he fails, the engine quits now, or overheats, detonates, and may quit = later.

 

It appears to me that the safety of these = pilots and their passengers could be

improved more by fixing the flaws in the fuel = supply and injection system than by learning better switchology. =

 

The posts that came in were mostly helpful and very = informative.  Some were not.  I’ve listed brief excerpts of some = “Helpful Comments” below.  (I deleted my original “Less then Helpful = Comments” section in an attempt to not embarrass anyone to the point that they = would be tempted to hunt me down and kill me.  There are enough of those = people out there already.)

 

Helpful Comments:

 

Everything from Gary Casey, especially:  “If the flow = is predictable, then why is there so much effort required to "set = up" the system for each engine?  I'm not sure, but the internal leakage = of the metering pump surely varies considerably from unit to = unit.”

 

Mike Easley’s Continental Fuel Injection Setup PDF.  =

 

Scott Krueger:  “On = the other hand, a fuel injected engine, say a Lyc 320 with an RSA style fuel = system, generally requires that some level of fuel pressure must be maintained = so the stinking throttle body can match it to the air via pressure = measured by some weenie tubes in the induction stream so = that ultimately it can deliver the correct fuel flow to the injectors.  The ideal = pressure is about 26 psi, but the system only gets upset if the pressure drops below = 12 psi (fluctuations between those values don't seem to make much = difference).  How can such variation happen?  Well, one way is = vaporization of the fuel because of heat and thus cavitation in the engine driven = pump, especially if that pump is also heat saturated from the engine = operation.”

 

And:  “If you haven't = already considered a test pilot for the first flight, you should do so.  If = you haven't at least been to an HPAT ground school, you should go before you fly.  You should be current and flying something that is high = performance and complex now.  You should also be in contact with your = aviation insurance company as they may have some "suggestions" about = your training in order for you to obtain hull = coverage.”

 

Colyn = Case:  “If you haven't taken the APS course I HIGHLY recommend it. I went = in thinking I would learn the fine points of LOP operation and came out = realizing how very easy it is to destroy your engine doing pretty much what we've = all been taught to do. This is all backed up by hard data.   = ...and now you can take it on line cheap.  Check out http://www.advancedpilot.com/ = for only $395.”

 

Bill = Maddox:  “I see only one way this accident problem can be = reduced…that is to set up a program with either of these schools as a pre-requirement to = flying this equipment. I said this some time past on this site and nothing has = changed other than the accidents keep developing at a faster rate than it should = be.  I think training in the sims is a must and invaluable. Sitting at a desk = and hearing about a situation is one thing, but really being in one in a sim = is where the real training occurs.”

 

Bob Mackey:  “A reliable system is one that stays = within its proper operating range

even when its inputs are out of spec. It appears from the = published accounts on this forum that the fuel flow varies with fuel supply pressure….It appears to me that the safety of these pilots and = their passengers could be improved more by fixing the flaws in the fuel supply = and injection system than by learning better = switchology.”

 

To Safe and Happy Flying

John Hafen

N413AJ

To be flying in the Spring (not sure which = year)

 

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