X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 24 Jun 2009 16:38:44 -0400 Message-ID: X-Original-Return-Path: Received: from betsy.gendns5.com ([65.254.38.234] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTPS id 3730746 for lml@lancaironline.net; Wed, 24 Jun 2009 08:59:50 -0400 Received-SPF: none receiver=logan.com; client-ip=65.254.38.234; envelope-from=paul@tbm700.com Received: from s01060018f83ecf6d.cg.shawcable.net ([70.72.197.235]:60255 helo=[192.168.3.101]) by betsy.gendns5.com with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.69) (envelope-from ) id 1MJS47-0003JJ-6R for lml@lancaironline.net; Wed, 24 Jun 2009 08:59:12 -0400 X-Original-Message-Id: <47C9E1B2-CA5C-483F-86D6-5ADEFE8C58AB@tbm700.com> From: paul miller X-Original-To: "Lancair Mailing List" In-Reply-To: Content-Type: multipart/alternative; boundary=Apple-Mail-10--894321752 Mime-Version: 1.0 (Apple Message framework v935.3) Subject: Re: [LML] Re: Boost pump question X-Original-Date: Wed, 24 Jun 2009 08:58:54 -0400 References: X-Mailer: Apple Mail (2.935.3) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - betsy.gendns5.com X-AntiAbuse: Original Domain - lancaironline.net X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - tbm700.com --Apple-Mail-10--894321752 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed; delsp=yes Content-Transfer-Encoding: quoted-printable Understood Jeff. I think we're a bit off-topic now since my original =20= reply referred to automatically switching to HIGH for fuel pumps. =20 Now, we've got a mix of switch wiring, turbo and non-turbo engines =20 with much different maximum fuel flows and the confusing issue of what =20= happens with HIGH setting when the EDFP is still working. I still =20 think personally that manual HIGH is a better alternative than a =20 switch and sensor that can turn on the HIGH boost without =20 annunciation. In my TBM there is an annunciator for electric boost =20 which kicks on if the fuel pressure drops. In my Legacy the builder =20 put in a 10,000 foot annunciator for the low boost pump reminder which =20= I think is a good idea. As I recall, Josh said during training, to =20 use LOW for switching tanks, above 10,000 and I think for Landing and =20= takeoff (IO550). In my setup LOW does bump up the cruise fuel flow by =20= a gallon or more. All of this simply says we need to understand fuel =20= systems very well and to use the guidance and direction of the =20 manufacturers and experience of prior builders. Paul Miller Calgary On 24-Jun-09, at 7:44 AM, vtailjeff@aol.com wrote: > Paul, > > I have worked a number of accidents allegedly caused by too much =20 > fuel flooding the engine and I have to wonder what the fuel flow =20 > guage and mixture knob are for. > > Jeff > > -----Original Message----- > From: paul miller > To: lml@lancaironline.net > Sent: Sun, Jun 21, 2009 7:29 pm > Subject: [LML] Re: Boost pump question > > You may be right but Cessna does believe it to be a risk, if not =20 > proven already. The AFM supplement incorporating MEB 88-3 included =20= > the following cautionary note: > "If the auxiliary fuel pump switches are placed in the HIGH position =20= > with the engine-driven fuel pump(s) operating normally, total loss =20 > of engine power may occur." > > > On 19-Jun-09, at 12:21 PM, vtailjeff@aol.com wrote: > >> I do not believe this to be true-- I have selected HIGH at >> But, if HIGH was selected with the mechanical, it could produce =20 >> very high flows and kill the engine so the MEB advised leaning to =20 >> prevent such an occurrence >> >> >> >> -----Original Message----- >> From: paul miller >> To: lml@lancaironline.net >> Sent: Thu, Jun 18 , 2009 8:28 pm >> Subject: [LML] Re: Boost pump question >> >> That's a really interesting design philosophy being used by Cessna =20= >> now. In the Multiengine Cessnas (I put 3000+ hours in my C414A) =20 >> the same setup was originally installed and it killed a few =20 >> people. Mandatory SB 88-3 required a change to LOW-OFF-HIGH switch =20= >> by requiring the pilot to manually select HIGH and it was =20 >> interlocked on the high side like the Columbia. It turns out =20 >> that the sensing switches and wiring were less reliable than the =20 >> engine or mechanical fuel pumps they were supposed to protect. =20 >> Glitches and failures in the sensing system triggered HIGH setting =20= >> which combined with mechanical fuel pump pressure would kill an =20 >> engine in the multis. The bottom line was that manual selection of =20= >> the high setting was deemed best practice by Cessna in 1988 in =20 >> multiengine pistons. In addition, HIGH would not sustain full =20 >> power alone so MP had to be managed to meet fuel flow. But, if =20 >> HIGH was selected with the mechanical, it could produce very high =20 >> flows and kill the engine so the MEB advised leaning to prevent =20 >> such an occurrence. >> >> Perhaps the sensing is now better or perhaps there has not been a =20 >> repeat of the problems that led to changing out that design but the =20= >> whole issue of auto HIGH fuel pump can really throw you for a loop =20= >> if it comes into play at the wrong time and you haven't selected it =20= >> manually. It's worth thinkin g about how you would deal with an =20 >> Auto HIGH kicking in properly or improperly. >> >> Paul Miller >> N357V Legacy >> N700CS TBM700A >> >> Richard T. Schaefer wrote: >>> >>> 0A >>> Dan, >>> My understanding (from reading the Columbia 400 manual) is that =20= >>> the Low mode is used for vapor suppression above 10,000 ft. >>> The High is used when the mechanical pump fails, during prime, =20 >>> and prior to a hot start to cool any heat soaked components in the =20= >>> fuel system (as the hot excess fuel is returned to your fuel tank). >>> >>> When you setup your fuel system for your engine you should =20 >>> verify that high fuel pump mode will not flood your engine. >>> >>> In the Columbia (as I understand) the prime button engages the =20 >>> high fuel mode. >>> 0D >>> They have a three way switch, LOW, OFF, and HIGH arm. >>> The HIGH arm uses a fuel pressure switch and locking relay. The =20= >>> intent is if the fuel pressure drops while on HIGH arm, the HIGH =20 >>> mode of the fuel pump is engaged and is locked in, even as the =20 >>> fuel pressure rises as a result of the pump coming on. >>> The HIGH arm is used during climb and cruise below 10,000 ft =20 >>> and set to OFF during descent. (And of course the LOW is used =20 >>> always above 10,000 ft). >>> I assume you would go to HIGH arm on a go-around =85 one more =20 >>> thing to the checklist during a busy time. >>> >>> It=92s important to make sure that HIGH and LOW are not engaged =20= >>> at the same time. So there is some=3D2 0care to how the primer =20 >>> button interacts with the three way switch. >>> >>> This is how I am setting up my IV-P. >>> >>> r.t.s. >>> >>> From: Lancair Mailing List [m ailto:lml@lancaironline.net] On =20 >>> Behalf Of Dan Reagan >>> Sent: Thursday, June 18, 2009 8:09 AM >>> To: < A class=3Dmoz-txt-link-abbreviated = href=3D"mailto:lml@lancaironline.net=20 >>> ">lml@lancaironline.net >>> Subject: [LML] Boost pump question >>> >>> Since my crankshaft bolt problem is causing me to change out my =20 >>> engine, I have decided to change from my current FADEC engine to a =20= >>> conventional mixture control engine. The boost pump I currently =20 >>> have is a 2 speed Dukes and in the past was turned on and off by =20 >>> FADEC. (It could be manually turned on as when above 10,000 feet) >>> >>> My question is, when I am rewiring the fuel pump, do I need both =20 >>> the high and the low speeds? My dumb question of the day is, when =20= >>> is the fuel pump supposed to be used on the TSIO550 in the Lancair =20= >>> IVP? >>> >>> Dan Reagan >>> IVP 650 hours >> >> >> Make your summer sizzle with fast and easy recipes for the grill. > > =3D > > Save energy, paper and money -- get the Green Toolbar. --Apple-Mail-10--894321752 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Understood Jeff.   I think = we're a bit off-topic now since my original reply referred to = automatically switching to HIGH for fuel pumps.  Now, we've got a = mix of switch wiring, turbo and non-turbo engines with much different = maximum fuel flows and the confusing issue of what happens with HIGH = setting when the EDFP is still working.  I still think personally = that manual HIGH is a better alternative than a switch and sensor that = can turn on the HIGH boost without annunciation.  In my TBM there = is an annunciator for electric boost which kicks on if the fuel pressure = drops.  In my Legacy the builder put in a 10,000 foot annunciator = for the low boost pump reminder which I think is a good idea.  As I = recall, Josh said during training, to use LOW for switching tanks, above = 10,000 and I think for Landing and = takeoff (IO550).  In my setup LOW does&= nbsp;bump up the cruise fuel flow by a&= nbsp;gallon or more.  All of this simpl= y says we need to understand fuel syste= ms very well and to use the guidance&nb= sp;and direction of the manufacturers and ex= perience of prior builders.

Paul = Miller
Calgary 

On 24-Jun-09, at = 7:44 AM, vtailjeff@aol.com = wrote:

Paul,

I have worked a number of accidents = allegedly caused by too much fuel flooding the engine and I have to = wonder what the fuel flow guage and mixture knob are for.

= Jeff

-----Original Message-----
From: paul miller <paul@tbm700.com>
To: lml@lancaironline.net
= Sent: Sun, Jun 21, 2009 7:29 pm
Subject: [LML] Re: Boost pump = question

You may be = right but Cessna does believe it to be a risk, if not proven already. =  The AFM supplement incorporating MEB 88-3 included the = following cautionary note: 
"If the auxiliary fuel pump = switches are placed in the HIGH position with the engine-driven = fuel pump(s) operating normally, total loss of engine power may = occur."


On 19-Jun-09, = at 12:21 PM, vtailjeff@aol.com = wrote:

I do not believe this to be true-- I have selected = HIGH at
But, if HIGH was selected with the mechanical, it could = produce very high flows and kill the engine so the MEB advised leaning = to prevent such an occurrence



-----Original = Message-----
From: paul miller <paul@tbm700.com>
To: lml@lancaironline.net
= Sent: Thu, Jun 18 , 2009 8:28 pm
Subject: [LML] Re: Boost pump = question

That's a really = interesting design philosophy being used by Cessna now.   In = the Multiengine Cessnas (I put 3000+ hours in my C414A) the same setup = was originally installed and it killed a few people.  Mandatory SB = 88-3 required a change to LOW-OFF-HIGH switch by requiring the pilot to = manually select HIGH and it was interlocked on the high side like the = Columbia.    It turns out that the sensing switches and = wiring were less reliable than the engine or mechanical fuel pumps they = were supposed to protect. Glitches and failures in the sensing system = triggered HIGH setting which combined with mechanical fuel pump pressure = would kill an engine in the multis.  The bottom line was that = manual selection of the high setting was deemed best practice by Cessna = in 1988 in multiengine pistons.   In addition, HIGH would not = sustain full power alone so MP had to be managed to meet fuel = flow.  But, if HIGH was selected with the mechanical, it could = produce very high flows and kill the engine so the MEB advised leaning = to prevent such an occurrence.

Perhaps the sensing is now = better or perhaps there has not been a repeat of the problems that led = to changing out that design but the whole issue of auto HIGH fuel pump = can really throw you for a loop if it comes into play at the wrong time = and you haven't selected it manually.  It's worth thinkin g about = how you would deal with an Auto HIGH kicking in properly or = improperly.

Paul Miller
N357V Legacy
N700CS TBM700A
=
Richard T. Schaefer wrote:
0A
Dan,
  My = understanding (from reading the Columbia 400 manual) is that the Low = mode is used for vapor suppression above 10,000 ft.
=
  The High is used when the mechanical pump fails, during = prime, and prior to a hot start to cool any heat soaked components in = the fuel system (as the hot excess fuel is returned to your fuel = tank).
 
  When you setup your fuel system for your engine you should = verify that high fuel pump mode will not flood your = engine.
 
  In the Columbia (as I understand) the prime button engages = the high fuel mode.
0D
  They = have a three way switch, LOW, OFF, and HIGH arm.
=
  The HIGH arm uses a fuel pressure switch and locking = relay. The intent is if the fuel pressure drops while on HIGH arm, the = HIGH mode of the fuel pump is engaged and is locked in, even as the fuel = pressure rises as a result of the pump coming on.
=
   The HIGH arm is used during climb and = cruise below 10,000 ft and set to OFF during descent. (And of course the = LOW is used always above 10,000 ft).
   I assume you would go to HIGH arm on a go-around =85 = one more thing to the checklist during a busy time.
=
 
   = It=92s important to make sure that HIGH and LOW are not engaged at the = same time. So there is some=3D2 0care to how the primer button interacts = with the three way switch.
 
  This = is how I am setting up my IV-P.
 
r.t.s.
 
From: Lancair = Mailing List [m = ailto:lml@lancaironline.net] On Behalf Of Dan Reagan
= Sent: Thursday, June 18, 2009 = 8:09 AM
To: < A = class=3Dmoz-txt-link-abbreviated href=3D"mailto:lml@lancaironline.net">= ;lml@lancaironline.net
= Subject: [LML] Boost pump = question
 
Since my crankshaft bolt = problem is causing me to change out my engine, I have decided to change = from my current FADEC engine to a conventional mixture control = engine.  The boost pump I currently have is a 2 speed Dukes and in = the past was turned on and off by FADEC. (It could be manually turned on = as when above 10,000 feet) 
 
=
My = question is, when I am rewiring the fuel pump, do I need both the high = and the low speeds?  My dumb question of the day is, when is = the fuel pump supposed to be used on the TSIO550 in the Lancair = IVP?
 
Dan = Reagan
IVP 650 hours
=

Make your = summer sizzle with fast and easy recipes for the grill.
=

=3D

Save energy, paper and money -- get the Green = Toolbar. =

= --Apple-Mail-10--894321752--