X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-da03.mx.aol.com ([205.188.105.145] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTP id 5599451 for flyrotary@lancaironline.net; Thu, 14 Jun 2012 11:03:39 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.145; envelope-from=ARGOLDMAN@aol.com Received: from mtaomg-mb05.r1000.mx.aol.com (mtaomg-mb05.r1000.mx.aol.com [172.29.41.76]) by imr-da03.mx.aol.com (8.14.1/8.14.1) with ESMTP id q5EF2rSR003516 for ; Thu, 14 Jun 2012 11:02:54 -0400 Received: from core-dsb002c.r1000.mail.aol.com (core-dsb002.r1000.mail.aol.com [172.29.253.5]) by mtaomg-mb05.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id E13D4E000085 for ; Thu, 14 Jun 2012 11:02:53 -0400 (EDT) From: ARGOLDMAN@aol.com Message-ID: <3e3ad.2da8b56a.3d0b571d@aol.com> Date: Thu, 14 Jun 2012 11:02:53 -0400 (EDT) Subject: Re: [FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel presure qu... To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_3e3ad.2da8b56a.3d0b571d_boundary" X-Mailer: AOL 9.6 sub 168 X-Originating-IP: [24.14.64.174] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20110426; t=1339686174; bh=gAONhVlMwwR3EBUdiuzVlVevnl6HIOJCL6FBL6/DB6Y=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=iuiZ6zA29pL3IJqSU3AOExpp7waYLYo4YB3c7pwa05HVLQbiNaYaQdkLY7I9Q0maH Is5/WpXoEv2+g2B9Bqdne5EkGPteDWnTD9axal09rNVzJ79RRLCrjiLprIgkXGfBUG SDNXlqqRWvIzt8XTObtthTiIQ8ocdPi21vtnZZY4= X-AOL-SCOLL-SCORE: 0:2:481139936:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d294c4fd9fd1d01ad --part1_3e3ad.2da8b56a.3d0b571d_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en OOOOOOO, =20 A 35 A breaker--- for the pump??? =20 Since the breaker is supposed to protect the wire from heat rise and =20 eventual fire, not the pump, that kind of amperage rating is appropriate fo= r a =20 10 Ga wire for short periods of time (a 30A rating) or 8 Ga continuous (a = =20 40A rating). The rating of wire is based on heat-rise, (I think it is 25*C = in =20 bundled wire). The rating increases if the wire is well ventilated and not = =20 bundled, or is overloaded for short periods of time such as smaller gauge,= =20 than appropriate, used in a starter circuit. The heat comes from the=20 resistance of the wire to the electric flow. This resistance decreases wit= h =20 decreasing Gauge. =20 Is he/are they really running that kind of wire to their pumps or do they = =20 just uprate the breakers??? for possibly the wrong reason. =20 If the latter is true, and they use 16 Ga ( 10A rating) wire, as many pumps= =20 are wired, if there is a high draw from the pump, for whatever reason in= =20 excess of 10A but below 35 A, they may smell the toaster, not being aware = of=20 their possibly fatal flaw. A dead short may blow the breaker first, but it= =20 may cause various damages to the wiring bundle in which the pump leads=20 reside. =20 If the main electrical trunk is protected by a 35 A breaker/fuse, that only= =20 protects the main trunk, not the individual wires going to the pumps. =20 Rich =20 =20 =20 In a message dated 6/13/2012 10:32:56 P.M. Central Daylight Time, =20 hoursaway1@comcast.net writes: I didn't get a chance to respond to Ed's post yet. Yes they do have=20 separate elect., pump 2 is set up on a 35A breaker with an emergency power= =20 circuit , by-passing the master switch/solenoid & other elect., runs eng. = only. =20 Thanks Bill, David.=20 =20 ____________________________________ From: "Bill Bradburry" To: "Rotary motors in aircraft" Sent: Wednesday, June 13, 2012 10:07:02 PM Subject: [FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel=20 presure question. David,=20 If they don=E2=80=99t, each pump should have its own circuit, otherwise yo= u lose=20 your redundancy.=20 Bill B=20 =20 =20 ____________________________________ =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Mark Steitle Sent: Wednesday, June 13, 2012 8:24 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel=20 presure question. David, =20 =20 =20 Ed covered what I was thinking about a possible bad check-valve in one of= =20 your pumps. And a bunch of other stuff I hadn't considered. =20 =20 Mark =20 =20 On Wed, Jun 13, 2012 at 6:17 PM, Ed Anderson <_eanderson@carolina.rr.com_= =20 (mailto:eanderson@carolina.rr.com) > wrote:=20 =20 =20 David, don't know whether you have considered this - as you are aware the= =20 two pumps are able to work in parallel because the pumps have check valves= .=20 So if one pump is off and the other on, the on pump does not pump fuel=20 backwards through the off pump. Since each pump produces the 42 psi press= ure=20 by itself, one would assume the pumping elements in both pumps are working= =20 properly. Also assuming the pressure change is NOT due to a=20 malfunctioning pressure sensor. =20 =20 Here are some things that you might want to consider: =20 =20 1. That somehow when both pumps are on - one of the pumps check valves is= =20 not closing properly. Not a pump expert so not certain this could even= =20 happen - but the thought occurred to me. =20 =20 2. The effect of Increased fuel flow rate due to both pumps may be=20 causing a pressure drop through an upstream orifice (like perhaps your "T"= ). =20 =20 3. Turning on both pumps (assuming on the same circuit) might cause=20 sufficient voltage drop in the line sufficient to decrease the pumping=20 performance of both pumps - pump flow rates are sensitive to voltage varia= tions. =20 =20 4. The pressure return regulator might be malfunctioning and opening due= =20 to the higher flow rate - easy to check, just temporarily block off the=20 return. If the symptom disappears then it=E2=80=99s the regulator. =20 =20 =20 Theoretically, if the fuel flow rate through the T's and pumps does not= =20 change with both pumps on, then the pressure should remain the same - whi= ch=20 is what you are expecting, but not seeing. =20 =20 =20 So since the pressure does change (drops) - what could cause this=20 (assuming the pressure drop is real and not the result some strange malfun= ction of=20 your gauge)? =20 =20 One thing that could cause it, is if the fuel flow rate increases through= =20 an upstream orifice in your fuel line (say at the "T" which feeds your two= =20 pumps) then the pressure on the other (downstream) side will drop. Turn= =20 one of the pumps off, the fuel flow rate drops, therefore there is less=20 pressure drop across this orifice and your fuel pressure on the downstrea= m=20 side of the orifice will again go up. =20 =20 Its similar to a resistor in a circuit. The resistor value will remain=20 static - the same, but if you pull more current thought it, the voltage dr= op=20 across it will increase resulting in less voltage on the downstream side. = =20 Reduce the current flow back to previous rate and the voltage drop across= =20 the resistor decreases and therefore voltage on the downstream side =20 increase. =20 =20 Another possible cause might be if both of your pumps are fed off the same= =20 electrical line and there is sufficient resistance that when both pumps=20 are on the voltage drop causes less performance by both pumps. =20 =20 Just some WAGs that you might consider, if the suggestions make by others= =20 do not result in identifying the cause. =20 =20 Good Luck =20 =20 Ed =20 =20 Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 _http://www.andersonee.com_ (http://www.andersonee.com/)=20 _http://www.eicommander.com_ (http://www.eicommander.com/)=20 =20 =20 =20 =20 From: _hoursaway1@comcast.net_ (mailto:hoursaway1@comcast.net) =20 =20 Sent: Wednesday, June 13, 2012 6:43 PM =20 To: _Rotary motors in aircraft_ (mailto:flyrotary@lancaironline.net) =20 =20 Subject: [FlyRotary] Re: Fuel presure question. =20 =20 Fuel is gravity routed from tanks to ganged fuel selector out to T-fitting= =20 with each pump on the sides of the T, to another T, into main line out= =20 to eng., pressure sender is mounted directly after the T where the two=20 pumps come together. All this is in front of the wing spar near the floo= r in =20 an RV6A. This would make the pumps in parallel & the pressure is the same = =20 from either pump, but both together pressure drops. David =20 =20 ____________________________________ =20 From: "Mark Steitle" _msteitle@gmail.com_ (mailto:msteitle@gmail.com)=20 To: "Rotary motors in aircraft" <_flyrotary@lancaironline.net_=20 (mailto:flyrotary@lancaironline.net) > Sent: Wednesday, June 13, 2012 8:36:19 AM Subject: [FlyRotary] Re: Fuel presure question. David, How are your pumps plumbed... in parallel or series? What kind of pressure do you get when running the backup pump only? Mark On 6/13/12, Tracy <_rwstracy@gmail.com_ (mailto:rwstracy@gmail.com) > wrote= : > Hmmmm... Mine goes up about a pound when I switch on the second pump. = =20 What > happens when you turn both off? > > Tracy > > Sent from my iPad > > On Jun 12, 2012, at 7:11 PM, _hoursaway1@comcast.net_=20 (mailto:hoursaway1@comcast.net) wrote: > >> Question about fuel pressure indications, at fast idle 2200 RPM, fuel >> pressure is 42 PSI on EM2, if I switch on the back-up pump with the >> primary pump the pressure drops to 35 PSI, can here both pumps running,= =20 if >> I switch off either pump pressure goes back to 42 PSI. My system is 13B= , >> stock red injectors all four, pressure regulator is stock Mazda on the= =20 end >> of fuel rail with vacume connection from dynamic chamber. Thanks, =20 David >> R. Cook RV6A Rotary. > -- Homepage: _http://www.flyrotary.com/_ (http://www.flyrotary.com/)=20 Archive and UnSub: =20 _http://mail.lancaironline.net:81/lists/flyrotary/List.html_ (http://mail.l= ancaironline.net:81/lists/flyrotary/List.html)=20 No virus found in this message. Checked by AVG - _www.avg.com_ (http://www.avg.com/)=20 Version: 2012.0.2180 / Virus Database: 2433/5068 - Release Date: 06/13/12 --part1_3e3ad.2da8b56a.3d0b571d_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
OOOOOOO,
 
A 35 A breaker--- for the pump???
 
Since the breaker is supposed to protect the wire from heat rise and= =20 eventual fire, not the pump, that kind of amperage rating is appropriate fo= r a=20 10 Ga wire for short periods of time (a 30A rating) or 8 Ga continuous= (a=20 40A rating). The rating of wire is based on heat-rise, (I think it is 25*C = in=20 bundled wire). The rating increases if the wire is well ventilated and not= =20 bundled, or is overloaded for short periods of time such as smaller gauge, = than=20 appropriate, used in a starter circuit. The heat comes from the resistance = of=20 the wire to the electric flow. This resistance decreases with=20 decreasing Gauge.
 
Is he/are they really running that kind of wire to their pumps or do t= hey=20 just uprate the breakers??? for possibly the wrong reason.
 
If the latter is true, and they use 16 Ga ( 10A rating) wire, as many = pumps=20 are wired, if there is a high draw from the pump, for whatever reason in ex= cess=20 of 10A but below 35 A, they may smell the toaster, not being aware of their= =20 possibly fatal flaw. A dead short may blow the breaker first, but it may ca= use=20 various damages to the wiring bundle in which the pump leads reside.
 
If the main electrical trunk is protected by a 35 A breaker/fuse, that= only=20 protects the main trunk, not the individual wires going to the pumps.
 
Rich
 
 
In a message dated 6/13/2012 10:32:56 P.M. Central Daylight Time,=20 hoursaway1@comcast.net writes:
=
I = ;didn't=20 get a chance to respond to Ed's post yet. Yes they do have separate elect= .,=20 pump 2 is set up on a 35A breaker with an emergency power circuit , by-pa= ssing=20 the master switch/solenoid & other elect., runs eng. only. =20 Thanks  Bill,  David. 

From: "Bill Bradburry" <bbradburry@bellsouth.net>
To:= =20 "Rotary motors in aircraft"=20 <flyrotary@lancaironline.net>
Sent: Wednesday, June 13, 2= 012=20 10:07:02 PM
Subject: [FlyRotary] Re: Two possible causes was := =20 [FlyRotary] Re: Fuel presure question.

David,<= /FONT>

=  

If they don=E2= =80=99t, each=20 pump should have its own circuit, otherwise you lose your=20 redundancy.

=  

Bill=20 B

=  

From: Rotary=20 motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Wednesday, June 13, 2012 8:2= 4=20 PM
To: Rotary motors i= n=20 aircraft
Subject: [Fly= Rotary]=20 Re: Two possible causes was : [FlyRotary] Re: Fuel presure=20 question.

 

David, 

 

Ed covered what I was thinking about a possible= bad=20 check-valve in one of your pumps.  And a bunch of other stuff I hadn= 't=20 considered.

 

Mark 

On Wed, Jun 13, 2012 at 6:17 PM, Ed Anderson &l= t;eanderson@carolina.rr.com> wrote:

David, don't know whether y= ou have=20 considered this - as you are aware the two pumps are able to work in para= llel=20 because the pumps have check valves.  So if one pump is off and the = other=20 on, the on pump does not pump fuel backwards through the off pump.  = Since=20 each pump produces the 42 psi pressure by itself, one would assume the pu= mping=20 elements in both pumps are working properly.  Also assuming the pres= sure=20 change is NOT due to a malfunctioning pressure sensor.

<= /DIV>

 

Here are some things that y= ou=20 might want to consider:

 

1.  That somehow when = both=20 pumps are on - one of the pumps check valves is not closing properly.&nbs= p;=20 Not a  pump expert so not certain this could even happen - but the= =20 thought occurred to me.

 

2.  The effect of Incr= eased=20 fuel flow rate due to both pumps may be causing a pressure drop= =20 through an upstream orifice (like perhaps your "T").

 

3.  Turning on both pu= mps=20 (assuming on the same circuit) might cause sufficient voltage drop in the= line=20 sufficient to decrease the pumping performance of both pumps - pump flow = rates=20 are sensitive to voltage variations.

 

4.  The pressure retur= n=20 regulator might be malfunctioning and opening due to the higher flow rate= -=20 easy to check, just temporarily block off the return.  If the sympto= m=20 disappears then it=E2=80=99s the regulator.

 

 

Theoretically, if the fuel = flow=20 rate through the T's and pumps  does not change with both pumps on, = then=20 the pressure should remain the same  - which is what you are expecti= ng,=20 but not seeing. 

 

So since the pressure does = change=20 (drops) - what could cause this (assuming the pressure drop is real and n= ot=20 the result some strange malfunction of your gauge)?

 

  One thing that could= cause=20 it, is if the fuel flow rate increases through an upstream orifice i= n=20 your fuel line (say at the "T" which feeds your two pumps)  the= n the=20 pressure on the other (downstream) side will drop.  Turn one of the = pumps=20 off, the fuel flow rate drops, therefore there is less pressure drop acro= ss=20 this orifice  and your fuel pressure on the downstream side of the= =20 orifice will again go up.

 

Its similar to a resistor i= n a=20 circuit.  The resistor value will remain static - the same, but if y= ou=20 pull more current thought it, the voltage drop across it will increase=20 resulting in less voltage on the downstream side.  Reduce the curren= t=20 flow back to previous rate and the voltage drop across the resistor= =20 decreases and therefore voltage on the downstream side=20 increase.

 

Another possible cause migh= t be if=20 both of your pumps are fed off the same electrical line and there is=20 sufficient resistance that when both pumps are on the voltage drop causes= less=20 performance by both pumps.

 

Just some WAGs that yo= u might=20 consider, if the suggestions make by others do not result in identifying = the=20 cause.

 

Good Luck

=

 

Ed

 

Edward L. Anderson
Ander= son=20 Electronic Enterprises LLC
305 Reefton Road
Weddington, NC 28104http://www.andersonee.com
http://www.eicommander.com

 

From: hoursaway1@comcast.net

Sent:=20 Wednesday, June 13, 2012 6:43 PM

To: Rotary motors= in=20 aircraft

Subject= :=20 [FlyRotary] Re: Fuel presure question.

 

Fuel is gravity routed from= tanks=20 to ganged fuel selector out to T-fitting with each pump on the sides of t= he=20 T,  to another T,  into main line out to eng., pressure se= nder=20 is mounted directly after the T  where the two pumps come=20 together.   All this is in front of the wing spar near the floo= r in=20 an RV6A. This would make the pumps in parallel & the pressure is the = same=20 from either pump, but both together pressure drops.  =20 David 

From:=20 "= Mark=20 Steitle" msteitle@gmail.com
To:=20 "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, June 13, 2012 8:3= 6:19=20 AM
Subject: [FlyRotary= ] Re:=20 Fuel presure question.

David,

How are your pumps plumbed...= in=20 parallel or series?  What kind of
pressure do you get when runnin= g the=20 backup pump only?

Mark

On 6/13/12, Tracy <rwstracy@gmail.com> wrote:
> Hmmmm...  = Mine=20 goes up about a pound when I switch on the second pump.  What
>= ;=20 happens when you turn both off?
>
> Tracy
>
> Sen= t=20 from my iPad
>
> On Jun 12, 2012, at 7:11 PM, hoursaway1@comcast.net wrote:
>
>> Que= stion=20 about fuel pressure indications, at fast idle 2200 RPM, fuel
>>= =20 pressure is 42 PSI on EM2, if I switch on the back-up pump with=20 the
>> primary pump the pressure drops to 35 PSI, can here both = pumps=20 running, if
>> I switch off either pump pressure goes back to 42= PSI.=20  My system is 13B,
>> stock red injectors all four, pressur= e=20 regulator is stock Mazda on the end
>> of fuel rail with vacume= =20 connection from dynamic chamber.  Thanks,  David
>> R.= Cook=20  RV6A Rotary.
>

--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:  = ; http://mail.lancaironline.net:81/lists/flyrotary/List.htm= l

www.avg.com
Version:= =20 2012.0.2180 / Virus Database: 2433/5068 - Release Date:=20 06/13/12

 

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