X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qmta11.emeryville.ca.mail.comcast.net ([76.96.27.211] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTP id 5600657 for flyrotary@lancaironline.net; Thu, 14 Jun 2012 21:53:37 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.27.211; envelope-from=hoursaway1@comcast.net Received: from omta16.emeryville.ca.mail.comcast.net ([76.96.30.72]) by qmta11.emeryville.ca.mail.comcast.net with comcast id NRhX1j0021ZMdJ4ABRt16P; Fri, 15 Jun 2012 01:53:01 +0000 Received: from sz0081.ev.mail.comcast.net ([76.96.26.137]) by omta16.emeryville.ca.mail.comcast.net with comcast id NRt11j01B2xV6SL8cRt1Pz; Fri, 15 Jun 2012 01:53:01 +0000 Date: Fri, 15 Jun 2012 01:53:01 +0000 (UTC) From: hoursaway1@comcast.net To: Rotary motors in aircraft Message-ID: <1527548907.136557.1339725181527.JavaMail.root@sz0081a.emeryville.ca.mail.comcast.net> In-Reply-To: Subject: Re: [FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel presure qu... MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_136556_644455490.1339725181525" X-Originating-IP: [71.206.108.115] X-Mailer: Zimbra 6.0.13_GA_2944 (ZimbraWebClient - IE8 (Win)/6.0.13_GA_2944) ------=_Part_136556_644455490.1339725181525 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Yes Rich this is a single wire no bundle, without looking at the schematic = for the aircraft I think the wire size is 10G, direct to independant power = switch used as an emergency backup power supply for a gen. failure , bypass= all other elect. including master contactor/relay & runs eng. & pump #2.= =C2=A0 ( With no gen. ) running from batt. alone you have aprox. 30 min. of= eng. run time to land.=C2=A0 Sorry did not mean to freak you out.=C2=A0 Da= vid=20 ----- Original Message ----- From: ARGOLDMAN@aol.com=20 To: "Rotary motors in aircraft" =20 Sent: Thursday, June 14, 2012 11:02:53 AM=20 Subject: [FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel pre= sure qu...=20 OOOOOOO,=20 =C2=A0=20 A 35 A breaker--- for the pump???=20 =C2=A0=20 Since the breaker is supposed to protect the wire from heat rise and eventu= al fire, not the pump, that kind of amperage rating is appropriate for a 10= Ga wire for short periods of time (a 30A rating)=C2=A0or 8 Ga continuous (= a 40A rating). The rating of wire is based on heat-rise, (I think it is 25*= C in bundled wire). The rating increases if the wire is well ventilated and= not bundled, or is overloaded for short periods of time such as smaller ga= uge, than appropriate, used in a starter circuit. The heat comes from the r= esistance of the wire to the electric flow.=C2=A0This resistance=C2=A0decre= ases with decreasing Gauge.=20 =C2=A0=20 Is he/are they really running that kind of wire to their pumps or do they j= ust uprate the breakers??? for possibly the wrong reason.=20 =C2=A0=20 If the latter is true, and they use 16 Ga ( 10A rating) wire, as many pumps= are wired, if there is a high draw from the pump, for whatever reason in e= xcess of 10A but below 35 A, they may smell the toaster, not being aware of= their possibly fatal flaw. A dead short may blow the breaker first, but it= may cause various damages to the wiring bundle in which the pump leads res= ide.=20 =C2=A0=20 If the main electrical trunk is protected by a 35 A breaker/fuse, that only= protects the main trunk, not the individual wires going to the pumps.=20 =C2=A0=20 Rich=20 =C2=A0=20 =C2=A0=20 In a message dated 6/13/2012 10:32:56 P.M. Central Daylight Time, hoursaway= 1@comcast.net writes:=20 I=C2=A0didn't get a chance to respond to Ed's post yet. Yes they do have se= parate elect., pump 2 is set up on a 35A breaker with an emergency power ci= rcuit , by-passing the master switch/solenoid & other elect., runs eng. onl= y.=C2=A0 Thanks=C2=A0 Bill,=C2=A0 David.=C2=A0=20 ----- Original Message ----- From: "Bill Bradburry" =20 To: "Rotary motors in aircraft" =20 Sent: Wednesday, June 13, 2012 10:07:02 PM=20 Subject: [FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel pre= sure question.=20 David,=20 =C2=A0=20 If they don=E2=80=99t, each pump should have its own circuit, otherwise you= lose your redundancy.=20 =C2=A0=20 Bill B=20 =C2=A0=20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Mark Steitle=20 Sent: Wednesday, June 13, 2012 8:24 PM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel pre= sure question.=20 =C2=A0=20 David,=C2=A0=20 =C2=A0=20 Ed covered what I was thinking about a possible bad check-valve in one of y= our pumps. =C2=A0And a bunch of other stuff I hadn't considered.=20 =C2=A0=20 Mark=C2=A0=20 On Wed, Jun 13, 2012 at 6:17 PM, Ed Anderson < eanderson@carolina.rr.com > = wrote:=20 David, don't know whether you have considered this - as you are aware the t= wo pumps are able to work in parallel because the pumps have check valves.= =C2=A0 So if one pump is off and the other on, the on pump does not pump fu= el backwards through the off pump.=C2=A0 Since each pump produces the 42 ps= i pressure by itself, one would assume the pumping elements in both pumps a= re working properly.=C2=A0 Also assuming the pressure change is NOT due to = a malfunctioning pressure sensor.=20 =C2=A0=20 Here are some things that you might want to consider:=20 =C2=A0=20 1.=C2=A0 That somehow when both pumps are on - one of the pumps check valve= s is not closing properly.=C2=A0 Not a=C2=A0 pump expert so not certain thi= s could even happen - but the thought occurred to me.=20 =C2=A0=20 2.=C2=A0 The effect of Increased fuel flow rate due to both pumps=C2=A0may = be=C2=A0causing a pressure drop through an upstream orifice (like perhaps y= our "T").=20 =C2=A0=20 3.=C2=A0 Turning on both pumps (assuming on the same circuit) might cause s= ufficient voltage drop in the line sufficient to decrease the pumping perfo= rmance of both pumps - pump flow rates are sensitive to voltage variations.= =20 =C2=A0=20 4.=C2=A0 The pressure return regulator might be malfunctioning and opening = due to the higher flow rate - easy to check, just temporarily block off the= return.=C2=A0 If the symptom disappears then it=E2=80=99s the regulator.= =20 =C2=A0=20 =C2=A0=20 Theoretically, if the fuel flow rate through the T's and pumps=C2=A0 does n= ot change with both pumps on, then the pressure should remain the same=C2= =A0 - which is what you are expecting, but not seeing.=C2=A0=20 =C2=A0=20 So since the pressure does change (drops) - what could cause this (assuming= the pressure drop is real and not the result some strange malfunction of y= our gauge)?=20 =C2=A0=20 =C2=A0 One thing that could cause it, is if the fuel flow rate increases th= rough an upstream orifice=C2=A0in your fuel line (say at the "T" which=C2= =A0feeds your two pumps) =C2=A0then the pressure on the other (downstream) = side will drop.=C2=A0 Turn one of the pumps off, the fuel flow rate drops, = therefore there is less pressure drop across this orifice =C2=A0and your fu= el pressure on the downstream side of the orifice will again go up.=20 =C2=A0=20 Its similar to a resistor in a circuit.=C2=A0 The resistor value will remai= n static - the same, but if you pull more current thought it, the voltage d= rop across it will increase resulting in less voltage on the downstream sid= e.=C2=A0 Reduce the current flow back to previous rate=C2=A0and the voltage= drop across the resistor decreases and therefore voltage on the downstream= side increase.=20 =C2=A0=20 Another possible cause might be if both of your pumps are fed off the same = electrical line and there is sufficient resistance that when both pumps are= on the voltage drop causes less performance by both pumps.=20 =C2=A0=20 Just=C2=A0some WAGs that you might consider, if the suggestions make by oth= ers do not result in identifying the cause.=20 =C2=A0=20 Good Luck=20 =C2=A0=20 Ed=20 =C2=A0=20 Edward L. Anderson=20 Anderson Electronic Enterprises LLC=20 305 Reefton Road=20 Weddington, NC 28104=20 http://www.andersonee.com=20 http://www.eicommander.com=20 =C2=A0=20 From: hoursaway1@comcast.net=20 Sent: Wednesday, June 13, 2012 6:43 PM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Fuel presure question.=20 =C2=A0=20 Fuel is gravity routed from tanks to ganged fuel selector out to T-fitting = with each pump on the sides of the T,=C2=A0 to another T,=C2=A0 into main l= ine out to eng., pressure=C2=A0sender is mounted directly after the T=C2=A0= where the two pumps come together.=C2=A0=C2=A0 All this is in front of the= wing spar near the floor in an RV6A. This would make the pumps in parallel= & the pressure is the same from either pump, but both together pressure dr= ops.=C2=A0=C2=A0 David=C2=A0=20 From: "Mark Steitle" msteitle@gmail.com=20 To: "Rotary motors in aircraft" < flyrotary@lancaironline.net >=20 Sent: Wednesday, June 13, 2012 8:36:19 AM=20 Subject: [FlyRotary] Re: Fuel presure question.=20 David,=20 How are your pumps plumbed... in parallel or series? =C2=A0What kind of=20 pressure do you get when running the backup pump only?=20 Mark=20 On 6/13/12, Tracy < rwstracy@gmail.com > wrote:=20 > Hmmmm... =C2=A0Mine goes up about a pound when I switch on the second pum= p. =C2=A0What=20 > happens when you turn both off?=20 >=20 > Tracy=20 >=20 > Sent from my iPad=20 >=20 > On Jun 12, 2012, at 7:11 PM, hoursaway1@comcast.net wrote:=20 >=20 >> Question 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 the=20 >> primary pump the pressure drops to 35 PSI, can here both pumps running, = if=20 >> I switch off either pump pressure goes back to 42 PSI. =C2=A0My system i= s 13B,=20 >> stock red injectors all four, pressure regulator is stock Mazda on the e= nd=20 >> of fuel rail with vacume connection from dynamic chamber. =C2=A0Thanks, = =C2=A0David=20 >> R. Cook =C2=A0RV6A Rotary.=20 >=20 --=20 Homepage: =C2=A0 http://www.flyrotary.com/=20 Archive and UnSub: =C2=A0 http://mail.lancaironline.net:81/lists/flyrotary/= List.html=20 No virus found in this message.=20 Checked by AVG - www.avg.com=20 Version: 2012.0.2180 / Virus Database: 2433/5068 - Release Date: 06/13/12= =20 =C2=A0=20 ------=_Part_136556_644455490.1339725181525 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable <= div style=3D'font-family: Arial; font-size: 12pt; color: #000000'>
Yes R= ich this is a single wire no bundle, without looking at the schematic for t= he aircraft I think the wire size is 10G, direct to independant power switc= h used as an emergency backup power supply for a gen. failure, bypass all o= ther elect. including master contactor/relay & runs eng. & pump #2.=   ( With no gen. ) running from batt. alone you have aprox. 30 min. of= eng. run time to land.  Sorry did not mean to freak you out.  Da= vid
From: ARGOLDMAN@aol.com
To: "Rotary motors in aircraft" &l= t;flyrotary@lancaironline.net>
Sent: Thursday, June 14, 2012 1= 1:02:53 AM
Subject: [FlyRotary] Re: Two possible causes was : [Fl= yRotary] Re: Fuel presure qu...

OOOOOOO,
 
A 35 A breaker--- for the pump???
 
Since the breaker is supposed to protect the wire from heat rise and e= ventual fire, not the pump, that kind of amperage rating is appropriate for= a 10 Ga wire for short periods of time (a 30A rating) or 8 Ga continu= ous (a 40A rating). The rating of wire is based on heat-rise, (I think it i= s 25*C in bundled wire). The rating increases if the wire is well ventilate= d and not bundled, or is overloaded for short periods of time such as small= er gauge, than appropriate, used in a starter circuit. The heat comes from = the resistance of the wire to the electric flow. This resistance = decreases with decreasing Gauge.
 
Is he/are they really running that kind of wire to their pumps or do t= hey 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 are wired, if there is a high draw from the pump, for whatever reason= in excess of 10A but below 35 A, they may smell the toaster, not being awa= re of their possibly fatal flaw. A dead short may blow the breaker first, b= ut it may cause various damages to the wiring bundle in which the pump lead= s reside.
 
If the main electrical trunk is protected by a 35 A breaker/fuse, that= only 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, hour= saway1@comcast.net writes:
I d= idn't get a chance to respond to Ed's post yet. Yes they do have separate e= lect., pump 2 is set up on a 35A breaker with an emergency power circuit , = by-passing the master switch/solenoid & other elect., runs eng. only.&n= bsp; Thanks  Bill,  David. 

From: "Bill Bradburry" <bbradburry@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sen= t: Wednesday, June 13, 2012 10:07:02 PM
Subject: [FlyRotary] = Re: Two possible causes was : [FlyRotary] Re: Fuel presure question.

David,<= /P>

 <= /P>

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

 <= /P>

Bill B<= /P>

 <= /P>

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
<= SPAN style=3D"FONT-WEIGHT: bold">Sent: Wednesday, June 13, 2012 = 8:24 PM
To: Rotary motor= s in aircraft
Subject: [= FlyRotary] Re: Two possible causes was : [FlyRotary] Re: Fuel presure quest= ion.

 

David, 

 

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

 

Mark 

On Wed, Jun 13, 2012 at 6:17 PM, Ed Anderson <eanderson@carolina.rr.com> wrote:

David, don't know whether you have considered thi= s - as you are aware the two pumps are able to work in parallel because the= pumps have check valves.  So if one pump is off and the other on, the= on pump does not pump fuel backwards through the off pump.  Since eac= h pump produces the 42 psi pressure by itself, one would assume the pumping= elements in both pumps are working properly.  Also assuming the press= ure change is NOT due to a malfunctioning pressure sensor.

 

Here are some things that you might want to consi= der:

 

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

 

2.  The effect of Increased fuel flow rate d= ue to both pumps may be causing a pressure drop through an upstre= am orifice (like perhaps your "T").

 

3.  Turning on both pumps (assuming on the s= ame circuit) might cause sufficient voltage drop in the line sufficient to = decrease the pumping performance of both pumps - pump flow rates are sensit= ive to voltage variations.

 

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

 

 

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

 

So since the pressure does change (drops) - what = could cause this (assuming the pressure drop is real and not the result som= e strange malfunction of your gauge)?

 

  One thing that could cause it, is if the f= uel flow rate increases through an upstream orifice in your fuel line = (say at the "T" which feeds your two pumps)  then the pressure on= the other (downstream) side will drop.  Turn one of the pumps off, th= e fuel flow rate drops, therefore there is less pressure drop across this o= rifice  and your fuel pressure on the downstream side of the orifice w= ill again go up.

 

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

 

Another possible cause might be if both of your p= umps are fed off the same electrical line and there is sufficient resistanc= e that when both pumps are on the voltage drop causes less performance by b= oth pumps.

 

Just some WAGs that you might consider, if t= he suggestions make by others do not result in identifying the cause.

 

Good Luck

 

Ed

 

Edward L. Anderson
Anderson Electronic Enterpr= ises LLC
305 Reefton Road
Weddington, NC 28104
http= ://www.andersonee.com
http://www.eicommander.com

 

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

Subject: [FlyRotary] Re: Fuel presure que= stion.

 

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

From: "Mark Steitle" msteitle@gmail.com
To: "Rotary motors in aircraft" <flyr= otary@lancaironline.net>
Sen= t: Wednesday, June 13, 2012 8:36:19 AM
Subject: [FlyRotary] Re: Fuel presure question.
David,

How are your pumps plumbed... in parallel or series? &n= bsp;What kind of
pressure do you get when running the backup pump only?<= BR>
Mark

On 6/13/12, Tracy <rwstracy@gmail.com> wrote:
> Hmmmm...  Mine goes up about a pound when I switc= h on the second pump.  What
> happens when you turn both off?>
> Tracy
>
> Sent from my iPad
>
> On Ju= n 12, 2012, at 7:11 PM, hoursaway1@comcast.net wro= te:
>
>> Question about fuel pressure indications, at fast i= dle 2200 RPM, fuel
>> pressure is 42 PSI on EM2, if I switch on th= e back-up pump with the
>> primary pump the pressure drops to 35 P= SI, can here both pumps running, if
>> I switch off either pump pr= essure goes back to 42 PSI.  My system is 13B,
>> stock red i= njectors all four, pressure regulator is stock Mazda on the end
>>= of fuel rail with vacume connection from dynamic chamber.  Thanks, &n= bsp;David
>> R. Cook  RV6A Rotary.
>

--
Homep= age:  http://www.flyrotary.com/
Archive and UnSub:=   http://mail.lancaironline.net:81/lists/flyrotary/List.html<= /SPAN>

= No virus found in this message.
Checked by AVG - www.avg.com
Ver= sion: 2012.0.2180 / Virus Database: 2433/5068 - Release Date: 06/13/12

 

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