X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Received: from ms-smtp-02.southeast.rr.com ([24.25.9.101] verified) by logan.com (CommuniGate Pro SMTP 5.1.4) with ESMTP id 1714703 for flyrotary@lancaironline.net; Mon, 25 Dec 2006 19:48:16 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-100-190.carolina.res.rr.com [24.74.100.190]) by ms-smtp-02.southeast.rr.com (8.13.6/8.13.6) with SMTP id kBQ0lTbJ009873 for ; Mon, 25 Dec 2006 19:47:30 -0500 (EST) Message-ID: <002501c72887$734c6170$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: fuel pumps Date: Mon, 25 Dec 2006 19:47:41 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0022_01C7285D.8A2A0E30" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0022_01C7285D.8A2A0E30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageI am "almost" inclined to agree with you, Rusty. I have had my = two pumps since 1998 and found that if you block off the pressure = regulator you should get around 80 psi on a brand new pump. As they = wear/age this no-flow pressure will slowly start to decrease. My "main" = pump is now down to 60 psi while the back-up (only used for take off and = landing) is still producing 80 psi. However, I had to replace on of the original pumps after only 30 hours = of test stand running. It simply would not produce pressure. I now = wish I had taken it apart to see what the problem was. It was not the = check valve, because pressure was maintained when the other pump was on. = The pump could be hear running - so I suspect that the impeller had = sheared a pin or something of the sort. So , my "however" is = regarding the fact that most things have an "infant" morality period - = which once you make it through provides a high probably of a long- long = life. I suspect pumps are the same. My point is having an "infant mortality" incident in a aircraft is far = different than say - in a car (as we all know). FWIW Ed ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Monday, December 25, 2006 5:39 PM Subject: [FlyRotary] Re: fuel pumps A single pump system=20 is a non starter in aircraft.=20 Lynn E. Hanover Hi Lynn, Funny you should mention this, because I've actually been = contemplating a single pump system on the single rotor. These pumps are = quite reliable, and seem to give lower readings as they start to wear. = I could probably argue that all the extra plumbing and wiring might = cause more problems than it avoids. Also, no one seems to mind running = a single regulator, but that could fail just as easily. =20 One thing I keep thinking about is a conversation I keep having with a = couple RV buddies. One guys wants an auto conversion, but only if it's = as reliable as his car. The thought being that you get in your car and = drive thousands of miles, and don't ever consider what whether the = engine might break on the way there. Using a modern car as the = reliability standard, you have to accept that there is only one of = everything (ECU, fuel pump, etc). =20 BTW, just to let you know how abby-normal I think, I used to run both = pumps all the time, just as I also run my boost pump (almost) all the = time for the Lycoming. My logic is that I'd rather find out about a = pump failure when I'm safely on the ground, checking them individually = during my run-up. =20 I'm certainly not telling anyone to take out their backup pump, but = I'm wondering if I might just leave mine out.=20 Cheers, Rusty (attached pic for Lynn ) -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_0022_01C7285D.8A2A0E30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
I am "almost" inclined to agree with you, = Rusty.  I have=20 had my two pumps since 1998 and found that if you block off the pressure = regulator you should get around 80 psi on a brand new pump.  As = they=20 wear/age this no-flow pressure will slowly start to decrease.  My = "main"=20 pump is now down to 60 psi while the back-up (only used for take off and = landing) is still producing 80 psi.
 
However, I had to replace on of the original pumps = after only=20 30 hours of test stand running.  It simply would not produce=20 pressure.  I now wish I had taken it apart to see what the problem=20 was.  It was not the check valve, because pressure was maintained = when the=20 other pump was on.  The pump could be hear running - so I suspect = that the=20 impeller had sheared a pin or something of the sort.  So , my=20 "however"   is regarding the fact that most things have an = "infant"=20 morality period - which once you make it through provides a high = probably of a=20 long- long life.  I suspect pumps are the same.
 
  My point is having an "infant mortality" = incident in a=20 aircraft is far different than say - in a car (as we all = know).
 
FWIW
 
Ed
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Monday, December 25, 2006 = 5:39=20 PM
Subject: [FlyRotary] Re: fuel = pumps

 A single = pump system=20
is a non starter in aircraft. 
 
Lynn E. Hanover
 
Hi=20 Lynn,
 
Funny you=20 should mention this, because I've actually been contemplating a single = pump=20 system on the single rotor.  These pumps are quite reliable, and = seem to=20 give lower readings as they start to wear.  I could probably = argue=20 that all the extra plumbing and wiring might cause more problems = than it=20 avoids.   Also, no one seems to mind running a single = regulator, but=20 that could fail just as easily.  
 
One thing=20 I keep thinking about is a conversation I keep having with a = couple=20 RV buddies.  One guys wants an auto conversion, but = only if=20 it's as reliable as his car.  The thought being that you get in = your car=20 and drive thousands of miles, and don't ever consider what = whether the=20 engine might break on the way there.  Using a modern car as the=20 reliability standard, you have to accept that there is only one of = everything=20 (ECU, fuel pump, etc).  
 
BTW, just to=20 let you know how abby-normal I think, I used to run both pumps = all the=20 time, just as I also run my boost pump (almost) all the time for = the=20 Lycoming.  My logic is that I'd rather find out about = a pump=20 failure when I'm safely on the ground, checking them individually=20 during my run-up.  
 
I'm certainly not telling anyone to take out = their backup=20 pump, but I'm wondering if I might just leave mine=20 out. 
 
Cheers,
Rusty (attached pic for Lynn=20 <g>)

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