X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 15 Jun 2007 01:33:57 -0400 Message-ID: X-Original-Return-Path: Received: from msgmmp-3.gci.net ([209.165.130.13] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTP id 2103657 for lml@lancaironline.net; Fri, 15 Jun 2007 00:37:09 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.165.130.13; envelope-from=ogrady@gci.net Received: from [10.0.1.8] ([24.237.13.108]) by msgmmp-1.gci.net (Sun Java System Messaging Server 6.2-3.03 (built Jun 27 2005)) with ESMTPA id <0JJN008RUU4NKB80@msgmmp-1.gci.net> for lml@lancaironline.net; Thu, 14 Jun 2007 20:36:30 -0800 (AKDT) X-Original-Date: Thu, 14 Jun 2007 20:35:55 -0800 From: Thomas O'Grady Subject: Re: [LML] Boost Pump In-reply-to: X-Original-To: Lancair Mailing List X-Original-Message-id: MIME-version: 1.0 X-Mailer: Apple Mail (2.752.2) Content-type: multipart/alternative; boundary="Boundary_(ID_34Nbm8Co+PjwgnrnQZiIzw)" References: --Boundary_(ID_34Nbm8Co+PjwgnrnQZiIzw) Content-type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Content-transfer-encoding: 7BIT Cessna had a slightly different arrangement on at least some of the IO-520s. The switch is split with high and low sides. Low boost does just that and is used for starting. High boost is used for failure of the mechanical pump, but until the throttle is pushed about halfway in, it only provides low boost. I have not flow tested it. Tom O'Grady 69 Cessna U206D On Jun 14, 2007, at 5:50 PM, Dennis Johnson wrote: > "My question is: could the output of the two pumps combine and > overwhelm the return line causing pressure and thus fuel flow to go > out of limits?" > > Just to restate the report of the Bonanza crash, with a TSIO-520 > engine. A Beech test pilot found that taking off with the boost > pump on high resulted in a smooth running engine, but a perceptible > loss of power. He flew above the airport at full power at a safe > altitude and with the boost pump on high. He slowly reduced > manifold pressure. The engine became rough at 35" and suffered a > complete loss of power at 31". Moving the throttle back in did not > restart the engine and he recovered by turning off the boost pump. > The NTSB report said that the engine would quit at 24" manifold > pressure with the boost pump on high. > > The pilots who have recently reported their findings on the LML > support the first half of the above claim, that high boost at full > power does not kill the engine. But those findings don't > contradict the second part of the claim, that high boost will kill > the engine below either 31" MAP (Beech test pilot) or 24" (NTSB). > I'm not planning to test it in my airplane; I'll stay on the ground > and have a beer instead. > > Source: Flying magazine's Aftermath article September 2004. > > Best, > Dennis Johnson > Legacy > --Boundary_(ID_34Nbm8Co+PjwgnrnQZiIzw) Content-type: text/html; charset=ISO-8859-1 Content-transfer-encoding: quoted-printable Cessna had a slightly different = arrangement on at least some of the IO-520s.=A0 The switch is split with = high and low sides.=A0 Low boost does just that and is used for = starting.=A0 High boost is used for failure of the mechanical pump, but = until the throttle is pushed about halfway in, it only provides low = boost.=A0 I have not flow tested it.

Tom O'Grady
69 = Cessna U206D

On Jun 14, 2007, at 5:50 PM, Dennis = Johnson wrote:

"
=A0
Just to = restate the report of the Bonanza crash, with a TSIO-520 engine.=A0 A = Beech test pilot found that taking off with the boost pump on high = resulted in a smooth running engine, but a perceptible loss of = power.=A0=A0He=A0flew=A0above the airport at full power at=A0a safe = altitude and with the boost pump on high.=A0 He slowly reduced manifold = pressure.=A0 The engine became rough at 35" and suffered a complete loss = of power at 31".=A0 Moving the throttle back in did not restart the = engine and he recovered by turning off the boost pump.=A0 The NTSB = report said that the engine would quit at 24" manifold pressure with the = boost pump on high.
=A0
The pilots who = have recently reported their findings on the LML support the first half = of the above claim, that high boost at full power does not kill the = engine.=A0 But those findings don't contradict the second part of the = claim, that high boost will kill the engine below either 31" MAP (Beech = test pilot) or 24" (NTSB).=A0 I'm not planning to test it in my = airplane; I'll=A0stay on the ground and have a beer = instead.=A0=A0=A0
=A0
Source:=A0 = Flying magazine's article September = 2004.
=A0
Dennis = Johnson

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