X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 02 Oct 2007 20:21:43 -0400 Message-ID: X-Original-Return-Path: Received: from mta16.adelphia.net ([68.168.78.211] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2363212 for lml@lancaironline.net; Mon, 01 Oct 2007 22:53:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=68.168.78.211; envelope-from=glcasey@adelphia.net Received: from [75.82.253.35] by mta16.adelphia.net (InterMail vM.6.01.05.04 201-2131-123-105-20051025) with ESMTP id <20071002025225.DUWD6229.mta16.adelphia.net@[75.82.253.35]> for ; Mon, 1 Oct 2007 22:52:25 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-38-385462402 X-Original-Message-Id: From: Gary Casey Subject: Re: fuel tank drains X-Original-Date: Mon, 1 Oct 2007 19:52:23 -0700 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.752.2) --Apple-Mail-38-385462402 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes; format=flowed I've had some first-hand experience with this: Once I had a Cherokee in a group of 10 that was stored in an "open" =20 hangar during the month of December when it rained the whole month. =20 The previous user left the tanks empty. Apparently the tanks =20 collected a lot of condensation (about a pint it turned out). When I =20= took it the temp was well below freezing and I got fuel from a truck =20 that had been parked outside. There was no trace of water in the =20 fuel. I flew it to Moline, which was above freezing and I filled it =20 from an underground tank. Still no significant water - I think the =20 water hadn't run to the bottom yet. Engine lost power in the soup at =20= altitude over Iowa City. My conclusion was that the vibration from =20 the engine gradually jiggled the water droplets to the bottom, when =20 they went into the gascolator, which happened to be in a box cooled =20 by outside air. The water froze on the filter screen shutting off =20 the fuel flow. The electric pump, being in series with the filter, =20 couldn't help. Later, I asked an engineer at Piper why they would =20 put the electric pump, which had an integral sump and filter, in =20 series instead of in parallel with the gascolator. The answer was =20 they felt that the mechanic might not drain the sump and check the =20 filter during the annual. Little consolation to me. Bottom line was =20= that the gascolator hung on to much of the water, possibly preventing =20= a much earlier and more complete power loss. I'll keep my (oversize, =20= by the way) gascolator, thank you. And now I rock the wings before =20 checking for water, especially in a Cessna. Regarding filters, Bendix had trouble deciding whether to put a =20 bypass around the inline filter in their system. At first they put a =20= bypass valve in it (actually the filter pushed itself off the seal =20 against a spring. They got sued because someone kept going with a =20 plugged filter until the crud plugged the nozzles. So they turned =20 the filter around so that it wouldn't bypass. They got sued because =20 the filter plugged and there was no emergency bypass. I think they =20 all have a bypass capability now. I would NOT put any extra hardware =20= upstream of the engine-driven pump. One could argue that a plugging =20 filter would just result in a power reduction, not a stopped engine. =20= However, the more likely failure mode might be a pressure drop across =20= the filter that would cause the engine pump to vapor lock, resulting =20 in a complete engine failure. Sure, there is an electric pump, but =20 only if the pilot turns it on quickly enough. And why add a filter =20 that is finer than the downstream orifices? I'll stick to the =20 standard hardware. On Sep 30, 2007, at 3:01 AM, Lancair Mailing List wrote: > > [You might comment on installing additional inline automotive (non-=20 > bypass) very fine filters upstream of gascolator. > > > Charlie K.] > > I=92m not sure what comment to make Charlie. Most cars are fuel =20 > injected with a high pressure fuel pump in the tank. They can =20 > overcome a substantial filter pressure drop. > > Most small aircraft suck fuel out of the tank relying on the small =20 > pressure difference between the vapor pressure of the fuel and the =20 > tank static pressure. My concern is that a small amount of water =20 > may fill the fine mesh pores and create enough pressure drop to =20 > stop fuel flow. > > I wonder if that might be a factor in Gene Long=92s mystery fuel flow =20= > interruption. > > Aircraft carburetors and fuel injection systems have fine screens =20 > in their inlets, but they are downstream of the aircraft fuel pump, =20= > so a much greater head pressure is available. > > I think it is best to minimize resistance to flow upstream of the =20 > fuel pump, what do you think? > > > Regards, > Bill Hannahan --Apple-Mail-38-385462402 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=WINDOWS-1252 I've had some first-hand = experience with this:
Once I had a Cherokee in a group of 10 that = was stored in an "open" hangar during the month of December when it = rained the whole month.=A0 The previous user left the tanks empty.=A0 = Apparently the tanks collected a lot of condensation (about a pint it = turned out).=A0 When I took it the temp was well below freezing and I = got fuel from a truck that had been parked outside.=A0 There was no = trace of water in the fuel.=A0 I flew it to Moline, which was above = freezing and I filled it from an underground tank.=A0 Still no = significant water - I think the water hadn't run to the bottom yet.=A0 = Engine lost power in the soup at altitude over Iowa City.=A0 My = conclusion was that the vibration from the engine gradually jiggled the = water droplets to the bottom, when they went into the gascolator, which = happened to be in a box cooled by outside air.=A0 The water froze on the = filter screen shutting off the fuel flow.=A0 The electric pump, being in = series with the filter, couldn't help.=A0 Later, I asked an engineer at = Piper why they would put the electric pump, which had an integral sump = and filter, in series instead of in parallel with the gascolator.=A0 The = answer was they felt that the mechanic might not drain the sump and = check the filter during the annual.=A0 Little consolation to me.=A0 = Bottom line was that the gascolator hung on to much of the water, = possibly preventing a much earlier and more complete power loss.=A0 I'll = keep my (oversize, by the way) gascolator, thank you.=A0 And now I rock = the wings before checking for water, especially in a = Cessna.

Regarding filters, Bendix = had trouble deciding whether to put a bypass around the inline filter in = their system.=A0 At first they put a bypass valve in it (actually the = filter pushed itself off the seal against a spring.=A0 They got sued = because someone kept going with a plugged filter until the crud plugged = the nozzles.=A0 So they turned the filter around so that it wouldn't = bypass.=A0 They got sued because the filter plugged and there was no = emergency bypass.=A0 I think they all have a bypass capability now.=A0 I = would NOT put any extra hardware upstream of the engine-driven pump.=A0 = One could argue that a plugging filter would just result in a power = reduction, not a stopped engine.=A0 However, the more likely failure = mode might be a pressure drop across the filter that would cause the = engine pump to vapor lock, resulting in a complete engine failure.=A0 = Sure, there is an electric pump, but only if the pilot turns it on = quickly enough.=A0 And why add a filter that is finer than the = downstream orifices?=A0 I'll stick to the standard = hardware.=A0

On Sep 30, 2007, at 3:01 AM, = Lancair Mailing List wrote:

=A0
[You might = comment on installing additional inline automotive (non-bypass)=A0very = fine filters upstream of gascolator.

=A0
Charlie K.]
=A0
I=92m not sure what = comment to make Charlie. Most cars are fuel injected with a high = pressure fuel pump in the tank. They can overcome a substantial filter = pressure drop.
=A0
Most small aircraft = suck fuel out of the tank relying on the small pressure difference = between the vapor pressure of the fuel and the tank static pressure. My = concern is that a small amount of water may fill the fine mesh pores and = create enough pressure drop to stop fuel flow.
=A0
I wonder if that = might be a factor in Gene Long=92s mystery fuel flow = interruption.
=A0
Aircraft carburetors and fuel injection systems have fine = screens in their inlets, but they are downstream of the aircraft fuel = pump, so a much greater head pressure is available.
=A0
I think it is best to = minimize resistance to flow upstream of the fuel pump, what do you = think?


Regards,
Bill Hannahan
=

= --Apple-Mail-38-385462402--