X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 04 Sep 2012 16:18:53 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-kukur.atl.sa.earthlink.net ([209.86.89.65] verified) by logan.com (CommuniGate Pro SMTP 6.0c1) with ESMTP id 5742968 for lml@lancaironline.net; Tue, 04 Sep 2012 09:51:04 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.65; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=Oh5+ZVhqU/HwH6PBmi/dOpP6nVx0QHFrBJe4EM0LxWdaFzuQDrSd4fmttZcaZ/YA; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [64.222.105.151] (helo=[192.168.1.24]) by elasmtp-kukur.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1T8tWE-0001Bg-MG for lml@lancaironline.net; Tue, 04 Sep 2012 09:50:18 -0400 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-554--907769029 Subject: Re: [LML] Re: Thermal influence on Hydraulic Pressure X-Original-Date: Tue, 4 Sep 2012 09:50:18 -0400 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <4C7FE048-2675-45A2-B094-4502028A8820@earthlink.net> X-Mailer: Apple Mail (2.1084) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da94094e96917db8d3054bbcb8d7e7d4b18d1350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 64.222.105.151 --Apple-Mail-554--907769029 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Tell us more about those hydraulic speed brakes... On Sep 3, 2012, at 2:54 PM, Frederick Moreno wrote: I have an MPV-50 engine monitor that includes continuous reading of the = hydraulic system pressure on my Lancair IV/ I have seen the same = thing, particularly on a flight that started on a cool morning departure = from my home drome and took us to the desert for a 110+F day. On = descent, pressure rose from its customary 1250 to 1500 psi at which = point Bitching Betty started to complain so I bumped my speed brakes = which are hydraulic, and lowered pressure back down to my customary = range. Same thing sometimes happens in reverse, a hot soak on the = ground, then a climb to 10-11,000 feet for a cool soak, and at some = point the hydraulic pump kicks on to restore pressure to the desired = level. My TR-182 used to the the same thing routinely when departing = Phoenix in the summertime. =20 It is a real effect, and makes one wonder about very high pressure = events arising from FL 270 (say) cold soak terminating in Phoenix on a = July afternoon. Hmmmm.... =20 Fred =20 =20 =20 =20 -------Original Message------- =20 =20 -took this photo after a descent from 16.5k to 1,500 ft. OAT went from 42 to 94 degrees. High Pressure gauge is pegged at 2,000+ psi -Didn't get a photo, but the opposite happened on the ramp in Spokane. = After sitting for an hour, the low pressure gauge was pegged at 1,200 = psi+. Spokane might not be the warmest spot in the country, but at 85 = deg F, it was 55 degrees warmer than the cold soak on the previous leg. Temperature changes have a big impact on system pressure.=20 =20 Chris Zavatson N91CZ 360std http://www.n91cz.net/ =20 --Apple-Mail-554--907769029 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii Tell us more about those hydraulic speed = brakes...

On Sep 3, 2012, at 2:54 PM, Frederick Moreno = wrote:

I = have an MPV-50  engine monitor that includes continuous reading of = the hydraulic system pressure on my Lancair IV/    I have = seen the same thing, particularly on a flight that started on a cool = morning departure from my home drome and took us to the desert for a = 110+F day.  On descent, pressure rose from its customary 1250 to = 1500 psi at which point Bitching Betty started to complain so I bumped = my speed brakes which are hydraulic, and lowered pressure back down = to my customary range.   Same thing sometimes happens in = reverse, a hot soak on the ground, then a climb to 10-11,000 feet for a = cool soak, and at some point the hydraulic pump kicks on to restore = pressure to the desired level.  My TR-182 used to the the same = thing routinely when departing Phoenix in the = summertime.
 
It is a real effect, and makes = one wonder about very high pressure events arising from FL 270 (say) = cold soak terminating in Phoenix on a July afternoon.  = Hmmmm....
 
Fred
 
 = ;
 
 
-------Original = Message-------
 
 
-took this = photo after a descent from 16.5k to 1,500 ft.
OAT went from 42 to 94 degrees.
High Pressure gauge is pegged at 2,000+ = psi
-Didn't get a photo, but the = opposite happened on the ramp in Spokane. After sitting for an = hour, the low pressure gauge was pegged at 1,200 psi+.  Spokane = might not be the warmest spot in the country, but at 85 deg F, it was 55 = degrees warmer than the cold soak on the previous leg.
Temperature changes have a big impact on system = pressure. 
 
Chris Zavatson
360std
 
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