X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 27 Oct 2011 09:36:16 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-mealy.atl.sa.earthlink.net ([209.86.89.69] verified) by logan.com (CommuniGate Pro SMTP 5.4.2) with ESMTP id 5174091 for lml@lancaironline.net; Wed, 26 Oct 2011 23:35:41 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.69; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=UFRH6Sdio7Rvn6C67r2AcWOAmzngtCePo+fhlxg0rVltnMQNEA35+uDXU4GZYY99; 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 [64.223.218.240] (helo=[192.168.1.25]) by elasmtp-mealy.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1RJGkF-0006J5-41 for lml@lancaironline.net; Wed, 26 Oct 2011 23:35:07 -0400 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-232--70593260 Subject: Re: [LML] Re: Problem with Fluctuating Amperage X-Original-Date: Wed, 26 Oct 2011 23:35:06 -0400 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1084) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da9406974decf9e53e165d7d40ce315112643350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 64.223.218.240 --Apple-Mail-232--70593260 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii David, I had a problem with my GRT EIS that shares with your situation the = possibility that something bad happening on one channel of the EIS is = affecting some other channels on the EIS. In my case, one of my spade = connectors in my EIS harness poked through to ground with the result = that my tach went to zero. The solution in my case was to disassemble = the entire EIS sensor wire bundle and put it back together with special = care that nothing could ever poke through to anything else. If it were my airplane I think I would first wire up a temporary = ammeter/shunt and verify that your electrical system is okay. Then I would start disconnecting things on the EIS sensor bundle until I = found the culprit. Colyn On Oct 26, 2011, at 9:56 AM, Charley Brown wrote: Yeah, that's what I'm thinking. Steady voltage and wildly fluctuating = amps in a simple system like that just cannot both be true. = Possibilities: 1. Ammeter is not correctly calibrated, and the actual swings are a lot = smaller? But actually, the 15 amp value seems reasonable in a 12V = system; my 28V system pulls about 8-9A when the big loads are off (pitot = heat, landing lights). 2. The fact this effect cycles regularly, and doesnt occur for a while = in the first place, suggests a heat-related problem -- regulator heating = up, shutting off, cooling down, starts to work again, heats up, shuts = off, cools down...? But like the other guys said -- check the wires first. =20 Thoughts worth what you paid for them. CB On Oct 26, 2011, at 5:21 AM, Dennis Johnson wrote: If the voltage is steady at 13.8 while the amperage is fluctuating from = plus 15 amps to minus 50 amps, then either the voltmeter is broken or = the amperage reading is incorrect. My guess is the amperage reading is = wrong. Is there some kind of electromagnetic interference that is = causing the amp reading and the fuel gauges to go haywire at the same = time? Is the hydraulic pump cycling every five minutes and doing this? = I don't think hydraulic pumps are common antagonists, but I can't think = of anything else that might cycle every five minutes. It's always a = good idea to check grounds, but my guess is EMI. =20 Interesting problem! =20 Dennis ----- Original Message ----- From: Taylor, David To: lml@lancaironline.net Sent: Tuesday, October 25, 2011 6:00 PM Subject: [LML] Re: Problem with Fluctuating Amperage Voltage reads steady at 13.8 volts. Amp drop is on the EIS unit, so the = EFIS unit is not the cause. Good idea on downloading data. =20 Dave T. =20 From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = Dennis Johnson Sent: 10-25-11-Tue 14:01 To: lml@lancaironline.net Subject: [LML] Re: Problem with Fluctuating Amperage =20 Hi David, =20 What is the voltage reading during this time? Does the Grand Rapids = EFIS Sport record data that you can download and study after a flight?=20= =20 Dennis Legacy 450 hours ----- Original Message ----- From: Taylor, David To: lml@lancaironline.net Sent: Tuesday, October 25, 2011 4:50 AM Subject: [LML] Problem with Fluctuating Amperage =20 Any ideas about what would cause my amperage to start fluctuating wildly = about 5 minutes into a flight?=20 It starts out fine after takeoff at 15 amps and then goes to -50 amps = for 30 seconds, and then gyrates between 5 amps and -50 amps for a = minute and then goes back to normal. It repeats this sequence every 5 = minutes.=20 My fuel gages also go down to zero during this episode and then back to = normal. Is my B&C LR3C Linear Regulator going bad?=20 (I'm getting these readings from my Grand Rapids EIS engine monitor. = It's hooked up to a Grand Rapids EFIS Sport.) Thanks for the help! David T. Legacy RG =20 --Apple-Mail-232--70593260 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii
If = the voltage is steady at 13.8 while the amperage is fluctuating from = plus 15 amps to minus 50 amps, then either the voltmeter is broken or = the amperage reading is incorrect.  My guess is the amperage = reading is wrong.  Is there some kind of electromagnetic = interference that is causing the amp reading and the fuel gauges to go = haywire at the same time?  Is the hydraulic pump cycling every five = minutes and doing this?  I don't think hydraulic pumps are common = antagonists, but I can't think of anything else that might cycle every = five minutes.  It's always a good idea to check grounds, but my = guess is EMI.
 
Interesting = problem!
 
Dennis
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