X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 28 Dec 2007 21:03:12 -0500 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 5.2c4) with ESMTP id 2622644 for lml@lancaironline.net; Fri, 28 Dec 2007 09:19:16 -0500 Received-SPF: neutral receiver=logan.com; client-ip=209.86.89.65; envelope-from=mnewman@dragonnorth.com Received: from [70.91.142.49] (helo=PCmike2) by elasmtp-kukur.atl.sa.earthlink.net with asmtp (Exim 4.34) id 1J8G2m-0004lZ-4w for lml@lancaironline.net; Fri, 28 Dec 2007 09:18:36 -0500 From: "Michael Newman" X-Original-To: Subject: Redundancy and Electronic Reliability - Avionics Master X-Original-Date: Fri, 28 Dec 2007 09:19:11 -0500 Organization: Dragonnorth Group X-Original-Message-ID: <035201c8495c$9e24a640$0201a8c0@sentira.net> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0353_01C84932.B54E9E40" X-Mailer: Microsoft Office Outlook 11 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 thread-index: AchJXJwjhqceYUMDSEe2MzPq/tqfrQ== X-ELNK-Trace: 4981850a937e3365551c28c27865cf0a239a348a220c26099b2aac750fa1131a8921e5b333548f0e3ca473d225a0f487350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 70.91.142.49 This is a multi-part message in MIME format. ------=_NextPart_000_0353_01C84932.B54E9E40 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hidden in the last few posts has been a key insight that I would like to emphasize. It is often the simple things that fail and take out far more than is expected. An example is the brightness resistor in the EFIS system. Nobody ever thought it should be redundant. A example from my personal history involves an avionics master switch in my Bonanza. The system was dirt simple the avionics power was switched by a single 30 amp switch type circuit breaker. (Not even a switch and remote relay as is typical.) What happened was that the case of the breaker cracked and it no longer conducted electricity. All the avionics went dark. Happened in flight. The weather was good VFR and I simply flew home. I solved the problem in the Bonanza by adding a second breaker in parallel with an operational note to turn on only one at a time. How many of us have an avionics master system that if it fails will take out way too much? How about the panel master switch? In my Certified Bonanza there is such a switch that can take down all the electrons. With vacuum gyros this is probably OK. In my IV-P I had such a contactor, it is an all electric airplane. Having been burned once I now have two contactors that operate in parallel. The two panel split rocker switches that control the two alternators control the master contactors independently. How does the Avionics master switch work in your plane? What happens if something simple happens like the control wire breaks. _____ Michael Newman Dragonnorth Group 319 Dean Rd. Brookline, MA 02445 Cell: 617 821-4608 Home: 617 566-7975 Fax: 617 566-7975 www.dragonnorth.com mnewman@dragonnorth.com ------=_NextPart_000_0353_01C84932.B54E9E40 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
Hidden = in the last=20 few posts has been a key insight that I would like to emphasize. It is = often the=20 simple things that fail and take out far more than is=20 expected.
 
An = example is the=20 brightness resistor in the EFIS system. Nobody ever thought it should be = redundant.
 
A = example from my=20 personal history involves an avionics master switch in my Bonanza. The = system=20 was dirt simple the avionics power was switched by a single 30 amp = switch=20 type circuit breaker. (Not even a switch and remote relay as is = typical.)=20 What happened was that the case of the breaker cracked and it no longer=20 conducted electricity. All the avionics went dark. Happened in flight. = The=20 weather was good VFR and I simply flew home. I solved the problem in the = Bonanza=20 by adding a second breaker in parallel with an operational note to turn = on only=20 one at a time.
 
How = many of us have=20 an avionics master system that if it fails will take out way too=20 much?
 
How = about the panel=20 master switch? In my Certified Bonanza there is such a switch that can = take down=20 all the electrons. With vacuum gyros this is probably = OK.
 
In my = IV-P I had=20 such a contactor, it is an all electric airplane. Having been = burned once I=20 now have two contactors that operate in parallel. The two panel split = rocker=20 switches that control the two alternators control the master contactors=20 independently.
 
How = does the=20 Avionics master switch work in your plane? What happens if something = simple=20 happens like the control wire breaks.
 

Michael Newman

Dragonnorth=20 Group

319 Dean Rd.
Brookline, MA 02445

Cell: 617=20 821-4608
Home: 617 566-7975
Fax: 617 566-7975

www.dragonnorth.com

mnewman@dragonnorth.com
 
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