X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 29 Dec 2007 10:44:41 -0500 Message-ID: X-Original-Return-Path: Received: from mail13.syd.optusnet.com.au ([211.29.132.194] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTPS id 2623828 for lml@lancaironline.net; Sat, 29 Dec 2007 07:30:04 -0500 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.194; envelope-from=fredmoreno@optusnet.com.au Received: from fred ([202.139.5.198]) (authenticated sender fredmoreno) by mail13.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id lBTCT40L024897 for ; Sat, 29 Dec 2007 23:29:13 +1100 From: "Fred Moreno" X-Original-To: "Lancair Mail" Subject: FW: Redundancy and Electronic Reliability - Avionics Master X-Original-Date: Sat, 29 Dec 2007 21:29:12 +0900 X-Original-Message-ID: <019c01c84a16$72298a00$c6058bca@fred> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_019D_01C84A61.E2113200" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6822 Thread-Index: AchKCoGJlnIIOfVeSBaNLzs3+E0rEQACv11w X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_019D_01C84A61.E2113200 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable =20 How many of us have an avionics master system that if it fails will take = out way too much? =20 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. =20 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. =20 How does the Avionics master switch work in your plane? What happens if something simple happens like the control wire breaks. =20 _____ =20 All excellent questions. My approach (not the best, but the best I = could think of at the time): 1) I have dual busses and dual alternators that feed an essential = buss via diodes.=20 2) I have an avionics switch. But it is double pole, so I can = select power from the A buss or the B buss. Diode feed from either A or B is probably simpler and automatic. I also have a cross feed relay. 3) In case the A buss relay or B bus relay fail, my sequence is load shedding, and then to feed power to the failed bus via a by pass switch running through a 30 amp fuse. Thus I can also fly with both A and B = buss relays out (to save power) and operate at reduced load with the manual switch bypass. I labelled this switch "Emergency Power." Call me = paranoid, but relays (and that means big relays including contactors) do fail.=20 =20 So I have two ways to feed to each buss, and two ways to supply power to = the avionics buss and the essential buss. =20 Paranoid Fred ------=_NextPart_000_019D_01C84A61.E2113200 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 

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.

 

All excellent questions.  My = approach (not the best, but the best I could think of at the = time):

1)     I have dual busses and dual = alternators that feed an essential buss via diodes.

2)     I have an avionics switch.  = But it is double pole, so I can select power from the A buss or the B = buss.  Diode feed from either A or B is probably simpler and automatic. =   I also have a cross feed relay.

3)     In case the A buss relay or B = bus relay fail, my sequence is load shedding, and then to feed power to the failed = bus via a by pass switch running through a 30 amp fuse.  Thus I can = also fly with both A and B buss relays out (to save power) and operate at reduced = load with the manual switch bypass.  I labelled this switch = “Emergency Power.”  Call me paranoid, but relays (and that means big = relays including contactors) do fail.

 

So I have two ways to feed to each = buss, and two ways to supply power to the avionics buss and the essential = buss.

 

Paranoid Fred

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