X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 09 Aug 2011 07:55:38 -0400 Message-ID: X-Original-Return-Path: Received: from vms173019pub.verizon.net ([206.46.173.19] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTP id 5086193 for lml@lancaironline.net; Mon, 08 Aug 2011 22:39:35 -0400 Received-SPF: none receiver=logan.com; client-ip=206.46.173.19; envelope-from=mnewman@dragonnorth.com Received: from PCMIKE3 ([unknown] [72.70.56.213]) by vms173019.mailsrvcs.net (Sun Java(tm) System Messaging Server 7u2-7.02 32bit (built Apr 16 2009)) with ESMTPA id <0LPN00J2G3CKNAK0@vms173019.mailsrvcs.net> for lml@lancaironline.net; Mon, 08 Aug 2011 21:38:49 -0500 (CDT) Reply-to: From: "Michael Newman" X-Original-To: "'Bill Harrelson'" X-Original-Cc: "'Lancair Mailing List'" References: In-reply-to: Subject: RE: [LML] Re: Fw: Re: Re-doing my panel - carefully thinking through failures X-Original-Date: Mon, 08 Aug 2011 22:38:44 -0400 X-Original-Message-id: <010f01cc563d$77cfe990$676fbcb0$@com> MIME-version: 1.0 Content-type: multipart/alternative; boundary="----=_NextPart_000_0110_01CC561B.F0BE4990" X-Mailer: Microsoft Office Outlook 12.0 Thread-index: AcxVEjq6pHblTSlJTU6UEcx081KAOgBKjZTQ Content-language: en-us This is a multi-part message in MIME format. ------=_NextPart_000_0110_01CC561B.F0BE4990 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit You have a pretty good setup BUT. I had an avionics master breaker (switch type) in my Bonanza that failed. What happened was that the housing cracked behind the panel. The switch failed open on an IFR flight when the housing was no longer able to hold the contacts together. Your DPST switch can fail in the same way and will fail open. Both sides will be open from this common mechanical cause. My solution was to put in two separate breaker switches in parallel. I turn only one on at a time. If one fails I can simply turn on the other. From: Bill Harrelson [mailto:n5zq@verizon.net] Sent: Sunday, August 07, 2011 10:57 AM To: lml@lancaironline.net Subject: Re: [LML] Re: Fw: Re: Re-doing my panel - carefully thinking through failures Bill, My avionics switch is a DPST switch. Basically two switches in one. Each side controls the power feed from one electrical system. Sure, both sides of the switch could fail at the same time but that would be unlikely. On top of that I have a separate, isolated switch that feeds power only to the GPS/Com so that even if both sides of the avionics switch should fail or both electrical system 1 and 2 fail, I can power this unit from system 3. System 3 is an 8 amp B&C generator and an Odyssey 545 battery. Bill Harrelson N5ZQ 320 1,950 hrs N6ZQ IV under construction Fred, Even with all the extra weight and redundancy, your avionics are all reliant on a single switch. If that $7 switch goes, your plane is blind, deaf, and dumb! The aeroelectric list does not recommend an avionics buss. This is part of the reason for that. Bill B ------=_NextPart_000_0110_01CC561B.F0BE4990 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

You have a pretty good setup BUT…

I had an avionics master breaker (switch type) in my Bonanza that = failed. What happened was that the housing cracked behind the panel. The = switch failed open on an IFR flight when the housing was no longer able = to hold the contacts together. Your DPST switch can fail in the same way = and will fail open. Both sides will be open from this common mechanical = cause.

My solution was to put in two separate breaker switches in parallel. = I turn only one on at a time. If one fails I can simply turn on the = other.

From:= = Bill Harrelson [mailto:n5zq@verizon.net]
Sent: Sunday, August = 07, 2011 10:57 AM
To: lml@lancaironline.net
Subject: = Re: [LML] Re: Fw: Re: Re-doing my panel - carefully thinking through = failures

Bill,

My = avionics switch is a DPST switch. Basically two switches in one. Each = side controls the power feed from one electrical system. Sure, both = sides of the switch could fail at the same time but that would be = unlikely. On top of that I have a separate, isolated switch that feeds = power only to the GPS/Com so that even if both sides of the avionics = switch should fail or both electrical system 1 and 2 fail, I can power = this unit from system 3. System 3 is an 8 amp B&C generator and an = Odyssey 545 battery.

Bill = Harrelson

N5ZQ 320 = 1,950 hrs

N6ZQ = IV under construction

=

Fr= ed,
Ev= en with all the extra weight and redundancy, your avionics are all = reliant on a single switch. If that $7 switch goes, your plane is = blind, deaf, and dumb! The aeroelectric list does not recommend an = avionics buss. This is part of the reason for that.
Bi= ll B

------=_NextPart_000_0110_01CC561B.F0BE4990--