X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao12.cox.net ([68.230.241.27] verified) by logan.com (CommuniGate Pro SMTP 5.0.3) with ESMTP id 862852 for flyrotary@lancaironline.net; Sun, 04 Dec 2005 11:48:00 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.27; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao12.cox.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20051204164536.IWHZ17437.fed1rmmtao12.cox.net@BigAl> for ; Sun, 4 Dec 2005 11:45:36 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Intersting flight Date: Sun, 4 Dec 2005 08:47:18 -0800 Message-ID: <000001c5f8f2$63653b80$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C5F8AF.5541FB80" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C5F8AF.5541FB80 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable You make an excellent point on the single failure point. I've been trying to come up with a way to eliminate the problem, but outside of going to 2 switches, I'm not sure how to do it. Even with 2 switches the one for the engine is still a single failure point for the engine. =20 =20 I'm sure there is more than one 'right' way. My choice was 2 batteries, = two contactors, 2 'master' switches. The engine critical bus is powered directly from both batteries, isolated by Schottky diodes. The circuits = for each set of injectors, and each set of coils are separate, as is backup = for ECU and fuel pumps. These circuits are protected by fuses. Both = masters can be off and the engine still run. =20 Your experience caused me to review my system for single point weakness. = The 2 master switches have separate grounds to the panel ground bus. There = is only one #12 lead from the panel ground bus back to the copper pipe = (which is my main ground lead from batteries in front to engine in back). It = is bolted and soldered at the ground bus, but fastened to the copper pipe = with a sheet metal screw through a loop connector. I need to review that connection to make certain that it can not come loose or lose contact. = I will also review the other single point connections on the ground side. = I don't consider a heavy gauge wire a potential single point failure; but = a connection always has to be considered suspect. =20 Sharing your experience can result in improved reliability for the rest = us. In my business as commodity trader I have a motto; "take the loss, but = don't lose the lesson". Each time there is an occurrence such as yours, we = need to learn from it. =20 Best, =20 Al =20 =20 =20 =20 ------=_NextPart_000_0001_01C5F8AF.5541FB80 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

You make an excellent point on the single failure

point.  I've been trying to come up with a way to

eliminate the problem, but outside of going to 2

switches, I'm not sure how to do it. Even with 2

switches the one for the engine is still a single

failure point for the engine. 

 

I’m = sure there is more than one ‘right’ way.  My choice was 2 = batteries, two contactors, 2 ‘master’ switches.  The engine critical = bus is powered directly from both batteries, isolated by Schottky diodes.  = The circuits for each set of injectors, and each set of coils are separate, = as is backup for ECU and fuel pumps.  These circuits are protected by = fuses.  Both masters can be off and the engine still run.

 <= /font>

Your = experience caused me to review my system for single point weakness. The 2 master switches = have separate grounds to the panel ground bus. There is only one #12 lead = from the panel ground bus back to the copper pipe (which is my main ground lead = from batteries in front to engine in back).  It is bolted and soldered at the = ground bus, but fastened to the copper pipe with a sheet metal screw through a loop connector.  I need to review that connection to make certain that = it can not come loose or lose contact.  I will also review the other = single point connections on the ground side.  I don’t consider a heavy = gauge wire a potential single point failure; but a connection always has to be = considered suspect.

 <= /font>

Sharing your experience can result in improved reliability for the rest us.  In = my business as commodity trader I have a motto; “take the loss, but = don’t lose the lesson”.  Each time there is an occurrence such as = yours, we need to learn from it.

 <= /font>

Best,

 <= /font>

Al

 <= /font>

 <= /font>

 <= /font>

 <= /font>

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