X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 09 Jul 2007 21:02:57 -0400 Message-ID: X-Original-Return-Path: Received: from global.delionsden.com ([66.150.29.112] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTPS id 2167450 for lml@lancaironline.net; Mon, 09 Jul 2007 14:47:48 -0400 Received-SPF: none receiver=logan.com; client-ip=66.150.29.112; envelope-from=n103md@yahoo.com Received: from bmackey by global.delionsden.com with local (Exim 4.62) (envelope-from ) id 1I7yGI-0001fA-RI for lml@lancaironline.net; Mon, 09 Jul 2007 14:47:06 -0400 Received: from 12.146.139.19 ([12.146.139.19]) (SquirrelMail authenticated user bmackey) by www.bmackey.com with HTTP; Mon, 9 Jul 2007 11:47:06 -0700 (PDT) X-Original-Message-ID: <13213.12.146.139.19.1184006826.squirrel@www.bmackey.com> X-Original-Date: Mon, 9 Jul 2007 11:47:06 -0700 (PDT) Subject: RE: [LML] Flap Switch From: "bob mackey" X-Original-To: lml@lancaironline.net User-Agent: SquirrelMail/1.4.9a MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - global.delionsden.com X-AntiAbuse: Original Domain - lancaironline.net X-AntiAbuse: Originator/Caller UID/GID - [32015 2012] / [47 12] X-AntiAbuse: Sender Address Domain - yahoo.com X-Source: X-Source-Args: X-Source-Dir: Bob Belshe asks: > While we are talking about flap relays, why do you think the Lancair > manual design uses the second (redundant) pole on the flap switch? In the standard system, failure of a limit switch or relay in the closed position will cause the motor to overrun. Having the power to the motor also switched gives a second way to interrupt the current to the motor. That also provides some protection against an allen wrench dropped into the armrest panel where it might accidentally short out a relay contact. > Personally, I don't see any advantage to going to a solid-state > relay system. With diode snubbers, the original relays seem to be > pretty reliable. Do you mean thousand-hour MTBF reliable, ten-thousand hours? Certainly the diode snubbers will reduce contact arcing. But a properly-designed and installed solid-state switch will outlast a properly-designed and installed relay. That said, I have not chosen to retrofit my airframe. I still have relays, and plenty of other fish to fry.... like nylaflow brake lines and tiny slow leaks on all the 19 year-old hydraulic cylinders.