X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nm9-vm0.bullet.mail.sp2.yahoo.com ([98.139.91.196] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with SMTP id 5436804 for flyrotary@lancaironline.net; Sat, 10 Mar 2012 20:28:23 -0500 Received-SPF: none receiver=logan.com; client-ip=98.139.91.196; envelope-from=echristley@att.net Received: from [98.139.91.62] by nm9.bullet.mail.sp2.yahoo.com with NNFMP; 11 Mar 2012 01:27:48 -0000 Received: from [68.142.200.227] by tm2.bullet.mail.sp2.yahoo.com with NNFMP; 11 Mar 2012 01:26:48 -0000 Received: from [66.94.237.116] by t8.bullet.mud.yahoo.com with NNFMP; 11 Mar 2012 01:26:48 -0000 Received: from [127.0.0.1] by omp1021.access.mail.mud.yahoo.com with NNFMP; 11 Mar 2012 01:26:48 -0000 X-Yahoo-Newman-Id: 225884.61126.bm@omp1021.access.mail.mud.yahoo.com Received: (qmail 11179 invoked from network); 11 Mar 2012 01:26:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1331429208; bh=uVuGxwvNc62YFA2I1Uq5n7u368904iP+OByKghuMui8=; h=X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:Date:From:Reply-To:User-Agent:MIME-Version:To:Subject:References:In-Reply-To:Content-Type; b=jEb0Azs0Nblz1CaZIwurOAsOiRyxm2THY1XiOMuUGnP4CLjhnJAzrB4ZSah1scBQ1DLKNqfhTsmsjObtlQLNCHUa47/MzdEd5lOQb/V9RNugKtLdTxZj0sY53dbpYnJKamy+sE88TdcvC1IQfPX8KYo6+Wir5Thnp4PRWu6nSas= X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: E_xl9yUVM1kpaj.nLdzRg183Sbit8HiFJQfzhcgi9QJghbq 0m9OSHhWZoTJpCttMfp3baFqF584bX3rZKyGg6Og3UfLTa1TwraA9CZz7i9. ko5Xi5XMU54hxCi3mBAVG0SSWJ_GawPnPEVTS92bAsupgbJnPgCiWKOk28aX GodyXD4Jld6k7j4PAQUu85B7Bem.sGN8bLDNQkbGDNJbHiYPA3r_zjnYjlCA NlIFqW1pDm1_txUyPlbEiM0Dw9y709ASasa81RCQnuulhd9DeUlpUPD6SUtF v..3ldExkI1qbd9Hb0ZAhysB6VefUgYZ_x81NQ3aVVV8u8zzvz1c36zOqjDw 7mKZYwM9NCtFw0BOTgfYBaUEJ1MADbM6s9oVf.Yc_VGvQETlZqgZykWG1tDI tRA-- X-Yahoo-SMTP: 40RP3pGswBDvPav1a.I8eMv.KS8bdgWBnCloVoKaow-- Received: from [192.168.1.2] (echristley@65.190.51.71 with plain) by smtp108.sbc.mail.mud.yahoo.com with SMTP; 10 Mar 2012 17:26:47 -0800 PST Message-ID: <4F5BFF36.5030201@att.net> Date: Sat, 10 Mar 2012 20:26:14 -0500 From: Ernest Christley Reply-To: echristley@att.net User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110921 Lightning/1.0b2 Thunderbird/3.1.15 MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Failure of an LS-1 D-580 type ignition coil References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------000309040603040904020602" This is a multi-part message in MIME format. --------------000309040603040904020602 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 03/09/2012 11:22 PM, DLOMHEIM@aol.com wrote: > Tracy wrote: >As usual, the in-flight symptom was a rise in EGT on the > affected rotor. > Can someone describe the science behind a "rise in EGT" when we lose a > single coil. I would have expected a drop in EGT due to less thorough > burning of the mixture and therefore excess un-burnt fuel which I > thought would provide cooler temps of the exhaust stream as it passes > the EGT probe. > Must be missing something very basic here... > Thanks for any clarity! :) > Doug Lomheim > RV-9A / 13B FWF I think the missing piece is that when running rich of peak to cool the exhaust, the mixture leaves the chamber without any oxygen remaining and with the burn therefore complete. When a coil dies, there's still some oxygen left, so the mixture is still burning as it enters the exhaust. --------------000309040603040904020602 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit On 03/09/2012 11:22 PM, DLOMHEIM@aol.com wrote:

Tracy wrote: >As usual, the in-flight symptom was a rise in EGT on the affected rotor.

Can someone describe the science behind a "rise in EGT" when we lose a single coil. I would have expected a drop in EGT due to less thorough burning of the mixture and therefore excess un-burnt fuel which I thought would provide cooler temps of the exhaust stream as it passes the EGT probe.

Must be missing something very basic here...

Thanks for any clarity! :)

Doug Lomheim

RV-9A / 13B FWF

I think the missing piece is that when running rich of peak to cool the exhaust, the mixture leaves the chamber without any oxygen remaining and with the burn therefore complete. When a coil dies, there's still some oxygen left, so the mixture is still burning as it enters the exhaust.
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