Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Fri, 20 Sep 2002 19:01:19 -0400 Message-ID: X-Original-Return-Path: Received: from mail.viclink.com ([66.129.220.6] verified) by logan.com (CommuniGate Pro SMTP 4.0b8) with ESMTP-TLS id 1740200 for flyrotary@lancaironline.net; Fri, 20 Sep 2002 09:24:36 -0400 Received: from viclink.com (p161.digi00.viclink.com [66.129.192.161]) by mail.viclink.com (8.11.3/8.11.3) with ESMTP id g8KDLZE29038 for ; Fri, 20 Sep 2002 06:21:35 -0700 (PDT) (envelope-from pjmick@viclink.com) X-RAV-AntiVirus: This e-mail has been scanned for viruses on host: mail.viclink.com X-Original-Message-ID: <3D8B207A.1090707@viclink.com> X-Original-Date: Fri, 20 Sep 2002 06:19:54 -0700 From: Perry Mick User-Agent: Mozilla/5.0 (Windows; U; Win95; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: " (Rotary motors in aircraft)" Subject: Re: [FlyRotary] Re: [FlyRotary]Enlarging Trailing spark plug holes References: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit > >> Dr. Michael Seals and myself would recommend that if there is any >> concern about enlarging the trailing spark plug hole, we suggest to have >> a switch that if primary (leading) ignition were to fail you can turn on >> the trailing ignition. >> >> Without enlarging the trailing hole there will likely not be enough >> power to land the vehicle safely. We are troubled with the idea of >> someone using dual ignition on the leading plugs only. If a spark plug >> fouls then there is no TRUE dual ignition. > > > Can't comment on the operating characteristics of the enlarged trailing > sparkplug hole (I haven't flown this configuration) but the last > statement > is totally bogus. > > At around 500 hours, I had an in-flight failure of the leading spark > caused > by the opening of the leading coil ballast resistor. The only > evidence that > this occured was an increase in EGT of about 30 degrees F. I noted this > during an instrument scan but saw no significant loss of power. I > continued > my flight to the scheduled destination about 85 miles away from the point > where the failure occured. > > The leading spark failure was not discovered until the following day > during > preflight checks when I disable both coils (one at a time). The engine > stopped when the trailing coil module was disabled. > > I do use a modified trailing coil ignition timing (same as the leading > timing instead of 15 degrees retarded) which prevents a large loss of > power. > > Tracy Crook > tcrook@rotaryaviation.com > www.rotaryaviation.com > > I can understand the possible blow-by issue on the trailing plug, but what is the mechanism on the leading plug? Seems blow-by could occur there also. -- Perry Mick Duckt N7XR http://www.ductedfan.com