Return-Path: Received: from [65.33.166.167] (account ) by logan.com (CommuniGate Pro WebUser 4.0b7) with HTTP id 1737885 for ; Fri, 20 Sep 2002 00:28:54 -0400 From: "Marvin Kaye" Subject: Re: [FlyRotary]Enlarging Trailing spark plug holes To: flyrotary X-Mailer: CommuniGate Pro Web Mailer v.4.0b7 Date: Fri, 20 Sep 2002 00:28:54 -0400 Message-ID: In-Reply-To: <002001c26057$4f96cf60$284ffea9@suwanneevalley.net> MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit Posted for "Tracy Crook" : > 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