Return-Path: Received: from [65.33.160.181] (account marv@lancaironline.net) by logan.com (CommuniGate Pro WebUser 4.3c2) with HTTP id 767410 for lml@lancaironline.net; Wed, 02 Mar 2005 18:15:04 -0500 From: "Marvin Kaye" Subject: Re: [LML] Taxiing Matters - Not Taxing, Taxiing! To: lml X-Mailer: CommuniGate Pro WebUser Interface v.4.3c2 Date: Wed, 02 Mar 2005 18:15:04 -0500 Message-ID: In-Reply-To: References: X-Priority: 3 MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit Posted for "Rick Lafford" : Gee Scott, I fly a much slower plane and spend more time taxiing that you. Try flying a Pawnee towing gliders all afternoon. Takes maybe 3 minutes to 2,000' and then back down for the next victim. Ground time typically equalls flight time. Once slowed down and taxiiing, mixture comes back to a visual position that will not allow the engine to achieve much more than a fast idle. The difference in plug fowling and the color of the oil is dramatic, not to mention the reduced fuel burn. We change oil at the 25hr. mark because the engine (O-540) lives a tough life. Without leaning on taxi, the oil actually looks silver. With leaning it's the more typical carbon black. One other difference when leaned is that the engine doesn't develop that typical 540 sycopated idle. Even being able to show these dramatic differences, many old heads, over 75% of our tug drivers and some not all that aged, consider the practice dangerous and subscribe to the Full, Full and Full school of mixture management. Rick Lafford, CFIG Tug Puke and Legacy someday Dansville, NY (DSV) "Touch that mixture knob and you're bound to ruin that engine." """ To me, 15% to 20% makes it really worthwhile to operate the engine properly and, like many others, I aggressively lean during the taxi phase - generally, the big pull to a known visual position of the mixture knob, to be fine tuned when time is available. I do this shortly after engine start and as I pull off the runway after landing (assuming I am able to leave the runway under power). If it matters, the placard on the mixture knob (Push Mixture Rich) has been thumbed to an almost unreadable state. I may have to placard that placard as inoperable. """