X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao11.cox.net ([68.230.241.28] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 988437 for flyrotary@lancaironline.net; Thu, 16 Feb 2006 22:33:15 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.28; envelope-from=dale.r@cox.net Received: from [192.168.1.103] (really [68.2.139.17]) by fed1rmmtao11.cox.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20060217033059.HKTN6244.fed1rmmtao11.cox.net@[192.168.1.103]> for ; Thu, 16 Feb 2006 22:30:59 -0500 Message-ID: <43F543D6.8050005@cox.net> Date: Thu, 16 Feb 2006 20:32:38 -0700 From: Dale Rogers User-Agent: Mozilla Thunderbird 1.0.6 (Windows/20050716) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Iron Plates OK - ?? References: In-Reply-To: Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit David Leonard wrote:

So just for fun, I took a piece of scotch brite to the "discolored surface" of my side housings (the ones that overheated). I guess it was just a carbon coating because it came off in less than a minute of light rubbing. Here are the before and after shots. No evidence of cracks or distortion, so I plan to use them in my re-build.

Dave, You might want to have them magnafluxed, just to be safe. As I mentioned before, it takes about 600 degrees F to turn steel blue. However, the blue is a surface discoloration - actually a form of oxidation - thus it will come off with scotchbrite the same a rust. The different colors that the metal turns as it heats up (straw, purple, blue) are due to different oxides that form at the various temperatures. The blue may be gone, but the underlying metal has still been at 600* while the rest of the iron has not. Dale R. COZY MkIV #1254