X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from tomcat.al.noaa.gov ([140.172.240.2] verified) by logan.com (CommuniGate Pro SMTP 4.3.2) with ESMTP id 962941 for flyrotary@lancaironline.net; Wed, 25 May 2005 11:09:43 -0400 Received-SPF: none receiver=logan.com; client-ip=140.172.240.2; envelope-from=bdube@al.noaa.gov Received: from mungo.al.noaa.gov (mungo.al.noaa.gov [140.172.241.126]) by tomcat.al.noaa.gov (8.12.11/8.12.0) with ESMTP id j4PF8xW5006134 for ; Wed, 25 May 2005 09:09:00 -0600 (MDT) Message-Id: <6.2.1.2.0.20050525083207.01d94c40@mailsrvr.al.noaa.gov> X-Mailer: QUALCOMM Windows Eudora Version 6.2.1.2 Date: Wed, 25 May 2005 08:52:18 -0600 To: "Rotary motors in aircraft" From: Bill Dube Subject: Galvanic action (was: radiators as jugs 4) In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed The main problem I see is that the radiators are not electrically isolated from the aircraft frame and engine block. There is no vibration isolation either. This can cause serious problems with metal fatigue and with corrosion driven by galvanic action. The vibration from the engine will fatigue the fins and tubes and perhaps the inlets. The electrical connection between the radiator and the engine block competes the circuit on a galvanic "cell". The dissimilar metals of the engine block (cast iron and/or aluminum) and the radiator (copper or aluminum) along with the water acting as the electrolyte form a very effective battery (cell, actually). The current flows in the circuit and eats the crap out of the radiator. I would see this problem often when I was a car mechanic (previous life). Folks would remove the radiator, and then replace it without the rubber grommets. About a year later the radiator would become Swiss cheese. Similar things happen to household water heaters that are improperly installed. Bill Dube'