Return-Path: Sender: (Marvin Kaye) To: lml Date: Sun, 02 Jun 2002 10:23:50 -0400 Message-ID: X-Original-Return-Path: Received: from webterminator28.CRYSTALTECH.COM ([216.119.106.29] verified) by logan.com (CommuniGate Pro SMTP 4.0b1) with ESMTP id 1254064 for lml@lancaironline.net; Sun, 02 Jun 2002 03:02:56 -0400 Received: from primary [12.234.209.102] by webterminator28.CRYSTALTECH.COM (SMTPD32-7.10) id A3209FB0116; Sun, 02 Jun 2002 00:02:56 -0700 X-Original-Message-ID: <003201c20a03$b0a86200$66d1ea0c@attbi.com> From: "Larry Graves" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: Lightning strike X-Original-Date: Sun, 2 Jun 2002 00:04:00 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 The first answer is to incorporate grounding straps while under construction, but for those who have missed this opportunity, we've installed entire ground-strap systems in already-completed Lancair-IVPs and other composite aircraft. The technique involves embedding the braided copper ground straps full-length along the wing trailing-edge cove and tying-in static wicks and other items by running stringers out from the main straps. Aileron wicks are grounded via dedicated strap across the wing-aileron gap. Don't want to encourage current flow through the hinges. Don't know how I'd ground the wing tie-down hard-points on a completed plane if they were surrounded by wet fuel bays. Maybe someone else on the list has done this. I can imagine milling a shallow channel in the lower wing skin over the spar cap from the tie-down to the wing root and floxing in a ground strap, closed out with a scarfed carbon-fiber patch and peel-ply. I'd definitely want to analyze to make sure this did not compromise the torsional strength and stiffness of the wing. Make sure all your sealed cavities are vented. We recently repaired damage to a Lancair-IVP from an airborne lightning strike on the left wingtip. The current passed through a lens cover retaining screw and nutplate, across the interior of the wingtip to another lens retaining screw and out. Screws were each clearly burned, and the clear lens cover was burned/melted at each screw hole. Bigger problem was that a compartment in the wingtip had been closed out but not vented, and the entire trailing edge of the wingtip blew out. It's hard to say if a small vent hole would have prevented the delamination, but there was no vent at all in this case. Oh, and stay clear of thunderstorms... Best Regards, Larry Graves AirCrafters Builder Education & Assistance 140 Aviation Way, Watsonville, CA 95076 Tel: 831-722-9141 Fax: 831-722-9142 www.AirCraftersLLC.com > Larry - > > How would you do this, especially if the wings are closed out? > > Thanks, > > John >