X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 20 Dec 2009 02:36:31 -0500 Message-ID: X-Original-Return-Path: Received: from imr-da01.mx.aol.com ([205.188.105.143] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with ESMTP id 4027654 for lml@lancaironline.net; Fri, 18 Dec 2009 10:54:15 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.143; envelope-from=Sky2high@aol.com Received: from imo-ma02.mx.aol.com (imo-ma02.mx.aol.com [64.12.78.137]) by imr-da01.mx.aol.com (8.14.1/8.14.1) with ESMTP id nBIFrddY004973 for ; Fri, 18 Dec 2009 10:53:39 -0500 Received: from Sky2high@aol.com by imo-ma02.mx.aol.com (mail_out_v42.5.) id q.ce2.59e846ba (29672) for ; Fri, 18 Dec 2009 10:53:29 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Fri, 18 Dec 2009 10:54:43 EST Subject: Re: [LML] Firewall X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1261151683" X-Mailer: AOL 9.5 sub 155 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com -------------------------------1261151683 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en Steve, =20 I have raised this issue before - Generally, all fast non-pressurized =20 aircraft have lower than ambient pressure in the cabin. Generally, the= cowl=20 outside the cooling plenum has a pressure slightly higher than ambient.= Any=20 opening in the firewall allows cowl atmosphere to enter the cabin. Make= =20 sure any firewall pass-throughs are sealed as best as they can be. Remem= ber=20 that burned-through cowl-located heater SCAT hose will also allow fire=20 products to enter the cabin. =20 A side note: The drain hole in the belly under the center console drew= =20 exhaust into the cockpit. I found this when I installed a digital CO =20 monitor. The hole is now plugged. =20 Scott Krueger AKA Grayhawk =20 =20 =20 In a message dated 12/18/2009 9:19:59 A.M. Central Standard Time, =20 mcmess1919@yahoo.com writes: =20 Years ago Van=E2=80=99s tested several factory built RV=E2=80=99s for smo= ke penetration=20 of the firewall. I remember they were amazed how much smoke they got thr= u=20 what they thought were pretty tight electrical, cable and misc. fittings= in=20 a ground simulation. They tightened up the obvious holes and used High= =20 Temp Silicone and still had an unacceptable volume of smoke coming in. = =20 Fire or even an oil leak might have smoke that could prevent breathing=20 long enough or obscure vision or be enough of a distraction (pick one or= more)=20 to set up a fatal scenario. This could have been a factor in the=20 Watsonville crash. =20 Steve Colwell Legacy =20 -------------------------------1261151683 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en

Steve,

I have raised this issue before - Generally, all fast non-pressurized= =20 aircraft have lower than ambient pressure in the cabin. General= ly,=20 the cowl outside the cooling plenum has a pressure slightly higher than=20 ambient. Any opening in the firewall allows cowl atmosphere to enter= the=20 cabin. Make sure any firewall pass-throughs are sealed as= best=20 as they can be. Remember that burned-through cowl-located= heater=20 SCAT hose will also allow fire products to enter the cabin.

A side note: The drain hole in the belly under the center conso= le=20 drew exhaust into the cockpit. I found this when I installed a digit= al CO=20 monitor. The hole is now plugged.

Scott Krueger AKA Grayhawk

In a message dated 12/18/2009 9:19:59 A.M. Central Standard Time,=20 mcmess1919@yahoo.com writes:

Years=20 ago Van=E2=80=99s tested several factory built RV=E2=80=99s for smoke pe= netration of the=20 firewall. I remember they were amazed how much smoke they got thru= what=20 they thought were pretty tight electrical, cable and misc. fittings in= a=20 ground simulation. They tightened up the obvious holes and used Hi= gh=20 Temp Silicone and still had an unacceptable volume of smoke coming in.&n= bsp;=20

Fire=20 or even an oil leak might have smoke that could prevent breathing long= enough=20 or obscure vision or be enough of a distraction (pick one or more) to se= t up a=20 fatal scenario. This could have been a factor in the Watsonville= crash.=20

Steve=20 Colwell Legacy

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