X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 08 Sep 2008 15:31:12 -0400 Message-ID: X-Original-Return-Path: Received: from imo-d06.mx.aol.com ([205.188.157.38] verified) by logan.com (CommuniGate Pro SMTP 5.2.7) with ESMTP id 3119514 for lml@lancaironline.net; Mon, 08 Sep 2008 11:15:55 -0400 Received: from RWolf99@aol.com by imo-d06.mx.aol.com (mail_out_v38_r10.8.) id q.cb4.3f7c164f (34895) for ; Mon, 8 Sep 2008 11:15:46 -0400 (EDT) Received: from smtprly-da02.mx.aol.com (smtprly-da02.mx.aol.com [205.188.249.145]) by cia-da01.mx.aol.com (v121_r2.11) with ESMTP id MAILCIADA014-884f48c541a2236; Mon, 08 Sep 2008 11:15:46 -0400 Received: from webmail-dd20 (webmail-dd20.webmail.aol.com [205.188.104.20]) by smtprly-da02.mx.aol.com (v121_r2.12) with ESMTP id MAILSMTPRLYDA027-5bb848c5419f2e9; Mon, 08 Sep 2008 11:15:43 -0400 X-Original-To: lml@lancaironline.net Subject: Part 23 vs Guaranteed Safety X-Original-Date: Mon, 08 Sep 2008 11:15:43 -0400 X-MB-Message-Source: WebUI X-AOL-IP: 72.19.171.41 X-MB-Message-Type: User MIME-Version: 1.0 From: rwolf99@aol.com Content-Type: multipart/alternative; boundary="--------MB_8CADFDCE581C605_390_E60_webmail-dd20.sysops.aol.com" X-Mailer: AOL Webmail 38575-STANDARD Received: from 72.19.171.41 by webmail-dd20.sysops.aol.com (205.188.104.20) with HTTP (WebMailUI); Mon, 08 Sep 2008 11:15:43 -0400 X-Original-Message-Id: <8CADFDCE57F63A7-390-71F@webmail-dd20.sysops.aol.com> X-Spam-Flag:NO ----------MB_8CADFDCE581C605_390_E60_webmail-dd20.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" Earlier I stated that FAR Part 23 guarantees a certain level of safety.? In retrospect, this may have been somewhat overstated.? But there were some responses that have their genesis in ignorance of the certification process. There is a quantitative process followed by manufacturers whereby they provide an agreed-upon level of safety based on failure probabilities.? The consequences of failures are determined, and depending on how bad it is (minor, major, hazardous, catastrophic) it is allowed to happen with a xx% probability.? The worse the effect of failure, the less likely it is supposed to be. The companies predict the failure probabilities.? These estimates?are only projections.? They are not actually guarantees (and that's where my overstatement occurred).? Does anyone actually believe these projections?? The safety guys do, but I don't.? What I *do* believe, though, is that this methodology has proven to provide a level of safety that stakeholders are comfortable with.? This quantitative process is totally absent in the experimental world.? If it were followed, you'd probably find that most airplanes are just as safe as the certifed ones in many areas, safer in rare instances, and worse in other areas.? But blanket statements like "all homebuilts are safer than certified airplanes" and "the certification process adds no safety -- it is purely bureaucratic BS" are based in ignorance. And no, I don't suggest that the FAA mandate that this process be followed by amateurs (as in "amateur-built" -- people like you and me).? - Rob Wolf ----------MB_8CADFDCE581C605_390_E60_webmail-dd20.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii" Earlier I stated that FAR Part 23 guarantees a certain level of safety.  In retrospect, this may have been somewhat overstated.  But there were some responses that have their genesis in ignorance of the certification process.

There is a quantitative process followed by manufacturers whereby they provide an agreed-upon level of safety based on failure probabilities.  The consequences of failures are determined, and depending on how bad it is (minor, major, hazardous, catastrophic) it is allowed to happen with a xx% probability.  The worse the effect of failure, the less likely it is supposed to be.

The companies predict the failure probabilities.  These estimates are only projections.  They are not actually guarantees (and that's where my overstatement occurred).  Does anyone actually believe these projections?  The safety guys do, but I don't.  What I *do* believe, though, is that this methodology has proven to provide a level of safety that stakeholders are comfortable with. 

This quantitative process is totally absent in the experimental world.  If it were followed, you'd probably find that most airplanes are just as safe as the certifed ones in many areas, safer in rare instances, and worse in other areas.  But blanket statements like "all homebuilts are safer than certified airplanes" and "the certification process adds no safety -- it is purely bureaucratic BS" are based in ignorance.

And no, I don't suggest that the FAA mandate that this process be followed by amateurs (as in "amateur-built" -- people like you and me). 

- Rob Wolf
----------MB_8CADFDCE581C605_390_E60_webmail-dd20.sysops.aol.com--