Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Fri, 19 Dec 2003 13:14:50 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m01.mx.aol.com ([64.12.136.4] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2897221 for lml@lancaironline.net; Fri, 19 Dec 2003 10:13:52 -0500 Received: from Sky2high@aol.com by imo-m01.mx.aol.com (mail_out_v36_r4.8.) id q.102.3b2e79a5 (3972) for ; Fri, 19 Dec 2003 10:13:42 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <102.3b2e79a5.2d146fa6@aol.com> X-Original-Date: Fri, 19 Dec 2003 10:13:42 EST Subject: Re: [LML] Further to further to...regarding autopilots. X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1071846822" X-Mailer: Thailand for Windows sub 300 -------------------------------1071846822 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 12/19/2003 8:16:34 AM Central Standard Time, danobrien@cox.net writes: Better to worry about being hit by a car crossing the street. 'Tis true, each year only a few people are hit by a car coming across the road. Virtual flying with modern equipment is fun and safe. Unfortunately, some of us are stuck with ancient technology (circa 1992) during our actual flights. Even with an essential bus, some equipment have only one power wire connected to them. Darn those single point failure modes. It is interesting that a low probability component failure could actually cover up a potentially fatal problem in an unrelated function. In my case, a critical autopilot self-check function (is gyro running?) was spoofed to the "always true" state regardless of the real condition. Be careful of how much you rely on a state of the art device. Take my friend (please) and the Tru-Trak install in his Cozy Mk IV. During an unpowered ground check he found the aileron controls frozen. An early version of the stepper motors had rusted and there was not enough leverage from the short joystick control to override the motor. Tru-Trak has since installed an appropriate shear pin so the control may be freed in the event of some motor jam (newer motors are not likely to rust). Unexpected consequences are the spice of life! Scott Krueger Sky2high@aol.com II-P N92EX IO320 Aurora, IL (KARR) "...as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns - the ones we don't know we don't know." D. Rumsfeld -------------------------------1071846822 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 12/19/2003 8:16:34 AM Central Standard Time,=20 danobrien@cox.net writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 size=3D2>= Better to=20 worry about being hit by a car crossing the=20 street.

'Tis true, each year only a few people are hit by a car coming across t= he=20 road.

Virtual flying with modern equipment is fun and safe. Unfortunate= ly,=20 some of us are stuck with ancient technology (circa 1992) during our ac= tual=20 flights. Even with an essential bus, some equipment have only one= =20 power wire connected to them. Darn those single point failure modes.

It is interesting that a low probability component failure could actual= ly=20 cover up a potentially fatal problem in an unrelated function. In my c= ase,=20 a critical autopilot self-check function (is gyro running?) was spoofed=20 to the "always true" state regardless of the real condition.

Be careful of how much you rely on a state of the art device. = ;=20 Take my friend (please) and the Tru-Trak install in his Cozy Mk IV. Dur= ing=20 an unpowered ground check he found the aileron controls frozen. An ear= ly=20 version of the stepper motors had rusted and there was not enough leverage f= rom=20 the short joystick control to override the motor. Tru-Trak has si= nce=20 installed an appropriate shear pin so the control may be freed in the event=20= of=20 some motor jam (newer motors are not likely to rust).

Unexpected consequences are the spice of life!

=20

Scott=20 Krueger
Sky2high@aol.com
II-P N92EX IO320 Aurora, IL (KARR)

"..= .as=20 we know, there are known knowns; there are things we know we know. We also k= now=20 there are known unknowns; that is to say we know there are some things we do= not=20 know. But there are also unknown unknowns - the ones we don't know we don't=20 know." D. Rumsfeld

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