Return-Path: Sender: (Marvin Kaye) To: lml Date: Sun, 20 Jul 2003 19:08:03 -0400 Message-ID: X-Original-Return-Path: Received: from imo-r08.mx.aol.com ([152.163.225.104] verified) by logan.com (CommuniGate Pro SMTP 4.1b9) with ESMTP id 2480156 for lml@lancaironline.net; Sun, 20 Jul 2003 17:07:55 -0400 Received: from RWolf99@aol.com by imo-r08.mx.aol.com (mail_out_v36_r1.1.) id q.f9.2f73d93a (4446) for ; Sun, 20 Jul 2003 17:07:53 -0400 (EDT) From: RWolf99@aol.com X-Original-Message-ID: X-Original-Date: Sun, 20 Jul 2003 17:07:53 EDT Subject: Essential Busses X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en X-Mailer: AOL 5.0 for Windows sub 108 Shannon (who is spearheading a very informative discussion -- thanks!) state= s=20 the following about his essential bus which I find rather surprising.... <> and then <<(ie flaps, lights, hyd pump which would seem to have this=20 resistive failure mode, but wouldn=E2=80=99t reside on the Ess bus)>> I'm curious as to why an EFIS, a Garmin 430, a backup attitude indicator, an= d=20 autopilot and a transponder would all be on an essential bus! Second, why=20 wouldn't the landing gear be on there? OK, it's clear that Shannon is using his essential bus as a simple (one=20 switch?) means of load shedding rather than a true "emergency" bus. And tha= t's=20 fine. The architecture he suggests gives as much power supply reliability i= n=20 this backup mode as an average spam can has in it's primary mode. (In fact,= =20 that's the whole point he's trying to make.) The only remaining issues are=20 whether or not anything else is also broken and this is why Jeff and Hamid a= re=20 throwing darts -- with Hamid's being a little less sharp and pointy. Perso= nally,=20 I'm looking forward to another round on this topic in hopes of learning even= =20 more than I have already. However, if this were truly an "emergency" bus I would submit that you don't= =20 need an autopilot, an EFIS or even a transponder. Hell, I'd rather have the= =20 landing gear than a transponder -- the transponder may keep ATC's blood=20 pressure down but I'd be more worried about my own. At work (Aviation Technology Group -- we're working on the Javelin jet which= =20 will be FAR Part 23 certified) we're arguing about these very issues this=20 month. We have to live by FAR requirements which basically require a 30 min= ute=20 "aviate, navigate, communicate" capability in the event of a generator failu= re. =20 However, we are also interested in an above-and-beyond requirement which=20 allows us to shut down all of the electrons in the aircraft in the event of=20= an=20 electrical system fire. We would then operate on a separate mini-battery=20 powering a standby attitude indicator ONLY. This allows up to keep the "can= opy side=20 up" if this happens in IFR. (The FAR's only require that you be able to=20 operate VFR after an electrical fire.) Each of our two PFD's would operate=20= on=20 separate battery busses and we'd hope to be able to revive one of the busses= =20 without the fire restarting. With one PFD operating we get "navigate, commu= nicate"=20 function restored. We haven't come to any final decisions yet but you can=20 imagine why I find this entire thread so interesting. (Actually the Dynon E= FIS=20 would be perfect for this appliaction if it were certified....) - Rob Wolf LNC2 51% Javelin 0%