Return-Path: Sender: (Marvin Kaye) To: lml Date: Mon, 21 Jul 2003 09:41:23 -0400 Message-ID: X-Original-Return-Path: Received: from imo-r06.mx.aol.com ([152.163.225.102] verified) by logan.com (CommuniGate Pro SMTP 4.1b9) with ESMTP id 2480681 for lml@lancaironline.net; Mon, 21 Jul 2003 09:07:56 -0400 Received: from Sky2high@aol.com by imo-r06.mx.aol.com (mail_out_v36_r1.1.) id q.147.15e3c3a9 (30960) for ; Mon, 21 Jul 2003 09:07:37 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: <147.15e3c3a9.2c4d3f99@aol.com> X-Original-Date: Mon, 21 Jul 2003 09:07:37 EDT Subject: Re: [LML] Re: Essential Bus and other musings X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1058792857" X-Mailer: 9.0 for Windows sub 400 -------------------------------1058792857 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en In a message dated 7/20/2003 11:18:37 PM Central Daylight Time,=20 kycshann@kyol.net writes: My only comment would be that I would think the AP in single pilot operation= =20 would be more of a =E2=80=9Csingle pilots friend=E2=80=9D than the GPS. Any= one? Yep, that is a good idea. After all, the auto pilot (wing level function) i= s=20 my backup for the loss of the vacuum instruments. However, the S-Tec 50 is=20 not a good wing leveler in turbulence so I would say that it also has=20 shortcomings. =20 I also failed to mention that the pitot heat is only present on the main bus= . The reason some of these things are left off the essential bus is because of= =20 the two major failure modes I considered: 1. Alternator/regulator problem. Left with only the battery, I have two=20 choices after pulling the field breaker. Massive load shedding by operating=20= on=20 the essential bus or selective shedding by powering down devices as necessar= y. =20 Even operating on the essential bus, as I approach the landing area, I can=20 determine whether or not to turn on the master to energize the "nice to have= "=20 things. The essential bus gives me many options. 2. Some unspecified catastrophic electrical failure or smoke in the cabin.=20= =20 There probably is a hint as to what caused the problem but chances are that=20= it=20 wasn't one of the items on the essential bus if I keep the number of items=20 on the bus to a minimum. What I would feel comfortable with in such a dire=20 emergency was also a consideration. If I were to look at rewiring the syste= m=20 again, I would seriously consider adding both the auto pilot and pitot heat=20= to=20 the essential bus. Of course, I have to consider the new wire size to the=20 essential bus and the logic of using a diode to isolate the bus.=20 In my case, if the battery failed, I am in serious trouble. This is why a=20 monitoring system is so important. It is also why idiot lights (annunciator= =20 panel) are very useful in pointing out some abnormal condition. The more com= plex=20 in-flight systems either require more intense scanning of displays or some=20 more automatic warning of out-of bounds conditions. In my old Skymaster, I=20= found=20 it incredulous that the vacuum gauge was down by my left knee and out of=20 instrument scan range rather than next to the attitude indicator - by the wa= y,=20 that AI was the very same device that managed the auto pilot.=20 Since I am the manufacturer of my aircraft, I did the risk analysis within=20 the context of the mission and use of said powered lawn dart. I considered=20= the=20 interaction of all the systems to help reduce exposure to single fault=20 catastrophes. I examined redundancy by trying to balance safety and weight,= safety=20 and weight (oops, that's redundant). There are some conditions under which=20= the=20 probability of death are high. It has no air conditioner, no backup engine,= =20 no required copilot, no ice protection, no lightning shield, no totally idio= t=20 proof devices. It can't land on rough fields and it would be courting=20 disaster if the canopy is opened for entry or exit in a driving rain (unlike= a=20 turkey, don't look up). There is no need for a parachute for I have not fig= ured out=20 what unusual attitude is necessary to get the canopy open. All in all, the=20 POH recommends that situations that would expose the design deficiencies=20 outlined above are to be avoided by the reasonable judgment of the pilot. I= f that=20 fails, declare an emergency and do something different than that which got y= ou=20 to the scene of the sin. Scott Krueger 2003 Air Venture Cup Racer #94 Sky2high@aol.com LNC2 N92EX IO320 Aurora, IL (KARR) PS Remember, in a Lancair you can go down or you can slow down, but you can'= t=20 do both. -------------------------------1058792857 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
In a message dated 7/20/2003 11:18:37 PM Central Daylight Time,=20 kycshann@kyol.net writes:

My only comment would be that I would= =20 think the AP in single pilot operation would be more of a =E2=80=9Csingle pi= lots friend =E2=80=9D than the GPS.  Anyone?

 

Yep, that is a good idea.  After all, the auto pilot (wing level=20 function) is my backup for the loss of the vacuum instruments. =20 However, the S-Tec 50 is not a good wing leveler in turbulence so I would sa= y that=20 it also has shortcomings. 
 
I also failed to mention that the pitot heat is only present on the mai= n=20 bus.
 
The reason some of these things are left off the essential bus is=20 because of the two major failure modes I considered:
 
1.  Alternator/regulator problem.  Left with only the battery= ,=20 I have two choices after pulling the field breaker. Massive load shedding by= =20 operating on the essential bus or selective shedding by powering down=20 devices as necessary.  Even operating on the essential bus, as I=20 approach the landing area, I can determine whether or not to turn on the mas= ter to=20 energize the "nice to have" things.  The essential bus gives me many=20 options.
 
2.  Some unspecified catastrophic electrical failure or smoke in=20 the cabin.  There probably is a hint as to what caused the problem but=20 chances are that it wasn't  one of the items on the essential bus if I=20= keep=20 the number of items on the bus to a minimum.  What I would fe= el=20 comfortable with in such a dire emergency was also a consideration.  If= I=20 were to look at rewiring the system again, I would seriously consider adding= =20 both the auto pilot and pitot heat to the essential bus.  Of=20 course, I have to consider the new wire size to the essential bus=20= and=20 the logic of using a diode to isolate the bus. 
 
In my case, if the battery failed, I am in serious trouble.  This=20 is why a monitoring system is so important.  It is also why idiot light= s=20 (annunciator panel) are very useful in pointing out some abnormal=20 condition. The more complex in-flight systems either require more inten= se=20 scanning of displays or some more automatic warning of out-of bounds=20 conditions.  In my old Skymaster, I found it incredulous that the vacuu= m gauge was=20 down by my left knee and out of instrument scan range rather than next=20= to=20 the attitude indicator - by the way, that AI was the very same device=20 that managed the auto pilot. 
 
Since I am the manufacturer of my aircraft, I did the risk analysis=20 within the context of the mission and use of said powered lawn dart.  I= =20 considered the interaction of all the systems to help reduce exposure to sin= gle=20 fault catastrophes.  I examined redundancy by trying to balance safety=20= and=20 weight, safety and weight (oops, that's redundant).  There are some=20 conditions under which the probability of death are high.  It has no ai= r=20 conditioner, no backup engine, no required copilot, no ice protection,=20= no=20 lightning shield, no totally idiot proof devices.  It can't land on rou= gh=20 fields and it would be courting disaster if the canopy is opened for entry o= r exit=20 in a driving rain (unlike a turkey, don't look up).  There is no need=20 for a parachute for I have not figured out what unusual attitude is necessar= y to=20 get the canopy open.  All in all, the POH recommends that situations=20 that would expose the design deficiencies outlined above are to be avoided b= y the=20 reasonable judgment of the pilot.  If that fails, declare an emergency=20 and do something different than that which got you to the scene of the=20 sin.
 
Scott=20 Krueger
2003 Air Venture Cup Racer #94
Sky2high@aol.com
LNC2 N92EX=20= IO320=20 Aurora, IL (KARR)
 
PS Remember, in a Lancair you can go down or you can slow down, bu= t=20 you can't do both.
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