---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 11/14/23: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:56 AM - Re: Re: AeroElectric-List Digest: 1 Msgs - 11/11/23 (Robert L. Nuckolls, III) 2. 08:59 AM - Re: Fuse Upstream of Breaker (Robert L. Nuckolls, III) 3. 09:30 AM - Re: Fuse Upstream of Breaker (Robert L. Nuckolls, III) 4. 01:09 PM - Re: Fuse Upstream of Breaker (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 08:56:45 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: AeroElectric-List Digest: 1 Msgs - 11/11/23 At 09:05 PM 11/12/2023, you wrote: >Different topic:=C2 Are Lithium ion batteries >affected by low ambient temperature like, or any >where close to, what lead acid batteries suffer down around zero F and below? >. . . Just wondering if electric powered cars >and trucks will be seriously affected this winter up north. Performance of every battery technology is influenced by temperature of its chemistry. Here is one of many resources on the topic: https://batteryfinds.com/what-do-you-think-of-lifepo4-temperature-range/ Bob . . . //// (o o) ===========o00o=(_)=o00o======= = < Go ahead, make my day . . . > < show me where I'm wrong. > ======================== ======== In the interest of creative evolution of the-best-we-know-how-to-do based on physics and good practice. ________________________________ Message 2 _____________________________________ Time: 08:59:57 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Fuse Upstream of Breaker At 11:49 AM 11/13/2023, you wrote: >Listers, > >I want to put a 5 amp breaker in the regulator circuit in a airplane >that has a 12-fuse distribution panel. The breaker would be mounted >in the instrument panel which is about 2-3 feet away from the fuse panel. Per Charlie's suggestion and configurations depicted in ALL the Z-figures, fusible linked extension of the bus to the remote breaker is recommended. Bob . . . //// (o o) ===========o00o=(_)=o00o======== < Go ahead, make my day . . . > < show me where I'm wrong. > ================================ In the interest of creative evolution of the-best-we-know-how-to-do based on physics and good practice. ________________________________ Message 3 _____________________________________ Time: 09:30:30 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Fuse Upstream of Breaker > >I am looking at BobN's analysis of a fatal accident in a >Experimental with an electrically-dependent engine where the >electrical system had fuses up-stream/in-series with breakers. (PDF attached) > >IIRC, the system suffered a ground fault in one of the ignition >modules which was supposed to be protected by a 5A circuit >breaker. The breaker is down-stream from 2 fuses. The failure >occurred because BOTH up-stream fuses blew before the 5A breaker. I >don't know what the values of the up-stream fuses were. This was not a fatal accident although very expensive with some victims suffering enduring effects of their injuries. Suggest you study the analysis of that accident more carefully. Deliverables produced for my client in this analysis are available at: http://aeroelectric.com/Reference_Docs/Accidents/N811HB_Feb2008_LA-IVp/ In particular, check out the demonstrated performance of the system AS INSTALLED on the aircraft: http://aeroelectric.com/Reference_Docs/Accidents/N811HB_Feb2008_LA-IVp/02_N811HB_Configuration.mp4 This project was burdened with many 'slices of swiss cheese', errors in judgement that set the stage for this accident. The most significant features of this system were: (1) Bus tie contactor featured in Z-14 was replaced with a DIODE and breaker. The diode injected a fixed voltage drop between main and aux busses of approximately 0.7 volts. (2) For reasons not clear to me, it was deemed useful to bring power sources for BOTH flight critical systems TOGETHER into a single point of failure. (3) Lack of failure mode effects analysis supported by LOADS data for the ignition system. The diode voltage drop and mis-configuration of the ignition power feeders caused a single fuse to be burdened with the draw for BOTH ignition systems. This combined with the fact that max draw was transient . . . take off and initial climb-out with prop set for full increase. These events were only once-per flight cycle and limited to perhaps 60 seconds per event. Not severe enough to pop the fuse on any one event but EACH event abused the fuse causing its I(squared)T fusing value to steadily erode. The main fuse went first leaving the aux fuse to soldier on for some number of flight cycles but it too eventually succumbed to the abuse. There was no gross fault condition causing the fuses to open; rather a combination of design decisions which produced a system that WAS GOING TO FAIL. Had the system been configured in the spirit and intent of Z-14 as published, http://aeroelectric.com/Reference_Docs/Accidents/N811HB_Feb2008_LA-IVp/04_Z14_Hypothesis.mp4 those ignition breakers and common, dual-feed ignition bus would NOT have been installed and just perhaps, that airplane and those people would still be whole today. I'll never forget my first view of the sketches for the system as-installed on HB811. My client spread them out on his desk and I could see immediately why this engine quit on 'short final to the rocks'. Bob . . . //// (o o) ===========o00o=(_)=o00o======== < Go ahead, make my day . . . > < show me where I'm wrong. > ================================ In the interest of creative evolution of the-best-we-know-how-to-do based on physics and good practice. ________________________________ Message 4 _____________________________________ Time: 01:09:36 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Fuse Upstream of Breaker > The main fuse went first leaving the aux fuse > to soldier on for some number of flight cycles > but it too eventually succumbed to the > abuse. This is what FMEA is all about. Here was an opportunity for a latent failure to go un-annunciated and impossible to detect in a pre-flight procedure. Interestingly also, even if the fuses had been fitted with LED indicators, it is unlikely that the failed fuse would have 'indicated' anything. Voltage across open fuse too low. Bob . . . //// (o o) ===========o00o=(_)=o00o======== < Go ahead, make my day . . . > < show me where I'm wrong. > ================================ In the interest of creative evolution of the-best-we-know-how-to-do based on physics and good practice. ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.