---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 07/30/21: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:56 AM - Re: Re: faston failures et. als. (Steve Kelly) 2. 08:04 AM - Re: Melted battery contractor ground wire (morsegarrett) ________________________________ Message 1 _____________________________________ Time: 04:56:55 AM PST US From: Steve Kelly Subject: Re: AeroElectric-List: re: faston failures et. als. Bob, Thanks for you're thoughts on this. The picture of the darkened terminal was exactly what mine looked like. My strobes are on every flight. About 300 hours now. Something I will be watching. One question though. What might total failure look like? Blown fuse? Smoke? Steve On Thu, Jul 29, 2021 at 8:06 PM Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > At 10:02 AM 7/27/2021, you wrote: > > The issue of female "fast on" connectors losing their grip and creating a > high resistance point is generally related to the quality of the connectors > used. The connectors sold at the local auto parts stores are of inferior > quality and often cause this sort of issue. Best to use the PIDG connectors > that Bob N. recommends. > > > We've had several incidents of strobe switch failures > over the years. Had a builder report serial > failures on his airplane that took some time and > head scratching to figure out. This was probably > 20 years ago. > > http://aeroelectric.com/Pictures/Switches/Carling_Cutaway.jpg > > > http://aeroelectric.com/Pictures/Switches/Toggle_Switch_with_Fast-On_Tabs.jpg > > If you study the images above you can plot the > pathway for current flow through the switch. Note > that there are 10 'ohmic' joints in (metal-to-metal) > the wire-to-wire pathway. There are 11 conductive > components that carry current to, through and > away from the switch. > > Two of those joints are moving . . . saddle pivot > and contact interface. All the rest are non-moving > wherein various fabrication processes strive for > gas-tight, low resistance joining. > > Loss of function for this assembly can have beginnings > at any one or combination of failures in the ohmic > joints. Degradation of a joint manifests in an > increase of resistance between the two components. > > Increased resistance is followed by HEATING . . . just > a few degrees at first . . . but it's regenerative. > Heating exacerbates loss of conduction causing > increased heating which accelerates lost of conduction. > > It's never a rapid process . . . it may take many > hours of operation to bring the whole thing down > to failure. Impending failures are often caught > visually . . . note the discoloration of the terminal > insulator here: > > http://aeroelectric.com/Pictures/Switches/VL_Switch_Failure_2.jpg > > This image suggests loss of integrity in the terminal- > to-wire crimp. Overt failure may still be months > off after hours of operation. > > Modern flash tube strobe systems are particularly > prone to failures of this kind. Several compounding > reasons. (1) strobes are often operated for duration > of flight from engine start up to shut down. (2) The > flash tube strobe system is probably the most demanding > on the panel switch due to current draw . . . a draw > that is HIGHEST at low bus voltages when the modern, > constant power high voltage circuits INCREASE drain > to maintain performance. > > We've studied several switch failure cases here on > the List over the years. EVERY failure began with localized > heating as a consequence of degraded conduction in ONE > joint. It was not uncommon for heating to degrade surrounding > materials to the point where multiple joints began to > participate in total failure of the switch. > > Failure science is an interesting study in material > characteristics and physics. Without a well considered > study of evidence, it's easy to blame the quality of > a component but one needs to be mindful of the > general nature of failures. They generally have > a single point of origin that can cascade into > multiple events ending in total failure. > > > Bob . . . > > Un impeachable logic: George Carlin asked, "If black boxes > survive crashes, why don't they make the whole airplane > out of that stuff?" > ________________________________ Message 2 _____________________________________ Time: 08:04:21 AM PST US Subject: AeroElectric-List: Re: Melted battery contractor ground wire From: "morsegarrett" I think this is not unusual. You don't have to worry too much to it fireboy and watergirl (https://fireboyandwatergirl.onl) Read this topic online here: http://forums.matronics.com/viewtopic.php?p=502841#502841 ------------------------------------------------------------------------------------- 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.