---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 11/03/13: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:10 AM - CONTACT EXTRACTOR (racerjerry) 2. 12:43 PM - Re: Contactors (Peter Pengilly) 3. 02:08 PM - Re: Contactors (Sacha) 4. 11:28 PM - Re: Contactors (Etienne Phillips) ________________________________ Message 1 _____________________________________ Time: 08:10:29 AM PST US Subject: AeroElectric-List: CONTACT EXTRACTOR From: "racerjerry" Can someone give me the (working tip end) dimensions of the Bendix/King contact extraction tool p/n 047-05099-001 that is used to remove contacts p/n 030-01107-00xx as used on KT 76 and KX 155. Please no guesses I need a caliper on this one. I will be working under extremely difficult conditions. Apparently, this tool is also known as Molex p/n HT-1884 Thank you for your help. -------- Jerry King Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411998#411998 ________________________________ Message 2 _____________________________________ Time: 12:43:27 PM PST US From: Peter Pengilly Subject: Re: AeroElectric-List: Contactors Sacha, Apologies, I'm not very familiar with Rotax components. It would be good to know how much current a Rotax starter pulls - I guess it is likely that as the engine is only 1200cc the draw would rather less than a starter for a 5/6 litre Lyc. I believe a Lyc starter pulls between 200 to 500A depending on starter type and compression ratio. If a Rotax pulls substantially less the potential for the starter contactor to weld itself shut would be lower (probably not a linear relationship), and so the risk of a problem that much lower. You may decide you can tolerate the risk without additional mitigations. Peter On 02/11/2013 21:10, Sacha wrote: > > >>> If a modern starter with a piggy-back solenoid is fitted, >>> to avoid the master relay handling the starting current, the jumper that >>> normally energises the solenoid can be brought into a cockpit switch to >>> disable the starter if the the starter contactor does weld on. A small >>> additional parts count, but the switch never does any switching except in >>> emergency. >> You're speaking about the solenoid on the starter motor? I don't recall >> seeing any external jumper there (the engine is a Rotax 912). I'll have a >> check next time I'm down at the hangar. > I couldn't find anything there unfortunately. The starter motor just has one terminal for the fat positive wire. > > ________________________________ Message 3 _____________________________________ Time: 02:08:44 PM PST US Subject: Re: AeroElectric-List: Contactors From: Sacha Thanks Peter Actually I realized today that I can easily use the semi-useless alternator off warning light that I fitted on my panel as a "starter on warning light" with minimal rewiring. Since 99.9% of the time I'm going to be on the ground while starting my engine, I think I can live with the fact of not being able to disable the starter motor if the contactor gets stuck somehow since I can just shut down the engine. Out of interest I will try to measure how many amps are drawn by the starter next time I'm down at the hangar. Though I suspect this would vary somewhat depending on temperature. I've almost finished the CAD drawings of my electrical system so I'll be submitting them to the list for review and criticism soon. Sacha On Nov 3, 2013, at 21:42, Peter Pengilly wrote: > Apologies, I'm not very familiar with Rotax components. It would be good to know how much current a Rotax starter pulls - I guess it is likely that as the engine is only 1200cc the draw would rather less than a starter for a 5/6 litre Lyc. I believe a Lyc starter pulls between 200 to 500A depending on starter type and compression ratio. If a Rotax pulls substantially less the potential for the starter contactor to weld itself shut would be lower (probably not a linear relationship), and so the risk of a problem that much lower. You may decide you can tolerate the risk without additional mitigations. ________________________________ Message 4 _____________________________________ Time: 11:28:21 PM PST US Subject: Re: AeroElectric-List: Contactors From: Etienne Phillips Hi Sacha Being able to pull the mixture control whilst on the ground will stop the engine from producing power, but if the start motor is still energised due to the failed contactor, won't it keep cranking until you pull a terminal off the battery? I'm not that familiar with the starters used in aviation (I hand-swing my engine), so am unsure if they have a disengage mechanism like they do on cars. Thanks Etienne On 4 November 2013 00:07, Sacha wrote: > > Thanks Peter > Actually I realized today that I can easily use the semi-useless > alternator off warning light that I fitted on my panel as a "starter on > warning light" with minimal rewiring. Since 99.9% of the time I'm going to > be on the ground while starting my engine, I think I can live with the > fact of not being able to disable the starter motor if the contactor gets > stuck somehow since I can just shut down the engine. > Out of interest I will try to measure how many amps are drawn by the > starter next time I'm down at the hangar. Though I suspect this would vary > somewhat depending on temperature. > I've almost finished the CAD drawings of my electrical system so I'll be > submitting them to the list for review and criticism soon. > Sacha > > On Nov 3, 2013, at 21:42, Peter Pengilly wrote: > > > Apologies, I'm not very familiar with Rotax components. It would be good > to know how much current a Rotax starter pulls - I guess it is likely that > as the engine is only 1200cc the draw would rather less than a starter for > a 5/6 litre Lyc. I believe a Lyc starter pulls between 200 to 500A > depending on starter type and compression ratio. If a Rotax pulls > substantially less the potential for the starter contactor to weld itself > shut would be lower (probably not a linear relationship), and so the risk > of a problem that much lower. You may decide you can tolerate the risk > without additional mitigations. > > ------------------------------------------------------------------------------------- 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.