---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 04/16/07: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:02 AM - Re: Battery insulation (B Tomm) 2. 12:10 AM - Formation flying attenuator (B Tomm) 3. 05:44 AM - Re: Re: Battery insulation (Robert L. Nuckolls, III) 4. 05:47 AM - Re: Formation flying attenuator (Robert L. Nuckolls, III) 5. 05:50 AM - Re: Battery insulation (Robert L. Nuckolls, III) 6. 05:58 AM - Re: curious questions (Robert L. Nuckolls, III) 7. 06:19 AM - Re: interesting failure(s) (Ken) 8. 06:19 AM - Re: interesting failure(s) (Robert L. Nuckolls, III) 9. 07:48 AM - Re: interesting failure(s) (Robert L. Nuckolls, III) 10. 02:51 PM - Re: Flight Tech Intercom and Microair 760 COM (Ron Brown) 11. 06:17 PM - Re: Flight Tech Intercom and Microair 760 COM (Ken) 12. 07:53 PM - Re: interesting failure(s) (Robert L. Nuckolls, III) 13. 10:24 PM - Re: interesting failure(s) (Ron Quillin) ________________________________ Message 1 _____________________________________ Time: 12:02:10 AM PST US From: "B Tomm" Subject: RE: AeroElectric-List: Battery insulation What about the expanding foam from a aerosol can commonly used for insulating around doors/windows etc. Bevan -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of rtitsworth Sent: Sunday, April 15, 2007 9:29 PM Subject: RE: AeroElectric-List: Battery insulation --> Bob, etal, If a foam spacer is not a problem, is there any thought behind using something similar to help insulate/isolate a battery from the ships vibration like thin rubber (baffling matgerial) or thin memory foam, etc. Rick -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Sunday, April 15, 2007 10:09 PM Subject: Re: AeroElectric-List: Battery insulation At 01:16 PM 4/14/2007 -0700, you wrote: > >A friend has a Cherokee 140 with an original battery box beneath the >rear seat. He has replaced the lead acid battery with a 16 AH RG >battery. The RG battery is oriented the same as the lead acid battery >had been. To keep the new battery from flopping around (it is much >smaller than the old lead acid one) he inserted DOW HI (blue board >foam) insulation around the four sides. I don't recall seeing any >insulation under or over the battery. My >question: Is this insulation OK or is there a chance that the battery >could overheat if under heavy recharge? No > The installation looks nice and tidy and is very lightweight, but I'd > like to make sure he is not set up for a problem in flight. Please > comment if you can. The foam will be fine and lighter than plywood. We did use thin plywood to fill the gap around an RG battery when we STC'd the first B&C product onto the C-150 and many other airplanes later. But with greater thickness you're discussing, the foam would be better. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 2 _____________________________________ Time: 12:10:43 AM PST US From: "B Tomm" Subject: AeroElectric-List: Formation flying attenuator Bob, You have a drawing for "Formation flying attenuator". I'm wondering if I will need this. Can you tell me if I will need this? My radios are SL30 and SL60. Bevan RV7A wiring ________________________________ Message 3 _____________________________________ Time: 05:44:24 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Battery insulation At 10:04 PM 4/14/2007 -0400, you wrote: >In a message dated 4/14/2007 8:13:28 P.M. Central Daylight Time, >leoh@gci.net writes: >Bob, > >The battery is not approved for the Cherokee but is FAA PMA' d and >approved for many others I'm told. They will need a 337 to finish the >install per his AI. > >Leo >Thank You Leo, > >In the event something leaks, has anyone yet investigated the suitability >of the foam when it gets involved with corrosive gases? May not be >considered a problem, but --- ?? > RG batteries don't leak. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 4 _____________________________________ Time: 05:47:36 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Formation flying attenuator At 12:10 AM 4/16/2007 -0700, you wrote: >Bob, > >You have a drawing for "Formation flying attenuator". I'm wondering if I >will need this. Can you tell me if I will need this? My radios are SL30 >and SL60. Don't know until you try it. And the value of a formation flying attenuator cuts both ways. Maybe YOUR receiver doesn't strangle on very strong signals but others in the formation might. The attenuator attenuates both your incoming signal and outgoing signal. The repeatable experiment is the final arbiter. Bob . . . ________________________________ Message 5 _____________________________________ Time: 05:50:30 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Battery insulation At 08:10 AM 4/15/2007 -0700, you wrote: > > >In addition to the issues of possible heat buildup, chemical interaction, >hard landing consequences, and FAA requirements, you might want to >consider the blue plastic is most likely extruded polystyrene, one of the >most combustible of expanded plastics. Expanded polyiso insulation would >be better in that regard, but may be worse chemically (the rest of the >name is ...isocyanurate!). > >To me, the idea does not seem too cool. If you need the 337 for the AI to >buy off on this, could that include elimination of the battery box >altogether? In lieu of the box, install a properly anchored platform and >tie-down for the battery. Best idea yet. Bob . . . ________________________________ Message 6 _____________________________________ Time: 05:58:06 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: curious questions At 04:18 PM 4/15/2007 -0800, you wrote: >Doug, > >Thanks for the very good reply. I forwarded this to my friend and I am >sure he will like it better than my usual, "Because that is the way it >says to do it on the Z-11 drawing". Good job Doug. Bob . . . ________________________________ Message 7 _____________________________________ Time: 06:19:41 AM PST US From: Ken Subject: Re: AeroElectric-List: interesting failure(s) Why would anyone bridge a contactor with a transorb? AFAIK transorbs should always go to ground. Ken Eric Whiteside wrote: > I thought the List might be interested in this sequence of failures. > Aircraft is an A36 Bonanza. > > When 10 miles out on approach to St. Pete, the right seat passenger > said he smelled burning insulation. > > The pilot did not notice anything. He dropped gear, flaps, landed and > taxied in without incident. > > All appeared normal with the exception of the JPI EGT/CHT/Fuel Flow > instrument, which had gone dark at some point. > > The pilot turned off the master switch, but then noticed the strobe > was still flashing and there continued to be power to the panel, > radios, etc. > > The pilot disconnected a battery cable to interrupt power. I flew in > shortly after and attempted to diagnose the problem. > > > > Based on the pilots description of events, I assumed the master > contactor had welded itself closed, > > but measurements with a borrowed VOM showed no continuity across the > contactor main terminals. > > Further investigation uncovered that the transorb devices attached to > the contactor terminals had failed shorted > > in such a way as to bridge current around the contactor. Measurements > showed the contactor coil was failed open. > > (All of these measurements were made out of circuit with wires & > devices isolated.) > > > > When the mag/starter switch was subsequently turned to start, the > starter twitched and the > > transorbs instantly failed open due to the large starter current draw. > > > > No current limiters had opened and no circuit breakers tripped. > > > > The master contactor was replaced, the aircraft flown home and the JPI > instrument was removed and sent to the factory for repair. > > There was an obvious burned smell inside the case. > > > > My understanding is that on the Bonanza the alternator will continue > to power the buss when the master is turned off, > > (or fails, as in this case). I assume that is why the large loads of > the gear motor and flap motor were supported. > > > > I would be interested in any analysis as to which might have been the > causes and which might have been the effects, > > of the failures described above. Is it likely that the contactor coil > failed open, and the resulting opening of the contactor > > created some sort of transient that caused the transorbs to fail > shorted, and which also damaged the JPI? > > > > Or is some other sequence of events more likely? > > > > Eric W. > > > ________________________________ Message 8 _____________________________________ Time: 06:19:41 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: interesting failure(s) At 11:57 AM 4/15/2007 -0400, you wrote: >I thought the List might be interested in this sequence of >failures. Aircraft is an A36 Bonanza. > >When 10 miles out on approach to St. Pete, the right seat passenger said >he smelled burning insulation. > >The pilot did not notice anything. He dropped gear, flaps, landed and >taxied in without incident. > >All appeared normal with the exception of the JPI EGT/CHT/Fuel Flow >instrument, which had gone dark at some point. > >The pilot turned off the master switch, but then noticed the strobe was >still flashing and there continued to be power to the panel, radios, etc. > >The pilot disconnected a battery cable to interrupt power. I flew in >shortly after and attempted to diagnose the problem. > > >Based on the pilot s description of events, I assumed the master contactor >had welded itself closed, > >but measurements with a borrowed VOM showed no continuity across the >contactor main terminals. > >Further investigation uncovered that the transorb devices attached to the >contactor terminals had failed shorted > >in such a way as to bridge current around the contactor. Measurements >showed the contactor coil was failed open. > >(All of these measurements were made out of circuit with wires & devices >isolated.) > > >When the mag/starter switch was subsequently turned to start, the starter >twitched and the > >transorbs instantly failed open due to the large starter current draw. > > >No current limiters had opened and no circuit breakers tripped. > > >The master contactor was replaced, the aircraft flown home and the JPI >instrument was removed and sent to the factory for repair. > >There was an obvious burned smell inside the case. > > >My understanding is that on the Bonanza the alternator will continue to >power the buss when the master is turned off, > >(or fails, as in this case). I assume that is why the large loads of the >gear motor and flap motor were supported. > > >I would be interested in any analysis as to which might have been the >causes and which might have been the effects, > >of the failures described above. Is it likely that the contactor coil >failed open, and the resulting opening of the contactor > >created some sort of transient that caused the transorbs to fail shorted, >and which also damaged the JPI? > > >Or is some other sequence of events more likely? Your hypothesis is pretty well supported by the simple ideas. I can't think of an alternative scenario at the moment. Yes, this series of Beechcraft products offer independent control of battery and alternator. The alternators on these aircraft will self excite and the folks at Beech wanted to take advantage of an alternative mode of operation should the battery contactor fail. I wasn't aware that there were transorbs around the fat-terminals of these contactors. I'll pull the drawings today and see if I can find when they might have been added. I'm suspicious that someone else sprinkled these on at some later time. Failure in the JPI device was probably a separate incident promoted by some perturbation on the bus when the battery went off line. I designed a regulator for Beech that was specified not to interfere with the self-exciting nature of Beech's alternators but here were no specifications for voltage regulator dynamic response with a battery off line. I did a Google site search for DO-160 on JPI's website and found ONE and only ONE reference to this valuable test plan . . . and that refererence was exceedingly brief and short of information. Getting to wear the DO-160 gold star on your butt for having successfully jumped all the DO-160 hoops is not a trivial task. Had they rigorously applied all the suggested criteria in the design of their products, I would think that this fact would have been prominently cited on the literature for all their products. Given the short shrift offered on their literature with respect to DO-160, I'm guessing that the instrument died as a result of an abnormal but predictable voltage excursion that did not affect other systems. I can find no error in your hypothesis sir. I'll check into the Transorb thing. Bob . . . ________________________________ Message 9 _____________________________________ Time: 07:48:06 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: interesting failure(s) At 09:13 AM 4/16/2007 -0400, you wrote: > >Why would anyone bridge a contactor with a transorb? AFAIK transorbs >should always go to ground. >Ken Or across the offending antagonist . . . Bob . . . ________________________________ Message 10 ____________________________________ Time: 02:51:38 PM PST US From: "Ron Brown" Subject: Re: AeroElectric-List: Flight Tech Intercom and Microair 760 COM I am pulling all my hair out trying to figure out why a friend's intercom and COM radio aren't working together. This is a Flight Tech 402 panel mounted intercom and a Microair 760 COM radio. The intercom works - pilot and copilot can communicate with each other, both can hear radio transmissions but neither can transmit on the radio. The transmit light comes on, when the PTT is pressed, the squelch is broken (ie carrier is being transmitted, but no audio). Turning the intercom off has the same results. I have rung the wiring out, checked continuity and grounds and made sure there are shorts. I can remove the intercom, and place jumpers between pins 2-3 (headphone); 6-7 (pilot mike) and 9-10 (PTT), and the radio works just perfectly. When checking the intercom on the bench, I get continuity between each of the pairs above (diode present on 9-10). What's my problem????????? THANKS ________________________________ Message 11 ____________________________________ Time: 06:17:23 PM PST US From: Ken Subject: Re: AeroElectric-List: Flight Tech Intercom and Microair 760 COM Hi Ron You might want to call or email Flighttech? There was a circuit board glitch in their early production boards that caused transmit problems specifically with the icom radio. And although very rare, it is always possible to have a bad transmit relay. You should hear the relay click if you put your ear by the intercom when you key the mic. I think you'll find the support and warranty is excellant and I am sure delighted with that intercom. Ken Ron Brown wrote: > > > I am pulling all my hair out trying to figure out why a friend's > intercom and COM radio aren't working together. > > This is a Flight Tech 402 panel mounted intercom and a Microair 760 > COM radio. The intercom works - pilot and copilot can communicate > with each other, both can hear radio transmissions but neither can > transmit on the radio. The transmit light comes on, when the PTT is > pressed, the squelch is broken (ie carrier is being transmitted, but > no audio). Turning the intercom off has the same results. > > I have rung the wiring out, checked continuity and grounds and made > sure there are shorts. > > I can remove the intercom, and place jumpers between pins 2-3 > (headphone); 6-7 (pilot mike) and 9-10 (PTT), and the radio works just > perfectly. > > When checking the intercom on the bench, I get continuity between each > of the pairs above (diode present on 9-10). > > What's my problem????????? > > THANKS ________________________________ Message 12 ____________________________________ Time: 07:53:58 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: interesting failure(s) > > > I can find no error in your hypothesis sir. I'll check > into the Transorb thing. > > Bob . . . I dug through some F33 and A36 drawings today and as far as I had time to research today, the first diodes to go onto the battery master contactor was a pair of 1N4007, 1A devices from EACH fat terminal to the (+) side of the coil terminal this permitted a battery contactor to close using power from either a good battery or a bus powered from ground power. Our ground power jacks drove the bus side of the battery contactor . . . so the diodes made sure that you could get the contactor closed from ground power if the battery were dead. See . . . http://www.aeroelectric.com/temp/Early_Battery_Master.jpg Some years later, a 1.5KE51CA (bi-directional, 51v TVS) was added across the coil of the battery contactor. See . . . http://www.aeroelectric.com/temp/Later_Battery_Master.jpg I wasn't able to chase down the 14v versions in the time I had but some graybeards told me that the first airplanes had no diodes at all and one of the thought some models added diodes across the coil later. In any case, what you saw on the problem aircraft could have been a combination of two diodes between the contactor fat terminals . . . and perhaps a TVS across the coild. Bob . . . ________________________________ Message 13 ____________________________________ Time: 10:24:17 PM PST US Subject: Re: AeroElectric-List: interesting failure(s) From: Ron Quillin At 20:52 4/16/2007, you wrote: > > I dug through some F33 and A36 drawings today and as far > as I had time to research today, the first diodes to go > onto the battery master contactor was a pair of 1N4007, > 1A devices from EACH fat terminal to the (+) side of the > coil terminal this permitted a battery contactor to close > using power from either a good battery or a bus powered from > ground power. >Our ground power jacks drove the bus > side of the battery contactor . . . so the diodes made > sure that you could get the contactor closed from > ground power if the battery were dead. See . . . > >http://www.aeroelectric.com/temp/Early_Battery_Master.jpg From the early jpg you posted, and it's a bit difficult to clearly see, it appears CR24 has it's anode connected to the coil of K15 and the cathode to the battery and fat terminal of K15. If this is correct, this diode would be reverse biased by the battery and could not provide any current to the relay coil, but rather a discharge path for the collapsing field of the relay when de-energized. Diode CR25 OTOH, with it's cathode connected to the coil, would provide a current path for energizing power to the relay, assuming a voltage was present on bus M24 or M25(?). So, as drawn, K15 would only be energized with power on the M bus and with S29 closed. Is this an error in the schematic or just an artifact of the scan? > Some years later, a 1.5KE51CA (bi-directional, 51v TVS) > was added across the coil of the battery contactor. See . . . > >http://www.aeroelectric.com/temp/Later_Battery_Master.jpg On the later jpg, both CR24 and CR25 appear to have their cathodes connected to the high coil terminal. With S29 closed and energizing voltage present at either the M bus or battery the coil and relay, as you state, could be energized. This seems like the correct configuration. > I wasn't able to chase down the 14v versions in the time > I had but some graybeards told me that the first airplanes > had no diodes at all and one of the thought some models > added diodes across the coil later. > > In any case, what you saw on the problem aircraft could > have been a combination of two diodes between the contactor > fat terminals . . . and perhaps a TVS across the coild. > > Bob . . . Interesting thread, Thanks Ron Q. ------------------------------------------------------------------------------------- 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.