---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 07/05/13: 20 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:06 AM - Re: Low voltage indicator with dual alternators (Robert L. Nuckolls, III) 2. 06:09 AM - Re: Master/Battery/Alt Field vs. Master/Battery and Alt Field... (Robert L. Nuckolls, III) 3. 09:32 AM - solenoid wiring question (cardinalnsb) 4. 09:34 AM - Re: Master/Battery/Alt Field vs. Master/Battery and Alt Field... (Michael Burbidge) 5. 09:38 AM - Re: solenoid wiring question (Bill Bradburry) 6. 10:50 AM - Re: solenoid wiring question (Robert L. Nuckolls, III) 7. 10:54 AM - Re: Master/Battery/Alt Field vs. Master/Battery and Alt Field... (Robert L. Nuckolls, III) 8. 11:28 AM - Re: Re: Master Switch/Contactor and Starter Questions (Ed) 9. 11:28 AM - Re: Master/Battery/Alt Field vs. Master/Battery and Alt Field... (Michael Burbidge) 10. 11:34 AM - Re: Low voltage indicator with dual alternators (donjohnston) 11. 11:59 AM - Re: Re: Master Switch/Contactor and Starter Questions (Bill Putney) 12. 12:25 PM - Re: Re: Master Switch/Contactor and Starter Questions (Robert L. Nuckolls, III) 13. 12:27 PM - Re: Re: Low voltage indicator with dual alternators (Robert L. Nuckolls, III) 14. 12:29 PM - Re: Re: Master Switch/Contactor and Starter Questions (Robert L. Nuckolls, III) 15. 02:16 PM - Re: Low voltage indicator with dual alternators (Bill Watson) 16. 02:27 PM - solenoid wiring question (cardinalnsb) 17. 07:52 PM - Re: Master/Battery/Alt Field vs. Master/Battery and Alt Field... (user9253) 18. 09:29 PM - Re: Re: Master Switch/Contactor and Starter Questions (Ed) 19. 09:55 PM - Re: Re: Master Switch/Contactor and Starter Questions (Ed) 20. 10:08 PM - Re: solenoid wiring question (Ed) ________________________________ Message 1 _____________________________________ Time: 06:06:42 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Low voltage indicator with dual alternators At 04:47 PM 7/4/2013, you wrote: > >I'm going to have a 60a primary and a 20a secondary alternator with >B&C LR3C and LS1A voltage regulators respectively. > >If in the event of a primary alternator failure, and I switch to the >secondary, will the primary low voltage warning light (off of LR3C, >pin 5) remain illuminated? Or will switching off that alternator >open the low voltage circuit? No, the OV and LV sense lines along with power to run those systems is independent of the regulator circuits. The LV warning systems will function whether or not the alternator is powered. Bob . . . ________________________________ Message 2 _____________________________________ Time: 06:09:23 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Master/Battery/Alt Field vs. Master/Battery and Alt Field... At 02:16 PM 7/4/2013, you wrote: > >I'm sure I read a discussion of this question somewhere but can't find it. > >I'm building an RV-9A, basic day/night VFR. I'm using the Basic >Day/Night VFR system diagram available from B&C website. It is >almost identical to the Z-11 diagram in Bob's book. One difference >is that the Z-11 uses a 2 poll 3-throw switch (2-10) for the master, >so that the alternator can be switched on after start. The Basic VFR >diagram from B&C uses a 2 poll 2 throw switch (2-3) so that the >alternator field is on during start. > >What are the advantages of isolating the alternator field during >startup? My airplane has a B&C 40 amp alternator. Which approach >would you recommend? None. The choice of switches depends on how you plan to disable the alternator during battery only operations. If you have a field supply breaker that can be pulled, then the simple 2 pole, 2 throw switch is fine. If you've gone the crowbar ov protection route then the breaker should be present. Alternatively, the 3-position switch duplicates the legacy control philosophy that allows a battery to be turned on without the alternator . . . like the split rocker switch. Bob . . . ________________________________ Message 3 _____________________________________ Time: 09:32:57 AM PST US From: cardinalnsb Subject: AeroElectric-List: solenoid wiring question Re figure 5 of Bob's diagram of adding a starter contactor upstream of the original starter solenoid: Is there any reason not to wire the fat wire to the starter side of the old original starter solenoid, with a jumper from the fat wire terminal back to the old starter solenoid energizer terminal. The point would be to eliminate the high current having to flow through the old starter solenoid disc, since the high current is being controlled by the new upstream starter contactor. Thanks, Skip Simpson In a message dated 07/05/13 03:12:33 Eastern Daylight Time, aeroelectric-list@matronics.com writes: * ================================================== Online Versions of Today's List Digest Archive ================================================== Today's complete AeroElectric-List Digest can also be found in either of the two Web Links listed below. The .html file includes the Digest formatted in HTML for viewing with a web browser and features Hyperlinked Indexes and Message Navigation. The .txt file includes the plain ASCII version of the AeroElectric-List Digest and can be viewed with a generic text editor such as Notepad or with a web browser. HTML Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter 13-07-04&Archive=AeroElectric Text Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter 13-07-04&Archive=AeroElectric ================================================ EMail Version of Today's List Digest Archive ================================================ ---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 07/04/13: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:32 AM - Re: Boeing switches (Eric M. Jones) 2. 06:20 AM - Re: Re: Master Switch/Contactor and Starter Questions (Robert L. Nuckolls, III) 3. 07:29 AM - Re: Re: Boeing switches (Robert L. Nuckolls, III) 4. 11:00 AM - Narco Transponder Tray Coax Connector () 5. 11:05 AM - Re: Re: Boeing switches (Jay Hyde) 6. 12:17 PM - Master/Battery/Alt Field vs. Master/Battery and Alt Field... (Michael Burbidge) 7. 02:48 PM - Low voltage indicator with dual alternators (donjohnston) 8. 02:57 PM - Re: Narco Transponder Tray Coax Connector (Bill Putney) 9. 03:22 PM - Re: Re: Boeing switches (Robert L. Nuckolls, III) 10. 03:42 PM - Re: Narco Transponder Tray Coax Connector () ________________________________ Message 1 _____________________________________ Time: 05:32:21 AM PST US Subject: AeroElectric-List: Re: Boeing switches From: "Eric M. Jones" My two cents: Using two parallel switches to prevent trim runaway seems boneheaded, and wouldn't stand a thorough engineering fault-tree review. Furthermore I'd bet that it never prevented ANY problem from occurring. Sure, I understand the intention, but I don't think it's good engineering. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=403912#403912 ________________________________ Message 2 _____________________________________ Time: 06:20:29 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions At 07:13 PM 7/3/2013, you wrote: > > >I agree. It seems pointless to have 2 solenoids operating at the >same time. The other issue is that I believe the Subaru solenoid >moves the gear before the contactor part puts juice to the motor >brushes. An aircraft type contactor would do both at the same time >rather than sequentially. Have not dismantled one so I may be in error. None of applications of an external contactor proposed for modern starters "bypasses" functionality of the built in solenoid/contactor. The starter's built in solenoids do engage the pinion gear before closing electrical connection for the starter motor. Variants to select from when using these modern starters causes the builder to decide whether the built in contactor is energized by the panel mounted, START switch -OR- energized through a more robust device. There is a problem to be solved when the panel mounted starter control is used to energize the starter's built in contactor. Unlike legacy 'starter solenoids' controlling starters with Bendix drives, the modern pinion engagement solenoids have a very high coil current demand during the first few milliseconds of being energized. See: http://tinyurl.com/op5cs2g Failure to recognize this difference in solenoid/contator performance caused a kerfuffle over burned start switch contacts on the ACS-510 key swicch (clone of legacy Bendix/Gerdes). ACS now sells a diode with two terminals applied. Emacs! A critical need to install this diode across the starter contactor engagement coil arose from the alarming rate at which start contacts in the key switch were destroyed by overstress when the legacy starter/external contactor combo was replaced with a light weight version with combination solenoid/ contactors. Many cars suffered similar failure modes in their key-start switches. SB92-01 from ACS originally place thier diode across the switch contacts . . . wrong place. It was corrected in a subsequent revision. See http://tinyurl.com/nva2xdy B&C adopted the philosophy of jumpering the starter solenoid coil right to the fat-wire terminal on the starter . . . and controlling power to the starter though a modern, starter contactor WITH built in coil suppression diode. The external contactor's inrush demands on the start switch are a small fraction of that for direct control. This philosophy posed a new problem when PM motor starters began to show up on the airplane. PM motors have a pronounced counter-emf during spin-down after the power is removed. This would delay disengagement of the pinion gear and was commonly called "starter run on" . . . in fact it was better called "delayed disengagement". Starters with wound fields (B&C and some others) do not suffer this indignity and function well with the engagement solenoid jumpered directly to the starter's fat-wire terminal. In ANY case, the builder's design goals should include providing a source of solenoid engagement power that (1) is supplied through a low impedance source (short and fatter than usual wires) and (2) avoid running this power through the panel mounted start switch. If the starter is a PM version, the builder can take advantage of the "I" terminal on many modern starter cotactors and use it to SUPPLY current to the engagement solenoid. This provides for instant removal of coil power when the starter switch is opened and prevents 'delayed disengagement'. In this case, the builder would do well to have diode coil suppression on BOTH the external contactor coil AND the solenoid/contactor coil on the starter. Bob . . . ________________________________ Message 3 _____________________________________ Time: 07:29:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Boeing switches At 07:29 AM 7/4/2013, you wrote: > >My two cents: > >Using two parallel switches to prevent trim runaway seems >boneheaded, and wouldn't stand a thorough engineering fault-tree >review. Furthermore I'd bet that it never prevented ANY problem from occurring. Whether or not a problem was demonstrably prevented is irrelevant to the reliability study. Good FMEA mitigation assumes that the part WILL fail. Working out a logical means by which single failures might go undetected for no more than a single tank full of fuel has been a time-honored legacy design goal. >Sure, I understand the intention, but I don't think it's good engineering. they are not used in PARALLEL. In the Boeing case, they are in series with one side controlling direction, the other side in SERIES controlling power. Each side can be explored for functionality in pre-flight, neither side capable of causing a runaway-by-sticking. Beech (and many others) uses the two spdt switches to handle one half of a PM motor UP-OFF- DN switching duty. Again, both sides easily evaluated in pre-flight, neither side capable of causing a runaway-by-sticking. Lear (and many others) uses the 'coolie hat' to drive relays that DID offer a possibility for runaway-by- sticking. But their systems architecture included a wheel-master-disconnect that removed power from all trim systems along with the autopilot. I AM aware of trim runaways in aircraft fitted with wheel master disconnects that would not have happened if the airplane had been fitted with the split trim switch where the WMD switch provided the mitigation. Bob . . . ________________________________ Message 4 _____________________________________ Time: 11:00:48 AM PST US From: Subject: AeroElectric-List: Narco Transponder Tray Coax Connector Can someone point me to the part number/source for a replacement 90-degree, bulkhead, slide-on, coax connector used on the Narco AT-150 transponder tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry them? Thanks, James ________________________________ Message 5 _____________________________________ Time: 11:05:43 AM PST US From: "Jay Hyde" Subject: RE: AeroElectric-List: Re: Boeing switches Good argument Bob.... I use a switch on the panel to power the trim, but that may be a bit far away for a quick reaction, before the trim lurks all the way to the end. Jay -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: 04 July 2013 04:29 PM Subject: Re: AeroElectric-List: Re: Boeing switches --> At 07:29 AM 7/4/2013, you wrote: >--> > >My two cents: > >Using two parallel switches to prevent trim runaway seems boneheaded, >and wouldn't stand a thorough engineering fault-tree review. >Furthermore I'd bet that it never prevented ANY problem from occurring. Whether or not a problem was demonstrably prevented is irrelevant to the reliability study. Good FMEA mitigation assumes that the part WILL fail. Working out a logical means by which single failures might go undetected for no more than a single tank full of fuel has been a time-honored legacy design goal. >Sure, I understand the intention, but I don't think it's good engineering. they are not used in PARALLEL. In the Boeing case, they are in series with one side controlling direction, the other side in SERIES controlling power. Each side can be explored for functionality in pre-flight, neither side capable of causing a runaway-by-sticking. Beech (and many others) uses the two spdt switches to handle one half of a PM motor UP-OFF- DN switching duty. Again, both sides easily evaluated in pre-flight, neither side capable of causing a runaway-by-sticking. Lear (and many others) uses the 'coolie hat' to drive relays that DID offer a possibility for runaway-by- sticking. But their systems architecture included a wheel-master-disconnect that removed power from all trim systems along with the autopilot. I AM aware of trim runaways in aircraft fitted with wheel master disconnects that would not have happened if the airplane had been fitted with the split trim switch where the WMD switch provided the mitigation. Bob . . . ________________________________ Message 6 _____________________________________ Time: 12:17:10 PM PST US From: Michael Burbidge Subject: AeroElectric-List: Master/Battery/Alt Field vs. Master/Battery and Alt Field... I'm sure I read a discussion of this question somewhere but can't find it. I'm building an RV-9A, basic day/night VFR. I'm using the Basic Day/Night VFR system diagram available from B&C website. It is almost identical to the Z-11 diagram in Bob's book. One difference is that the Z-11 uses a 2 poll 3-throw switch (2-10) for the master, so that the alternator can be switched on after start. The Basic VFR diagram from B&C uses a 2 poll 2 throw switch (2-3) so that the alternator field is on during start. What are the advantages of isolating the alternator field during startup? My airplane has a B&C 40 amp alternator. Which approach would you recommend? Thanks, Michael- ________________________________ Message 7 _____________________________________ Time: 02:48:19 PM PST US Subject: AeroElectric-List: Low voltage indicator with dual alternators From: "donjohnston" I'm going to have a 60a primary and a 20a secondary alternator with B&C LR3C and LS1A voltage regulators respectively. If in the event of a primary alternator failure, and I switch to the secondary, will the primary low voltage warning light (off of LR3C, pin 5) remain illuminated? Or will switching off that alternator open the low voltage circuit? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=403960#403960 ________________________________ Message 8 _____________________________________ Time: 02:57:44 PM PST US From: Bill Putney Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector It's TED 9-30-10 connector. These are solder on connectors and have the lowest profile (depth-wise). http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html You should check with them to make sure a snap ring is included or you may have to buy it separately. There's also a DBA-600 that is a connector like you want with a female BNC so you don't have a cable attached to your tray. You put a BNC on the cable and connect it to this adapter. About the same price as the 9-30-10 but of course you have to do the BNC too. http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSnap-Ring.html Bill On 7/4/13 10:59 AM, berkut13@berkut13.com wrote: > Can someone point me to the part number/source for a replacement > 90-degree, > bulkhead, slide-on, coax connector used on the Narco AT-150 transponder > tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry > them? > > Thanks, > James > * > > > * ________________________________ Message 9 _____________________________________ Time: 03:22:42 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Re: Boeing switches At 01:05 PM 7/4/2013, you wrote: > >Good argument Bob.... I use a switch on the panel to power the trim, but >that may be a bit far away for a quick reaction, before the trim lurks all >the way to the end. You would do well to deduce the severity of a trim runaway. Is the airplane controllable with full trim either up or down? How fast does the trim run with respect to pilot reaction times needed to deal with a runaway? Are there stops or limits to trim excursion necessary for the full range of CG envelopes or will the system produce more pitch authority than would ever be necessary for normal operations? In a Lear, at Mach cruise, the system is manually failed and the pilot is obligated to keep hands in the lap for 3 seconds. Only then can he move to deal with the situation. After achieving a stable, safe condition, recorded data is analyzed for busting limits on attitude, altitude and airspeed excursions. The exercise is repeated and trim speeds then adjusted until a sweat-free, runaway recovery is assured. The trim systems I've seen in some TC aircraft are so slow that unexpected trims under worst case conditions are no big deal. But what's the story for YOUR airplane? Yes, if trim speeds are brisk, trim authority high and you have good reason for not reducing them, then some form of inarguable override is indicated. Instructing the pilot to pull a breaker for taming a trim runaway is generally not acceptable . . . even panel mounted switche situated amongst other switches will get you frowns from the human factors guys. At the same time, find out just how much risk is associated with an uncontrolled trim event and see if that can be engineered out as opposed to stacking emergency ops hardware on top of the design. Bob . . . ________________________________ Message 10 ____________________________________ Time: 03:42:25 PM PST US From: Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector Excellent! Exactly what I needed. Thanks. From: Bill Putney Sent: Thursday, July 04, 2013 4:57 PM Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector It's TED 9-30-10 connector. These are solder on connectors and have the lowest profile (depth-wise). http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html You should check with them to make sure a snap ring is included or you may have to buy it separately. There's also a DBA-600 that is a connector like you want with a female BNC so you don't have a cable attached to your tray. You put a BNC on the cable and connect it to this adapter. About the same price as the 9-30-10 but of course you have to do the BNC too. http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSnap-Ring.html Bill On 7/4/13 10:59 AM, berkut13@berkut13.com wrote: Can someone point me to the part number/source for a replacement 90-degree, bulkhead, slide-on, coax connector used on the Narco AT-150 transponder tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry them? Thanks, James ________________________________ Message 4 _____________________________________ Time: 09:34:32 AM PST US Subject: Re: AeroElectric-List: Master/Battery/Alt Field vs. Master/Battery and Alt Field... From: Michael Burbidge I'm using the LR3C-14 external regulator and fuse blocks from B&C. My field supply includes a fuse in my fuse block but I cannot pull the fuse during flight. It sounds like I should either move the field supply to a breaker on the panel that I can pull, or use the 3-position switch. Another question. All of my 250 hours of flight are in a 1959 C172, which has a generator. There is a master switch with two positions. My question is under what conditions would one operate "battery only"? Thanks for the help, Michael- On Jul 5, 2013, at 6:08 AM, "Robert L. Nuckolls, III" wrote: > > At 02:16 PM 7/4/2013, you wrote: >> >> I'm sure I read a discussion of this question somewhere but can't find it. >> >> I'm building an RV-9A, basic day/night VFR. I'm using the Basic Day/Night VFR system diagram available from B&C website. It is almost identical to the Z-11 diagram in Bob's book. One difference is that the Z-11 uses a 2 poll 3-throw switch (2-10) for the master, so that the alternator can be switched on after start. The Basic VFR diagram from B&C uses a 2 poll 2 throw switch (2-3) so that the alternator field is on during start. >> >> What are the advantages of isolating the alternator field during startup? My airplane has a B&C 40 amp alternator. Which approach would you recommend? > > None. The choice of switches depends on > how you plan to disable the alternator during > battery only operations. If you have a field > supply breaker that can be pulled, then the > simple 2 pole, 2 throw switch is fine. If > you've gone the crowbar ov protection route > then the breaker should be present. > > Alternatively, the 3-position switch duplicates > the legacy control philosophy that allows a > battery to be turned on without the alternator . . . > like the split rocker switch. > > > > Bob . . . > > > > ________________________________ Message 5 _____________________________________ Time: 09:38:54 AM PST US From: "Bill Bradburry" Subject: RE: AeroElectric-List: solenoid wiring question That would engage the starter motor before the solenoid engages the flywheel with the starter drive gear. It could cause a mess! B2 _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of cardinalnsb Sent: Friday, July 05, 2013 12:28 PM Subject: AeroElectric-List: solenoid wiring question Re figure 5 of Bob's diagram of adding a starter contactor upstream of the original starter solenoid: Is there any reason not to wire the fat wire to the starter side of the old original starter solenoid, with a jumper from the fat wire terminal back to the old starter solenoid energizer terminal. The point would be to eliminate the high current having to flow through the old starter solenoid disc, since the high current is being controlled by the new upstream starter contactor. Thanks, Skip Simpson In a message dated 07/05/13 03:12:33 Eastern Daylight Time, aeroelectric-list@matronics.com writes: * ================================================== Online Versions of Today's List Digest Archive ================================================== Today's complete AeroElectric-List Digest can also be found in either of the two Web Links listed below. The .html file includes the Digest formatted in HTML for viewing with a web browser and features Hyperlinked Indexes and Message Navigation. The .txt file includes the plain ASCII version of the AeroElectric-List Digest and can be viewed with a generic text editor such as Notepad or with a web browser. HTML Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter 13-07-04&Archive=AeroElectric Text Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter 2013-07-04&Archive=AeroElectric ============================ ==================== EMail Version of Today's List Digest Archive ================================================ ---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 07/04/13: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:32 AM - Re: Boeing switches (Eric M. Jones) 2. 06:20 AM - Re: Re: Master Switch/Contactor and Starter Questions (Robert L. Nuckolls, III) ; 3. 07:29 AM - Re: Re: Boeing switches (Robert L. Nuckolls, III) 4. 11:00 AM - Narco Transponder Tray Coax Connector () 5. 11:05 AM - Re: Re: Boeing switches (Jay Hyde) 6. 12:17 PM - Master/Battery/Alt Field vs. Master/Battery and Alt Field... (Michael Burbidge) 7. 02:48 PM - Low voltage indicator with dual alternators (donjohnston) 8. 02:57 PM - Re: Narco Transponder Tray Coax Connector (Bill Putney) 9. 03:22 PM - Re: Re: Boeing switches (Robert L. Nuckolls, III) 10. 03:42 PM - Re: Narco Transponder Tray Coax Connector () ________________________________ Message 1 _____________________________________ Time: 05:32:21 AM PST US Subject: AeroElectric-List: Re: Boeing switches From: "Eric M. Jones" My two cents: Using two parallel switches to prevent trim runaway seems boneheaded, and wouldn't stand a thorough engineering fault-tree review. Furthermore I'd bet that it never prevented ANY problem from occurring. Sure, I understand the intention, but I don't think it's good engineering. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=403912#403912 ________________________________ Message 2 _____________________________________ Time: 06:20:29 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions At 07:13 PM 7/3/2013, you wrote: > > >I agree. It se ems pointless to have 2 solenoids operating at the >same time. The other issue is that I believe the Subaru solenoid >moves the gear before the contactor part puts juice to the motor >brushes. An aircraft type contactor would do both at the same time >rather than sequentially. Have not dismantled one so I may be in error. None of applications of an external contactor proposed for modern starters "bypasses" functionality of the built in solenoid/contactor. The starter's built in solenoids do engage the pinion gear before closing electrical connection for the starter motor. Variants to select from when using these modern starters causes the builder to decide whether the built in contactor is energized by the panel mounted, START switch -OR- energized through a more robust device. There is a problem to be solved when the panel mounted starter control is used to energize the starter's built in contactor. Unlike legacy 'starter solenoids' controlling starters with Bendix drives, the modern pinion engagement solenoids have a very high coil current demand during the first few milliseconds of being energized. See: http://tinyurl.com/op5cs2g Failure to recognize this difference in solenoid/contator performance caused a kerfuffle over burned start switch contacts on the ACS-510 key swicch (clone of legacy Bendix/Gerdes). ACS now sells a diode with two terminals applied. Emacs! A critical need to install this diode across the starter contactor engagement coil arose from the alarming rate at which start contacts in the key switch were destroyed by overstress when the legacy starter/external contactor combo was replaced with a light weight version with combination solenoid/ contactors. Many cars suffered similar failure modes in their key-start switches. SB92-01 from ACS originally place thier diode across the switch contacts . . . wrong place. It was corrected in a subsequent revision. See http://tinyurl.com/nva2xdy B&C adopted the philosophy of jumpering the starter solenoid coil right to the fat-wire terminal on the starter . . . and controlling power to the starter though a modern, starter contactor WITH built in coil suppression diode. The external contactor's inrush demands on the start switch are a small fraction of that for direct control. This philosophy posed a new problem when PM motor starters began to show up on the airplane. PM motors have a pronounced counter-emf during spin-down after the power is removed. This would delay disengagement of the pinion gear and was commonly called "starter run on" . . . in fact it was better called "delayed disengagement". Starters with wound fields (B&C and some others) do not suffer this indignity and function well with the engagement solenoid jumpered directly to the starter's fat-wire terminal. In ANY case, the builder's design goals should include providing a source of solenoid engagement power that (1) is supplied through a low impedance source (short and fatter than usual wires) and (2) avoid running this power through the panel mounted start switch. If the starter is a PM version, the builder can take advantage of the "I" terminal on many modern starter cotactors and use it to SUPPLY current to the engagement solenoid. This provides for instant removal of coil power when the starter switch is opened and prevents 'delayed disengagement'. In this case, the builder would do well to have diode coil suppression on BOTH the external contactor coil AND the solenoid/contactor coil on the starter. Bob . . . ________________________________ Message 3 _____________________________________ Time: 07:29:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Boeing switches At 07:29 AM 7/4/2013, you wrote: > >My two cents: > >Using two parallel switches to prevent trim runaway seems >boneheaded, and wouldn't stand a thorough engineering fault-tree >review. Furthermore I'd bet that it never prevented ANY problem from occurring. Whether or not a problem was demonstrably prevented is irrelevant to the reliability study. Good FMEA mitigation assumes that the part WILL fail. Working out a logical means by which single failures might go undetected for no more than a single tank full of fuel has been a time-honored legacy design goal. >Sure, I understand the intention, but I don't think it's good engineering. they are not used in PARALLEL. In the Boeing case, they are in series with one side controlling direction, the other side in SERIES controlling power. Each side can be explored for functionality in pre-flight, neither side capable of causing a runaway-by-sticking. Beech (and many others) uses the two spdt switches to handle one half of a PM motor UP-OFF- DN switchin g duty. Again, both sides easily evaluated in pre-flight, neither side capable of causing a runaway-by-sticking. Lear (and many others) uses the 'coolie hat' to drive relays that DID offer a possibility for runaway-by- sticking. But their systems architecture included a wheel-master-disconnect that removed power from all trim systems along with the autopilot. I AM aware of trim runaways in aircraft fitted with wheel master disconnects that would not have happened if the airplane had been fitted with the split trim switch where the WMD switch provided the mitigation. Bob . . . ________________________________ Message 4 _____________________________________ Time: 11:00:48 AM PST US From: Subject: AeroElectric-List: Narco Transponder Tray Coax Con nector Can someone point me to the part number/source for a replacement 90-degree, bulkhead, slide-on, coax connector used on the Narco AT-150 transponder tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry them? Thanks, James ________________________________ Message 5 _____________________________________ Time: 11:05:43 AM PST US From: "Jay Hyde" Subject: RE: AeroElectric-List: Re: Boeing switches Good argument Bob.... I use a switch on the panel to power the trim, but that may be a bit far away for a quick reaction, before the trim lurks all the way to the end. Jay -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: 04 July 2013 04:29 PM Subject: Re: AeroElect ric-List: Re: Boeing switches --> At 07:29 AM 7/4/2013, you wrote: >--> > >My two cents: > >Using two parallel switches to prevent trim runaway seems boneheaded, >and wouldn't stand a thorough engineering fault-tree review. >Furthermore I'd bet that it never prevented ANY problem from occurring. Whether or not a problem was demonstrably prevented is irrelevant to the reliability study. Good FMEA mitigation assumes that the part WILL fail. Working out a logical means by which single failures might go undetected for no more than a single tank full of fuel has been a time-honored legacy design goal. >Sure, I understand the intention, but I don't think it's good engineering. they are not used in PARALLEL. In the Boeing case, the y are in series with one side controlling direction, the other side in SERIES controlling power. Each side can be explored for functionality in pre-flight, neither side capable of causing a runaway-by-sticking. Beech (and many others) uses the two spdt switches to handle one half of a PM motor UP-OFF- DN switching duty. Again, both sides easily evaluated in pre-flight, neither side capable of causing a runaway-by-sticking. Lear (and many others) uses the 'coolie hat' to drive relays that DID offer a possibility for runaway-by- sticking. But their systems architecture included a wheel-master-disconnect that removed power from all trim systems along with the autopilot. I AM aware of trim runaways in aircraft fitted with wheel master disconnects that would not have happened if the airplane had been fitted with the split trim switch where the WMD switch provided the mitigation. Bob . . . ________________________________ Message 6 _____________________________________ Time: 12:17:10 PM PST US From: Michael Burbidge Subject: AeroElectric-List: Master/Battery/Alt Field vs. Master/Battery and Alt Field... I'm sure I read a discussion of this question somewhere but can't find it. I'm building an RV-9A, basic day/night VFR. I'm using the Basic Day/Night VFR system diagram available from B&C website. It is almost identical to the Z-11 diagram in Bob's book. One difference is that the Z-11 uses a 2 poll 3-throw switch (2-10) for the master, so that the alternator can be switched on after start. The Basic VFR diagram from B&C uses a 2 poll 2 throw switch (2-3) so that the alternator field is on duri ng start. What are the advantages of isolating the alternator field during startup? My airplane has a B&C 40 amp alternator. Which approach would you recommend? Thanks, Michael- ________________________________ Message 7 _____________________________________ Time: 02:48:19 PM PST US Subject: AeroElectric-List: Low voltage indicator with dual alternators From: "donjohnston" I'm going to have a 60a primary and a 20a secondary alternator with B&C LR3C and LS1A voltage regulators respectively. If in the event of a primary alternator failure, and I switch to the secondary, will the primary low voltage warning light (off of LR3C, pin 5) remain illuminated? Or will switching off that alternator open the low voltage circuit? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=403960#403960 _____________ ___________________ Message 8 _____________________________________ Time: 02:57:44 PM PST US From: Bill Putney Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector It's TED 9-30-10 connector. These are solder on connectors and have the lowest profile (depth-wise). http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html You should check with them to make sure a snap ring is included or you may have to buy it separately. There's also a DBA-600 that is a connector like you want with a female BNC so you don't have a cable attached to your tray. You put a BNC on the cable and connect it to this adapter. About the same price as the 9-30-10 but of course you have to do the BNC too. http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSnap-Ring.html Bill On 7/4/13 10:59 AM, berkut13@berkut13.com wrote: > Can someone po int me to the part number/source for a replacement > 90-degree, > bulkhead, slide-on, coax connector used on the Narco AT-150 transponder > tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry > them? > > Thanks, > James > * > > > * ________________________________ Message 9 _____________________________________ Time: 03:22:42 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Re: Boeing switches At 01:05 PM 7/4/2013, you wrote: > >Good argument Bob.... I use a switch on the panel to power the trim, but >that may be a bit far away for a quick reaction, before the trim lurks all >the way to the end. You would do well to deduce the severity of a trim runaway. Is the airplane controllable with full trim either up or down? How fast does the trim run with respect to pilot reaction times needed to deal with a runaway? Are there stops or limits to trim excursion necessary for the full range of CG envelopes or will the system produce more pitch authority than would ever be necessary for normal operations? In a Lear, at Mach cruise, the system is manually failed and the pilot is obligated to keep hands in the lap for 3 seconds. Only then can he move to deal with the situation. After achieving a stable, safe condition, recorded data is analyzed for busting limits on attitude, altitude and airspeed excursions. The exercise is repeated and trim speeds then adjusted until a sweat-free, runaway recovery is assured. The trim systems I've seen in some TC aircraft a re so slow that unexpected trims under worst case conditions are no big deal. But what's the story for YOUR airplane? Yes, if trim speeds are brisk, trim authority high and you have good reason for not reducing them, then some form of inarguable override is indicated. Instructing the pilot to pull a breaker for taming a trim runaway is generally not acceptable . . . even panel mounted switche situated amongst other switches will get you frowns from the human factors guys. At the same time, find out just how much risk is associated with an uncontrolled trim event and see if that can be engineered out as opposed to stacking emergency ops hardware on top of the design. Bob . . . ________________________________ Message 10 ____________________________________ Time: 03:42:25 PM PST US From: Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector Excellent! Exactly what I needed. Thanks. From: Bill Putney Sent: Thursday, July 04, 2013 4:57 PM Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector It's TED 9-30-10 connector. These are solder on connectors and have the lowest profile (depth-wise). http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html You should check with them to make sure a snap ring is included or you may have to buy it separately. There's also a DBA-600 that is a connector like you want with a female BNC so you don't have a cable attached to your tray. You put a BNC on the cable and connect it to this adapter. About the same price as the 9-30-10 but of course you have to do the BNC too. http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSna ________________________________ Message 6 _____________________________________ Time: 10:50:23 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: solenoid wiring question At 11:28 AM 7/5/2013, you wrote: >Re figure 5 of Bob's diagram of adding a starter contactor upstream >of the original starter solenoid: Just so I'm clear, what "figure 5" are you referring to? Wired like this? Emacs! > >Is there any reason not to wire the fat wire to the starter side of >the old original starter solenoid, with a jumper from the fat wire >terminal back to the old starter solenoid energizer terminal. It would be helpful if you would sketch your proposed change, scan and attach to your email. > >The point would be to eliminate the high current having to flow >through the old starter solenoid disc, since the high current is >being controlled by the new upstream starter contactor. By 'original' I presume you're talking about the one built onto the starter. I'm not sure of "the point". Keep in mind that the solenoid/contactor combo on the starter has two jobs . . . extend pinion gear then apply power to motor. On the release side, power is first removed from the motor before the pinion gear is retracted. The reason for the upstream contactor is to buffer the current draw on the starter engage switch. An alternative method calls for a relay wired thusly. Emacs! Which ever way you decide to do it, the singular design goal is to reduce stresses on the starter engage switch on the panel. Bob . . . ________________________________ Message 7 _____________________________________ Time: 10:54:21 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Master/Battery/Alt Field vs. Master/Battery and Alt Field... At 11:34 AM 7/5/2013, you wrote: > >I'm using the LR3C-14 external regulator and fuse blocks from B&C. >My field supply includes a fuse in my fuse block but I cannot pull >the fuse during flight. then you have not followed instructions for the LR3C-14 for supplying field power through a breaker. This is to accommodate the regulator's built in crowbar OV shutdown system. >It sounds like I should either move the field supply to a breaker on >the panel that I can pull, or use the 3-position switch. You need the breaker anyhow. After that, a 2 or 3 position switch as you wish. >Another question. All of my 250 hours of flight are in a 1959 C172, >which has a generator. There is a master switch with two positions. >My question is under what conditions would one operate "battery only"? Ground maintenance operations. Getting the ATIS and Clearance delivery before starting the engine. Shutting the generator/alternator off for some kind of mis-behavior - voltage jumping around but not so vigorously as to trip the OV system. Bob . . . ________________________________ Message 8 _____________________________________ Time: 11:28:43 AM PST US From: Ed Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions So....on the SkyTec permanent magnet starter, the diode goes from the little terminal to where - ground on the starter case? By the way, I only measure approximately .3 ohms from the small terminal to the starter case. I thought the coil would have more resistance than that. The starter comes from SkyTec with a jumper from small terminal to the fat wire terminal. Ed Holyoke On 7/4/2013 6:18 AM, Robert L. Nuckolls, III wrote: > If the starter is a PM version, the builder can > take advantage of the "I" terminal on many modern > starter cotactors and use it to SUPPLY current > to the engagement solenoid. This provides for > instant removal of coil power when the starter > switch is opened and prevents 'delayed disengagement'. > > In this case, the builder would do well to have > diode coil suppression on BOTH the external contactor > coil AND the solenoid/contactor coil on the > starter. > > Bob . . . ________________________________ Message 9 _____________________________________ Time: 11:28:43 AM PST US Subject: Re: AeroElectric-List: Master/Battery/Alt Field vs. Master/Battery and Alt Field... From: Michael Burbidge Bob, Thanks. Glad I asked. I see the note about the breaker in bold. I had read the instructions at one point, and had ordered the 5 Amp breaker. So I have it. But I had not revisited the instructions when I started the wiring. It seems like a lot of non-TSO'ed equipment comes with almost no instructions and you get used to figuring it out on your own with help from forums and mailing lists. The B&C instructions are quite complete. A good reminder for me to use the instructions when they are supplied! Thanks, Michael- On Jul 5, 2013, at 10:53 AM, "Robert L. Nuckolls, III" wrote: > > At 11:34 AM 7/5/2013, you wrote: >> >> I'm using the LR3C-14 external regulator and fuse blocks from B&C. My field supply includes a fuse in my fuse block but I cannot pull the fuse during flight. > > then you have not followed instructions for the LR3C-14 > for supplying field power through a breaker. This is to > accommodate the regulator's built in crowbar OV shutdown > system. > >> It sounds like I should either move the field supply to a breaker on the panel that I can pull, or use the 3-position switch. > > You need the breaker anyhow. After that, a 2 or 3 position > switch as you wish. > >> Another question. All of my 250 hours of flight are in a 1959 C172, which has a generator. There is a master switch with two positions. My question is under what conditions would one operate "battery only"? > > Ground maintenance operations. Getting the > ATIS and Clearance delivery before starting > the engine. Shutting the generator/alternator > off for some kind of mis-behavior - voltage jumping > around but not so vigorously as to trip the OV > system. > > > Bob . . . > > > > ________________________________ Message 10 ____________________________________ Time: 11:34:24 AM PST US Subject: AeroElectric-List: Re: Low voltage indicator with dual alternators From: "donjohnston" nuckolls.bob(at)aeroelect wrote: > At 04:47 PM 7/4/2013, you wrote: > > > > > > > I'm going to have a 60a primary and a 20a secondary alternator with > > B&C LR3C and LS1A voltage regulators respectively. > > > > If in the event of a primary alternator failure, and I switch to the > > secondary, will the primary low voltage warning light (off of LR3C, > > pin 5) remain illuminated? Or will switching off that alternator > > open the low voltage circuit? > > > > > > No, the OV and LV sense lines along with power to > run those systems is independent of the regulator > circuits. The LV warning systems will function whether > or not the alternator is powered. > > Bob . . . Sorry if I'm belaboring the point, I just want to make sure I got this right. If I switch to the secondary alternator (and switch off the primary alternator), the LV light on the primary's VR will not be illuminated? -Don Read this topic online here: http://forums.matronics.com/viewtopic.php?p=403999#403999 ________________________________ Message 11 ____________________________________ Time: 11:59:35 AM PST US From: Bill Putney Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions Ed, Do you get the same resistance reading in both directions? What if you swap your meter leads? If there's an internal snubbing diode there, you'll get a really low resistance reading in the direction the diode conducts in and you'll read the coil resistance with the meter leads swapped the other way around. .3 ohms at 14V would pull about 47 amps. Probably more than your starter switch can handle. I'm thinking it should be like 30 ohms or more. Bill On 7/5/13 11:28 AM, Ed wrote: > > So....on the SkyTec permanent magnet starter, the diode goes from the > little terminal to where - ground on the starter case? By the way, I > only measure approximately .3 ohms from the small terminal to the > starter case. I thought the coil would have more resistance than that. > The starter comes from SkyTec with a jumper from small terminal to the > fat wire terminal. > > Ed Holyoke > > > On 7/4/2013 6:18 AM, Robert L. Nuckolls, III wrote: >> If the starter is a PM version, the builder can >> take advantage of the "I" terminal on many modern >> starter cotactors and use it to SUPPLY current >> to the engagement solenoid. This provides for >> instant removal of coil power when the starter >> switch is opened and prevents 'delayed disengagement'. >> >> In this case, the builder would do well to have >> diode coil suppression on BOTH the external contactor >> coil AND the solenoid/contactor coil on the >> starter. >> >> Bob . . . > > ________________________________ Message 12 ____________________________________ Time: 12:25:47 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions At 01:28 PM 7/5/2013, you wrote: > >So....on the SkyTec permanent magnet starter, the diode goes from >the little terminal to where - ground on the starter case? Same for ALL starters with the built in solenoid/contactor. Emacs! .... or like this Emacs! > By the way, I only measure approximately .3 ohms from the small > terminal to the starter case. I thought the coil would have more > resistance than that. The starter comes from SkyTec with a jumper > from small terminal to the fat wire terminal. Yup, that resistance to ground is LOW . . . it gets higher after the pinion gear extends but the initial current draw is significant. That's why you use external contactors or a buffer relay as shown above . . . I've added diodes to Z22 . . . something I should have done years ago. Thanks for reminding me. Bob . . . ________________________________ Message 13 ____________________________________ Time: 12:27:44 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Low voltage indicator with dual alternators At 01:33 PM 7/5/2013, you wrote: > > >nuckolls.bob(at)aeroelect wrote: > > At 04:47 PM 7/4/2013, you wrote: > > > > > > > > > > > I'm going to have a 60a primary and a 20a secondary alternator with > > > B&C LR3C and LS1A voltage regulators respectively. > > > > > > If in the event of a primary alternator failure, and I switch to the > > > secondary, will the primary low voltage warning light (off of LR3C, > > > pin 5) remain illuminated? Or will switching off that alternator > > > open the low voltage circuit? > > > > > > > > > > No, the OV and LV sense lines along with power to > > run those systems is independent of the regulator > > circuits. The LV warning systems will function whether > > or not the alternator is powered. > > > > Bob . . . > > >Sorry if I'm belaboring the point, I just want to make sure I got this right. > >If I switch to the secondary alternator (and switch off the primary >alternator), the LV light on the primary's VR will not be illuminated? > >-Don I presume you're talking about Z-12. Any time you have a low voltage condition, both regulators will flash their low voltage lights (if installed). Since lv warning is redundant, you COULD install only one light on either one of the regulators. Bob . . . ________________________________ Message 14 ____________________________________ Time: 12:29:16 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions At 01:58 PM 7/5/2013, you wrote: > >Ed, > >Do you get the same resistance reading in both directions? What if >you swap your meter leads? If there's an internal snubbing diode >there, you'll get a really low resistance reading in the direction >the diode conducts in and you'll read the coil resistance with the >meter leads swapped the other way around. > >.3 ohms at 14V would pull about 47 amps. Probably more than your >starter switch can handle. I'm thinking it should be like 30 ohms or more. > >Bill 40 amps . . . yeah that's about right. See: http://tinyurl.com/op5cs2g Bob . . . ________________________________ Message 15 ____________________________________ Time: 02:16:14 PM PST US From: Bill Watson Subject: Re: AeroElectric-List: Low voltage indicator with dual alternators On 7/5/2013 9:05 AM, Robert L. Nuckolls, III wrote: > > > At 04:47 PM 7/4/2013, you wrote: >> >> I'm going to have a 60a primary and a 20a secondary alternator with >> B&C LR3C and LS1A voltage regulators respectively. >> >> If in the event of a primary alternator failure, and I switch to the >> secondary, will the primary low voltage warning light (off of LR3C, >> pin 5) remain illuminated? Or will switching off that alternator open >> the low voltage circuit? > > No, the OV and LV sense lines along with power to > run those systems is independent of the regulator > circuits. The LV warning systems will function whether > or not the alternator is powered. I have the same setup and that's how it works. That is, the low voltage light simply monitors the voltage on the buss independent of alternator operation. Given that, I've wondered how a failed alternator would manifest itself. - If failure was due to an overvoltage situation, the breaker would pop. Since I normally fly with the 2 busses interconnected, I would expect the low voltage lights to remain off perhaps for the remainder of the flight. If one did come on because buss voltage dropped below the threshold, I would expect both to come on more or less simultaneously as long as the busses were interconnected. The only explicit indication of Alt failure would be the popped OV breaker. - Are there other modes of Alternator failure where there would be no explicit indication of failure? I'm thinking that a snapped belt would be an example. If loads and battery condition were such that the interconnected buss voltage stayed above the low volt threshold, there would be no explicit indication. Is that right? ________________________________ Message 16 ____________________________________ Time: 02:27:37 PM PST US From: cardinalnsb Subject: AeroElectric-List: solenoid wiring question My previous question referenced figure 5 of Bob's diagram, it should have referenced figure 6. Corrected below. Re figure 6 of Bob's diagram of adding a starter contactor upstream of the original starter solenoid: Is there any reason not to wire the fat wire to the starter side of the old original starter solenoid, with a jumper from the fat wire terminal back to the old starter solenoid energizer terminal. The point would be to eliminate the high current having to flow through the old starter solenoid disc, since the high current is being controlled by the new upstream starter contactor. Thanks, Skip Simpson In a message dated 07/05/13 03:12:33 Eastern Daylight Time, aeroelectric-list@matronics.com writes: * ================================================== Online Versions of Today's List Digest Archive ================================================== Today's complete AeroElectric-List Digest can also be found in either of the two Web Links listed below. The .html file includes the Digest formatted in HTML for viewing with a web browser and features Hyperlinked Indexes and Message Navigation. The .txt file includes the plain ASCII version of the AeroElectric-List Digest and can be viewed with a generic text editor such as Notepad or with a web browser. HTML Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter 13-07-04&Archive=AeroElectric Text Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter 13-07-04&Archive=AeroElectric ================================================ EMail Version of Today's List Digest Archive ================================================ ---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 07/04/13: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:32 AM - Re: Boeing switches (Eric M. Jones) 2. 06:20 AM - Re: Re: Master Switch/Contactor and Starter Questions (Robert L. Nuckolls, III) 3. 07:29 AM - Re: Re: Boeing switches (Robert L. Nuckolls, III) 4. 11:00 AM - Narco Transponder Tray Coax Connector () 5. 11:05 AM - Re: Re: Boeing switches (Jay Hyde) 6. 12:17 PM - Master/Battery/Alt Field vs. Master/Battery and Alt Field... (Michael Burbidge) 7. 02:48 PM - Low voltage indicator with dual alternators (donjohnston) 8. 02:57 PM - Re: Narco Transponder Tray Coax Connector (Bill Putney) 9. 03:22 PM - Re: Re: Boeing switches (Robert L. Nuckolls, III) 10. 03:42 PM - Re: Narco Transponder Tray Coax Connector () ________________________________ Message 1 _____________________________________ Time: 05:32:21 AM PST US Subject: AeroElectric-List: Re: Boeing switches From: "Eric M. Jones" My two cents: Using two parallel switches to prevent trim runaway seems boneheaded, and wouldn't stand a thorough engineering fault-tree review. Furthermore I'd bet that it never prevented ANY problem from occurring. Sure, I understand the intention, but I don't think it's good engineering. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=403912#403912 ________________________________ Message 2 _____________________________________ Time: 06:20:29 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions At 07:13 PM 7/3/2013, you wrote: > > >I agree. It seems pointless to have 2 solenoids operating at the >same time. The other issue is that I believe the Subaru solenoid >moves the gear before the contactor part puts juice to the motor >brushes. An aircraft type contactor would do both at the same time >rather than sequentially. Have not dismantled one so I may be in error. None of applications of an external contactor proposed for modern starters "bypasses" functionality of the built in solenoid/contactor. The starter's built in solenoids do engage the pinion gear before closing electrical connection for the starter motor. Variants to select from when using these modern starters causes the builder to decide whether the built in contactor is energized by the panel mounted, START switch -OR- energized through a more robust device. There is a problem to be solved when the panel mounted starter control is used to energize the starter's built in contactor. Unlike legacy 'starter solenoids' controlling starters with Bendix drives, the modern pinion engagement solenoids have a very high coil current demand during the first few milliseconds of being energized. See: http://tinyurl.com/op5cs2g Failure to recognize this difference in solenoid/contator performance caused a kerfuffle over burned start switch contacts on the ACS-510 key swicch (clone of legacy Bendix/Gerdes). ACS now sells a diode with two terminals applied. Emacs! A critical need to install this diode across the starter contactor engagement coil arose from the alarming rate at which start contacts in the key switch were destroyed by overstress when the legacy starter/external contactor combo was replaced with a light weight version with combination solenoid/ contactors. Many cars suffered similar failure modes in their key-start switches. SB92-01 from ACS originally place thier diode across the switch contacts . . . wrong place. It was corrected in a subsequent revision. See http://tinyurl.com/nva2xdy B&C adopted the philosophy of jumpering the starter solenoid coil right to the fat-wire terminal on the starter . . . and controlling power to the starter though a modern, starter contactor WITH built in coil suppression diode. The external contactor's inrush demands on the start switch are a small fraction of that for direct control. This philosophy posed a new problem when PM motor starters began to show up on the airplane. PM motors have a pronounced counter-emf during spin-down after the power is removed. This would delay disengagement of the pinion gear and was commonly called "starter run on" . . . in fact it was better called "delayed disengagement". Starters with wound fields (B&C and some others) do not suffer this indignity and function well with the engagement solenoid jumpered directly to the starter's fat-wire terminal. In ANY case, the builder's design goals should include providing a source of solenoid engagement power that (1) is supplied through a low impedance source (short and fatter than usual wires) and (2) avoid running this power through the panel mounted start switch. If the starter is a PM version, the builder can take advantage of the "I" terminal on many modern starter cotactors and use it to SUPPLY current to the engagement solenoid. This provides for instant removal of coil power when the starter switch is opened and prevents 'delayed disengagement'. In this case, the builder would do well to have diode coil suppression on BOTH the external contactor coil AND the solenoid/contactor coil on the starter. Bob . . . ________________________________ Message 3 _____________________________________ Time: 07:29:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Boeing switches At 07:29 AM 7/4/2013, you wrote: > >My two cents: > >Using two parallel switches to prevent trim runaway seems >boneheaded, and wouldn't stand a thorough engineering fault-tree >review. Furthermore I'd bet that it never prevented ANY problem from occurring. Whether or not a problem was demonstrably prevented is irrelevant to the reliability study. Good FMEA mitigation assumes that the part WILL fail. Working out a logical means by which single failures might go undetected for no more than a single tank full of fuel has been a time-honored legacy design goal. >Sure, I understand the intention, but I don't think it's good engineering. they are not used in PARALLEL. In the Boeing case, they are in series with one side controlling direction, the other side in SERIES controlling power. Each side can be explored for functionality in pre-flight, neither side capable of causing a runaway-by-sticking. Beech (and many others) uses the two spdt switches to handle one half of a PM motor UP-OFF- DN switching duty. Again, both sides easily evaluated in pre-flight, neither side capable of causing a runaway-by-sticking. Lear (and many others) uses the 'coolie hat' to drive relays that DID offer a possibility for runaway-by- sticking. But their systems architecture included a wheel-master-disconnect that removed power from all trim systems along with the autopilot. I AM aware of trim runaways in aircraft fitted with wheel master disconnects that would not have happened if the airplane had been fitted with the split trim switch where the WMD switch provided the mitigation. Bob . . . ________________________________ Message 4 _____________________________________ Time: 11:00:48 AM PST US From: Subject: AeroElectric-List: Narco Transponder Tray Coax Connector Can someone point me to the part number/source for a replacement 90-degree, bulkhead, slide-on, coax connector used on the Narco AT-150 transponder tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry them? Thanks, James ________________________________ Message 5 _____________________________________ Time: 11:05:43 AM PST US From: "Jay Hyde" Subject: RE: AeroElectric-List: Re: Boeing switches Good argument Bob.... I use a switch on the panel to power the trim, but that may be a bit far away for a quick reaction, before the trim lurks all the way to the end. Jay -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: 04 July 2013 04:29 PM Subject: Re: AeroElectric-List: Re: Boeing switches --> At 07:29 AM 7/4/2013, you wrote: >--> > >My two cents: > >Using two parallel switches to prevent trim runaway seems boneheaded, >and wouldn't stand a thorough engineering fault-tree review. >Furthermore I'd bet that it never prevented ANY problem from occurring. Whether or not a problem was demonstrably prevented is irrelevant to the reliability study. Good FMEA mitigation assumes that the part WILL fail. Working out a logical means by which single failures might go undetected for no more than a single tank full of fuel has been a time-honored legacy design goal. >Sure, I understand the intention, but I don't think it's good engineering. they are not used in PARALLEL. In the Boeing case, they are in series with one side controlling direction, the other side in SERIES controlling power. Each side can be explored for functionality in pre-flight, neither side capable of causing a runaway-by-sticking. Beech (and many others) uses the two spdt switches to handle one half of a PM motor UP-OFF- DN switching duty. Again, both sides easily evaluated in pre-flight, neither side capable of causing a runaway-by-sticking. Lear (and many others) uses the 'coolie hat' to drive relays that DID offer a possibility for runaway-by- sticking. But their systems architecture included a wheel-master-disconnect that removed power from all trim systems along with the autopilot. I AM aware of trim runaways in aircraft fitted with wheel master disconnects that would not have happened if the airplane had been fitted with the split trim switch where the WMD switch provided the mitigation. Bob . . . ________________________________ Message 6 _____________________________________ Time: 12:17:10 PM PST US From: Michael Burbidge Subject: AeroElectric-List: Master/Battery/Alt Field vs. Master/Battery and Alt Field... I'm sure I read a discussion of this question somewhere but can't find it. I'm building an RV-9A, basic day/night VFR. I'm using the Basic Day/Night VFR system diagram available from B&C website. It is almost identical to the Z-11 diagram in Bob's book. One difference is that the Z-11 uses a 2 poll 3-throw switch (2-10) for the master, so that the alternator can be switched on after start. The Basic VFR diagram from B&C uses a 2 poll 2 throw switch (2-3) so that the alternator field is on during start. What are the advantages of isolating the alternator field during startup? My airplane has a B&C 40 amp alternator. Which approach would you recommend? Thanks, Michael- ________________________________ Message 7 _____________________________________ Time: 02:48:19 PM PST US Subject: AeroElectric-List: Low voltage indicator with dual alternators From: "donjohnston" I'm going to have a 60a primary and a 20a secondary alternator with B&C LR3C and LS1A voltage regulators respectively. If in the event of a primary alternator failure, and I switch to the secondary, will the primary low voltage warning light (off of LR3C, pin 5) remain illuminated? Or will switching off that alternator open the low voltage circuit? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=403960#403960 ________________________________ Message 8 _____________________________________ Time: 02:57:44 PM PST US From: Bill Putney Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector It's TED 9-30-10 connector. These are solder on connectors and have the lowest profile (depth-wise). http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html You should check with them to make sure a snap ring is included or you may have to buy it separately. There's also a DBA-600 that is a connector like you want with a female BNC so you don't have a cable attached to your tray. You put a BNC on the cable and connect it to this adapter. About the same price as the 9-30-10 but of course you have to do the BNC too. http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSnap-Ring.html Bill On 7/4/13 10:59 AM, berkut13@berkut13.com wrote: > Can someone point me to the part number/source for a replacement > 90-degree, > bulkhead, slide-on, coax connector used on the Narco AT-150 transponder > tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry > them? > > Thanks, > James > * > > > * ________________________________ Message 9 _____________________________________ Time: 03:22:42 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Re: Boeing switches At 01:05 PM 7/4/2013, you wrote: > >Good argument Bob.... I use a switch on the panel to power the trim, but >that may be a bit far away for a quick reaction, before the trim lurks all >the way to the end. You would do well to deduce the severity of a trim runaway. Is the airplane controllable with full trim either up or down? How fast does the trim run with respect to pilot reaction times needed to deal with a runaway? Are there stops or limits to trim excursion necessary for the full range of CG envelopes or will the system produce more pitch authority than would ever be necessary for normal operations? In a Lear, at Mach cruise, the system is manually failed and the pilot is obligated to keep hands in the lap for 3 seconds. Only then can he move to deal with the situation. After achieving a stable, safe condition, recorded data is analyzed for busting limits on attitude, altitude and airspeed excursions. The exercise is repeated and trim speeds then adjusted until a sweat-free, runaway recovery is assured. The trim systems I've seen in some TC aircraft are so slow that unexpected trims under worst case conditions are no big deal. But what's the story for YOUR airplane? Yes, if trim speeds are brisk, trim authority high and you have good reason for not reducing them, then some form of inarguable override is indicated. Instructing the pilot to pull a breaker for taming a trim runaway is generally not acceptable . . . even panel mounted switche situated amongst other switches will get you frowns from the human factors guys. At the same time, find out just how much risk is associated with an uncontrolled trim event and see if that can be engineered out as opposed to stacking emergency ops hardware on top of the design. Bob . . . ________________________________ Message 10 ____________________________________ Time: 03:42:25 PM PST US From: Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector Excellent! Exactly what I needed. Thanks. From: Bill Putney Sent: Thursday, July 04, 2013 4:57 PM Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector It's TED 9-30-10 connector. These are solder on connectors and have the lowest profile (depth-wise). http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html You should check with them to make sure a snap ring is included or you may have to buy it separately. There's also a DBA-600 that is a connector like you want with a female BNC so you don't have a cable attached to your tray. You put a BNC on the cable and connect it to this adapter. About the same price as the 9-30-10 but of course you have to do the BNC too. http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSnap-Ring.html Bill On 7/4/13 10:59 AM, berkut13@berkut13.com wrote: Can someone point me to the part number/source for a replacement 90-degree, bulkhead, slide-on, coax connector used on the Narco AT-150 transponder tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) carry them? Thanks, James ________________________________ Message 17 ____________________________________ Time: 07:52:47 PM PST US Subject: AeroElectric-List: Re: Master/Battery/Alt Field vs. Master/Battery and Alt Field... From: "user9253" > One difference is that the Z-11 uses a 2 poll 3-throw switch (2-10) for the master, so that the alternator can be switched on after start. Wired per Z-11, the alternator could be switched off during start, but I do not think that is the intent or common usage. I would start the engine with the alternator field turned on. There are some situations when it is desirable to shut the alternator field off. One situation is parked on the ground with the engine off and battery contactor on. Another situation is when the charging system malfunctions in the air. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=404021#404021 ________________________________ Message 18 ____________________________________ Time: 09:29:39 PM PST US From: Ed Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions ________________________________ Message 19 ____________________________________ Time: 09:55:42 PM PST US From: Ed Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and Starter Questions I knew on some level that low ohms means high current. That's why I questioned it, but I didn't do the math. 35 amps is a bunch! I'm not planning to throw away my starter contactor anytime soon. I did measure the coil both directions and it is the same. Ed Holyoke On 7/5/2013 12:29 PM, Robert L. Nuckolls, III wrote: > > > At 01:58 PM 7/5/2013, you wrote: >> >> Ed, >> >> Do you get the same resistance reading in both directions? What if >> you swap your meter leads? If there's an internal snubbing diode >> there, you'll get a really low resistance reading in the direction >> the diode conducts in and you'll read the coil resistance with the >> meter leads swapped the other way around. >> >> .3 ohms at 14V would pull about 47 amps. Probably more than your >> starter switch can handle. I'm thinking it should be like 30 ohms or >> more. >> >> Bill > > 40 amps . . . yeah that's about right. > See: > > http://tinyurl.com/op5cs2g > > > Bob . . . > > ________________________________ Message 20 ____________________________________ Time: 10:08:25 PM PST US From: Ed Subject: Re: AeroElectric-List: solenoid wiring question Skip, If I read you right, you are talking about bypassing the solenoid on the starter and wiring straight to the starter motor terminal. What then pulls the pinion gear forward to engage with the ring gear? The solenoid normally does that before the starter motor starts to spin. As the gear shaft bottoms, the contacts in the solenoid power up the motor. Even if the solenoid coil is backfed from the motor terminal and pulls the pinion gear up, the motor will already be spinning full bore. I'm guessing that chipped teeth on the ring gear are in your future. I'd wire it as Bob drew it. Ed Holyoke On 7/5/2013 2:26 PM, cardinalnsb wrote: > My previous question referenced figure 5 of Bob's diagram, it should > have referenced figure 6. Corrected below. > Re figure 6 of Bob's diagram of adding a starter contactor upstream of > the original starter solenoid: > Is there any reason not to wire the fat wire to the starter side of > the old original starter solenoid, with a jumper from the fat wire > terminal back to the old starter solenoid energizer terminal. > The point would be to eliminate the high current having to flow > through the old starter solenoid disc, since the high current is being > controlled by the new upstream starter contactor. > Thanks, Skip Simpson > In a message dated 07/05/13 03:12:33 Eastern Daylight Time, > aeroelectric-list@matronics.com writes: > > * > > ================================================= > Online Versions of Today's List Digest Archive > ================================================= > > Today's complete AeroElectric-List Digest can also be found in > either of the > two Web Links listed below. The .html file includes the Digest > formatted > in HTML for viewing with a web browser and features Hyperlinked > Indexes > and Message Navigation. The .txt file includes the plain ASCII > version > of the AeroElectric-List Digest and can be viewed with a generic > text editor > such as Notepad or with a web browser. > > HTML Version: > > http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter 13-07-04&Archive=AeroElectric > > > Text Version: > > http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter 13-07-04&Archive=AeroElectric > > > ============================ =================== > EMail Version of Today's List Digest Archive > =============================================== > > > ---------------------------------------------------------- > AeroElectric-List Digest Archive > --- > Total Messages Posted Thu 07/04/13: 10 > ---------------------------------------------------------- > > > Today's Message Index: > ---------------------- > > 1. 05:32 AM - Re: Boeing switches (Eric M. Jones) > 2. 06:20 AM - Re: Re: Master Switch/Contactor and Starter > Questions (Robert L. Nuckolls, III) > ; 3. 07:29 AM - Re: Re: Boeing switches (Robert L. Nuckolls, > III) > 4. 11:00 AM - Narco Transponder Tray Coax Connector () > 5. 11:05 AM - Re: Re: Boeing switches (Jay Hyde) > 6. 12:17 PM - Master/Battery/Alt Field vs. Master/Battery and > Alt Field... (Michael Burbidge) > 7. 02:48 PM - Low voltage indicator with dual alternators > (donjohnston) > 8. 02:57 PM - Re: Narco Transponder Tray Coax Connector (Bill > Putney) > 9. 03:22 PM - Re: Re: Boeing switches (Robert L. Nuckolls, III) > 10. 03:42 PM - Re: Narco Transponder Tray Coax Connector () > > > ________________________________ Message 1 > _____________________________________ > > > Time: 05:32:21 AM PST US > Subject: AeroElectric-List: Re: Boeing switches > From: "Eric M. Jones" > > > My two cents: > > Using two parallel switches to prevent trim runaway seems > boneheaded, and wouldn't > stand a thorough engineering fault-tree review. Furthermore I'd > bet that it > never prevented ANY problem from occurring. > > Sure, I understand the intention, but I don't think it's good > engineering. > > -------- > Eric M. Jones > www.PerihelionDesign.com > 113 Brentwood Drive > Southbridge, MA 01550 > (508) 764-2072 > emjones(at)charter.net > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=403912#403912 > > > ________________________________ Message 2 > _____________________________________ > > > Time: 06:20:29 AM PST US > From: "Robert L. Nuckolls, III" > Subject: Re: AeroElectric-List: Re: Master Switch/Contactor and > Starter Questions > > At 07:13 PM 7/3/2013, you wrote: > > > > > >I agree. It se ems pointless to have 2 solenoids operating at the > >same time. The other issue is that I believe the Subaru solenoid > >moves the gear before the contactor part puts juice to the motor > >brushes. An aircraft type contactor would do both at the same time > >rather than sequentially. Have not dismantled one so I may be in > error. > > None of applications of an external contactor > proposed for modern starters "bypasses" functionality > of the built in solenoid/contactor. The > starter's built in solenoids do engage the pinion > gear before closing electrical connection for > the starter motor. > > Variants to select from when using these modern > starters causes the builder to decide whether > the built in contactor is energized by the panel > mounted, START switch -OR- energized through a more > robust device. > > There is a problem to be solved when the panel > mounted starter control is used to energize the > starter's built in contactor. Unlike legacy > 'starter solenoids' controlling starters with > Bendix drives, the modern pinion engagement > solenoids have a very high coil current demand > during the first few milliseconds of being > energized. See: http://tinyurl.com/op5cs2g > > Failure to recognize this difference in > solenoid/contator performance caused a > kerfuffle over burned start switch contacts > on the ACS-510 key swicch (clone of legacy > Bendix/Gerdes). ACS now sells a diode with two > terminals applied. > > Emacs! > > > A critical need to install this diode across the > starter contactor engagement coil arose from the > alarming rate at which start contacts in the key > switch were destroyed by overstress when the legacy > starter/external contactor combo was replaced with > a light weight version with combination solenoid/ > contactors. Many cars suffered similar failure modes > in their key-start switches. > > SB92-01 from ACS originally place thier diode across > the switch contacts . . . wrong place. It was corrected > in a subsequent revision. See http://tinyurl.com/nva2xdy > > B&C adopted the philosophy of jumpering the starter > solenoid coil right to the fat-wire terminal on > the starter . . . and controlling power to the > starter though a modern, starter contactor WITH > built in coil suppression diode. The external contactor's > inrush demands on the start switch are a small fraction > of that for direct control. > > This philosophy posed a new problem when PM motor > starters began to show up on the airplane. PM motors > have a pronounced counter-emf during spin-down after > the power is removed. This would delay disengagement > of the pinion gear and was commonly called "starter > run on" . . . in fact it was better called "delayed > disengagement". > > Starters with wound fields (B&C and some others) > do not suffer this indignity and function well with > the engagement solenoid jumpered directly to the > starter's fat-wire terminal. > > In ANY case, the builder's design goals should > include providing a source of solenoid engagement > power that (1) is supplied through a low impedance > source (short and fatter than usual wires) and > (2) avoid running this power through the panel > mounted start switch. > > If the starter is a PM version, the builder can > take advantage of the "I" terminal on many modern > starter cotactors and use it to SUPPLY current > to the engagement solenoid. This provides for > instant removal of coil power when the starter > switch is opened and prevents 'delayed disengagement'. > > In this case, the builder would do well to have > diode coil suppression on BOTH the external contactor > coil AND the solenoid/contactor coil on the > starter. > > Bob . . . > > ________________________________ Message 3 > _____________________________________ > > > Time: 07:29:28 AM PST US > From: "Robert L. Nuckolls, III" > Subject: Re: AeroElectric-List: Re: Boeing switches > > > At 07:29 AM 7/4/2013, you wrote: > > > >My two cents: > > > >Using two parallel switches to prevent trim runaway seems > >boneheaded, and wouldn't stand a thorough engineering fault-tree > >review. Furthermore I'd bet that it never prevented ANY problem > from occurring. > > Whether or not a problem was demonstrably > prevented is irrelevant to the reliability > study. Good FMEA mitigation assumes that the > part WILL fail. Working out a logical means > by which single failures might go undetected > for no more than a single tank full of fuel > has been a time-honored legacy design goal. > > >Sure, I understand the intention, but I don't think it's good > engineering. > > they are not used in PARALLEL. In the Boeing > case, they are in series with one side controlling > direction, the other side in SERIES controlling power. > Each side can be explored for functionality > in pre-flight, neither side capable of causing > a runaway-by-sticking. > > Beech (and many others) uses the two spdt > switches to handle one half of a PM motor UP-OFF- > DN switchin g duty. Again, both sides easily > evaluated in pre-flight, neither side capable > of causing a runaway-by-sticking. > > Lear (and many others) uses the 'coolie hat' to > drive relays that DID offer a possibility for runaway-by- > sticking. But their systems architecture included > a wheel-master-disconnect that removed power from > all trim systems along with the autopilot. I AM > aware of trim runaways in aircraft fitted with > wheel master disconnects that would not have happened > if the airplane had been fitted with the split > trim switch where the WMD switch provided the > mitigation. > > > Bob . . . > > > ________________________________ Message 4 > _____________________________________ > > > Time: 11:00:48 AM PST US > From: > Subject: AeroElectric-List: Narco Transponder Tray Coax Con nector > > Can someone point me to the part number/source for a replacement > 90-degree, > bulkhead, slide-on, coax connector used on the Narco AT-150 > transponder > tray? Any of the usual suspects (Mouser, Digi-Key, Allied, etc) > carry > them? > > Thanks, > James > > ________________________________ Message 5 > _____________________________________ > > > Time: 11:05:43 AM PST US > From: "Jay Hyde" > Subject: RE: AeroElectric-List: Re: Boeing switches > > > Good argument Bob.... I use a switch on the panel to power the > trim, but > that may be a bit far away for a quick reaction, before the trim > lurks all > the way to the end. > > Jay > > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of > Robert L. > Nuckolls, III > Sent: 04 July 2013 04:29 PM > Subject: Re: AeroElect ric-List: Re: Boeing switches > > --> > > At 07:29 AM 7/4/2013, you wrote: > >--> > > > >My two cents: > > > >Using two parallel switches to prevent trim runaway seems > boneheaded, > >and wouldn't stand a thorough engineering fault-tree review. > >Furthermore I'd bet that it never prevented ANY problem from > occurring. > > Whether or not a problem was demonstrably > prevented is irrelevant to the reliability > study. Good FMEA mitigation assumes that the > part WILL fail. Working out a logical means > by which single failures might go undetected > for no more than a single tank full of fuel > has been a time-honored legacy design goal. > > >Sure, I understand the intention, but I don't think it's good > engineering. > > they are not used in PARALLEL. In the Boeing > case, the y are in series with one side controlling > direction, the other side in SERIES controlling power. > Each side can be explored for functionality > in pre-flight, neither side capable of causing > a runaway-by-sticking. > > Beech (and many others) uses the two spdt > switches to handle one half of a PM motor UP-OFF- > DN switching duty. Again, both sides easily > evaluated in pre-flight, neither side capable > of causing a runaway-by-sticking. > > Lear (and many others) uses the 'coolie hat' to > drive relays that DID offer a possibility for runaway-by- > sticking. But their systems architecture included > a wheel-master-disconnect that removed power from > all trim systems along with the autopilot. I AM > aware of trim runaways in aircraft fitted with > wheel master disconnects that would not have happened > if the airplane had been fitted with the split > trim switch where the WMD switch provided the > mitigation. > > > Bob . . . > > > ________________________________ Message 6 > _____________________________________ > > > Time: 12:17:10 PM PST US > From: Michael Burbidge > Subject: AeroElectric-List: Master/Battery/Alt Field vs. > Master/Battery and Alt > Field... > > > I'm sure I read a discussion of this question somewhere but can't > find it. > > I'm building an RV-9A, basic day/night VFR. I'm using the Basic > Day/Night VFR system > diagram available from B&C website. It is almost identical to the > Z-11 diagram > in Bob's book. One difference is that the Z-11 uses a 2 poll > 3-throw switch > (2-10) for the master, so that the alternator can be switched on > after start. > The Basic VFR diagram from B&C uses a 2 poll 2 throw switch (2-3) > so that > the alternator field is on duri ng start. > > What are the advantages of isolating the alternator field during > startup? My airplane > has a B&C 40 amp alternator. Which approach would you recommend? > > Thanks, > Michael- > > > ________________________________ Message 7 > _____________________________________ > > > Time: 02:48:19 PM PST US > Subject: AeroElectric-List: Low voltage indicator with dual > alternators > From: "donjohnston" > > > I'm going to have a 60a primary and a 20a secondary alternator > with B&C LR3C and > LS1A voltage regulators respectively. > > If in the event of a primary alternator failure, and I switch to > the secondary, > will the primary low voltage warning light (off of LR3C, pin 5) > remain illuminated? > Or will switching off that alternator open the low voltage circuit? > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=403960#403960 > > > _____________ ___________________ Message 8 > _____________________________________ > > > Time: 02:57:44 PM PST US > From: Bill Putney > Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector > > It's TED 9-30-10 connector. These are solder on connectors and > have the > lowest profile (depth-wise). > > http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html > > You should check with them to make sure a snap ring is included or > you > may have to buy it separately. > > There's also a DBA-600 that is a connector like you want with a > female > BNC so you don't have a cable attached to your tray. You put a BNC on > the cable and connect it to this adapter. About the same price as the > 9-30-10 but of course you have to do the BNC too. > > http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSnap-Ring.html > > > Bill > > On 7/4/13 10:59 AM, berkut13@berkut13.com wrote: > > Can someone po int me to the part number/source for a replacement > > 90-degree, > > bulkhead, slide-on, coax connector used on the Narco AT-150 > transponder > > tray? Any of the usual suspects (Mouser, Digi-Key, Allied, > etc) carry > > them? > > > > Thanks, > > James > > * > > > > > > * > > > ________________________________ Message 9 > _____________________________________ > > > Time: 03:22:42 PM PST US > From: "Robert L. Nuckolls, III" > Subject: RE: AeroElectric-List: Re: Boeing switches > > > At 01:05 PM 7/4/2013, you wrote: > > > >Good argument Bob.... I use a switch on the panel to power the > trim, but > >that may be a bit far away for a quick reaction, before the trim > lurks all > >the way to the end. > > You would do well to deduce the severity of a > trim runaway. Is the airplane controllable with > full trim either up or down? How fast does the > trim run with respect to pilot reaction times > needed to deal with a runaway? Are there stops > or limits to trim excursion necessary for the full > range of CG envelopes or will the system produce > more pitch authority than would ever be necessary > for normal operations? > > In a Lear, at Mach cruise, the system is manually > failed and the pilot is obligated to keep hands in > the lap for 3 seconds. Only then can he move to > deal with the situation. After achieving a stable, > safe condition, recorded data is analyzed for > busting limits on attitude, altitude and airspeed > excursions. > > The exercise is repeated and trim speeds then > adjusted until a sweat-free, runaway recovery > is assured. > > The trim systems I've seen in some TC aircraft > a re so slow that unexpected trims under worst > case conditions are no big deal. But what's the > story for YOUR airplane? > > Yes, if trim speeds are brisk, trim authority high > and you have good reason for not reducing them, then some > form of inarguable override is indicated. Instructing > the pilot to pull a breaker for taming a trim runaway > is generally not acceptable . . . even panel mounted > switche situated amongst other switches will get > you frowns from the human factors guys. > > At the same time, find out just how much risk is > associated with an uncontrolled trim event and > see if that can be engineered out as opposed to > stacking emergency ops hardware on top of the > design. > > > Bob . . . > > > ________________________________ Message 10 > ____________________________________ > > > Time: 03:42:25 PM PST US > From: > Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector > > Excellent! Exactly what I needed. Thanks. > > > From: Bill Putney > Sent: Thursday, July 04, 2013 4:57 PM > Subject: Re: AeroElectric-List: Narco Transponder Tray Coax Connector > > It's TED 9-30-10 connector. These are solder on connectors and > have the > lowest profile (depth-wise). > > http://hangar-10.com/products/Tray-Mount-Rf-Antenna-Connect.html > > You should check with them to make sure a snap ring is included or > you > may have to buy it separately. > > There's also a DBA-600 that is a connector like you want with a > female > BNC so you don't have a cable attached to your tray. You put a BNC on > the cable and connect it to this adapter. About the same price as the > 9-30-10 but of course you have to do the BNC too. > > http://hangar-10.com/products/Bnc-Tray-Adapter-W%7B47%7DSna > > * > > > * > ------------------------------------------------------------------------------------- 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.