---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 05/09/22: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:48 AM - The value of FMEA (Robert L. Nuckolls, III) 2. 04:54 AM - Re: Re: Too many Circuit breakers.... (Robert L. Nuckolls, III) 3. 06:37 AM - Re: Re: Too many Circuit breakers.... (Charlie England) 4. 09:00 AM - Re: Re: Too many Circuit breakers.... (Robert L. Nuckolls, III) 5. 10:49 AM - Re: The value of FMEA (user9253) 6. 11:08 AM - Re: Re: Too many Circuit breakers.... (Robert L. Nuckolls, III) 7. 11:11 AM - Re: Re: Too many Circuit breakers.... (Robert L. Nuckolls, III) 8. 11:20 AM - Re: Re: The value of FMEA (Robert L. Nuckolls, III) 9. 12:45 PM - Re: Re: Too many Circuit breakers.... (Charlie England) 10. 02:00 PM - Re: Re: Too many Circuit breakers.... (Sebastien S) 11. 04:56 PM - Re: Re: Too many Circuit breakers.... (Charlie England) ________________________________ Message 1 _____________________________________ Time: 03:48:21 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: The value of FMEA I'll encourage everyone to view this video on youtube. It's an excellent demonstration of competent flight testing but a sobering example of hazards to accomplish a competent FMEA. Electrical system details are offered at about 44 minutes into the video. https://youtu.be/4PHTVTw_Y2A Failure of the engine in this story reminds me of the LancAir IVP accident where ignition system was designed to fail. We don't have enough wiring detail to do an after action debrief on this incident but I hope it's strong incentive to get our homework done before we take the active. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 2 _____________________________________ Time: 04:54:54 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... At 02:54 PM 5/7/2022, you wrote: > >Alright - looks like I might have some breakers to sell. >What's an ideal fuse block model for the ATC fuses. Any good brand >or model suggested? I'm scared of some of the stuff I see. > > >nuckolls.bob(at)aeroelect wrote: > > > > > > > > > The only thing on that list that I'd put on a breaker is the > alternator field supply. > > > > But even this is not necessary if you have something > > other than crowbar ov management. > > > >Do I read this as: Since I've got the LR3D I don't need a breaker >for the alternator even though BandC calls for one? Just put a fuse >where they call for breakers? NO! The B&C products FEATURE crowbar ov management . . . a system that expects to open the alternator field feeder during an ov condition. That protection CAN be a fuse but then you have no convenient way to reset in case of a rare but not zero probability of a nuisance trip. This is why you see a breaker in the field supply feeder in all of the z-figures when a B&C alternator controller -OR- crowbar ov module is incorporated. This is recommended whether or not you choose to use fuse blocks. >My ignitions - 2 Lightspeeds - What's the best protection for the >wires running from the panel to the back seat? I still need switches >to turn them on or off, might I be better off with a W31 Breaker >switch and that be it, or is the complexity of the W31 a risk? Part >of me would like to be able to reset it if the engine goes quiet and >I'm out of other options. Though 2 dying at once seems highly improbable. You have pretty much answered your own question. Review architecture and series of events that ended up trashing a nice LanceAir IVP a few years ago. http://aeroelectric.com/Reference_Docs/Accidents/N811HB_Feb2008_LA-IVp/ My post of last night suggests reviewing an accident that was probably a result of poor electrical system architecture. Being able to reset blown protection in flight is WAayyy down on the list of priorities for pilots. Electro-whizzies go belly-up for many MORE reasons than a fault that opens a breaker. When a breaker does open, it indicates (1) a DESIGN problem (see youtube narrative on P51 replica crash) or (2) something is broke (and resetting the breaker is not going to fix it). Judicious exercise of failure mode effects analysis leads to failure tolerant selection of appliances and architecture powering those appliances thus mitigating design issues. This leaves only a gross overload events for which a re-setable feeder protection is of no value. Besides, if something stops working in flight, one is well advised to get on the ground before trading your pilot's hat for a mechanic's hat. >Radio Master (Currently a W31 breaker switch) - people seem to be >moving away from avionics masters - is that really the best case these days? I was at Cessna circa 1965 when the avionics master was conceived . . . for the wrong reasons. Nonetheless, the concept flourished in virtually all GA aircraft in spite of no demonstrable risks to avionics and in spite of environmental qualification testing requiring that avionics be immune to normal and expected electrical stresses in the ship's power generation system. >Let the Garmin and Avidyne stuff suffer the brown-out during start >and reboot? Or go around twisting knobs off and on? I'd like to be >able to get rid of as much load during start. Normally, only things >I have is LED Nav lights and the engine monitor. (Engine monitor >only needs ~4 volts to run) Load shedding for the purposes of relieving stress on battery during start is a thing of yesteryear. A panel full of radios in a 1965 C172 was a significant load on a soggy battery suffering the abuse of starter motor adapted from farm tractors. Today's avionics draw a small fraction of that energy. Batteries are more robust. Starters get the fan fired up much faster. Load shedding for start assist is an idea that has pretty much evaporated. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 3 _____________________________________ Time: 06:37:18 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... snipped > Let the Garmin and Avidyne stuff suffer the brown-out during start and > reboot? Or go around twisting knobs off and on? I'd like to be able to get > rid of as much load during start. Normally, only things I have is LED Nav > lights and the engine monitor. (Engine monitor only needs ~4 volts to run) > > > Load shedding for the purposes of relieving > stress on battery during start is a thing of > yesteryear. A panel full of radios in a 1965 > C172 was a significant load on a soggy > battery suffering the abuse of starter motor > adapted from farm tractors. > > Today's avionics draw a small fraction of that > energy. Batteries are more robust. Starters > get the fan fired up much faster. Load shedding > for start assist is an idea that has pretty > much evaporated. > > Bob . . . > These days, with EFIS equipment, it's more about inconvenience than load shedding. Some EFIS products take 2-3 minutes to boot and self-calibrate, and I've seen them 'lock up' during engine start. If they reboot due to brownout at engine start, that 3 minutes feels like half the planned flight time. ;-) If they lock up, then you typically have to power down the whole panel to get them to restart. ________________________________ Message 4 _____________________________________ Time: 09:00:02 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... >Because the Avidyne IFD has dual power inputs that are diode or'd, >I'll feed one side from the Avionics and the other from the >Essential bus. Other items don't so I'll put two schottky diodes in >to prevent backfeeding. Are you exploiting any of the z-figures? Two diodes should never be needed. It would be exceedingly useful if you would sketch your distribution plan and share it on the List. It's that ol' "Picture worth 10,000 words thingy". > Or, what 20A schottky diode is recommended that can support my > whole essential bus? Can't see where I can buy the AEC9001-1. Essential or endurance bus? And do you KNOW what the total load on that bus is? The 9001 was discontinued because it was a bad idea. Over the years we got wrapped tightly around the 'save energy' axle . . . and Schottky diodes planted the seed of some poor decisions. For the past 25 years or so, I've showcased the bridge rectifier assembly as a ready-off-the- shelf solution to diode isolation in our distribution systems. Inexpensive, dozens of sources, easy wiring (fast-ons), easy mounting (one screw in the middle), zero risk for shorting (no insulators required). Down side? A few tenths of a volt greater voltage drop. Okay, what are the OBSERVABLE benefits for eliminating that extra drop? ZERO So what is the return on investment for fiddling with that gold-plated solution to lowering voltage drop? I suggest its on a par with going lithium just to save weight. There are no benefits to either (1) saving of a few tenths of a volt -or- (2) a few pounds in an airplane. Both are more expensive and fussier to implement/maintain with performance improvements difficult to measure and impossible to demonstrate. >One ignition will have a 3 position switch - middle position will go >to a small standby >battery for power in case the world is coming undone. Do you not plan to maintain the ship's battery in an airworthy condition? I.e. periodic cap-checks to maintain design goals? If not, then what is your game plan for maintaining a SECOND battery in an airworthy condition? Over the years, we've studied the occasional dark-n-stormy- night narrative from one of aviation journals. A common characteristic of those stories is that they seldom, if ever, describe shortcomings in either selection of hardware or preventative maintenance that would have kept that event from occurring. They ALWAYS conjure up a litany of advice and cautions for how to deal with that situation should it happen AGAIN to you! Failure tolerant design and maintenance strives to prevent any failure from becoming a dark-n-stormy night story over beers . . . or an obituary. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 5 _____________________________________ Time: 10:49:12 AM PST US Subject: AeroElectric-List: Re: The value of FMEA From: "user9253" If the accident aircraft had been wired per Z-101, the engine would not have quit and electrical power to the main power bus would not have been lost. Of course the plane still would have crashed because the landing gear failed. If the 30 amp circuit breaker had not been installed to protect the main power bus, then the main power bus would not have lost electrical power. A fuselink would have been a better choice than a circuit breaker. Most small planes do not have any short circuit protection for the main bus other than the battery contactor. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=506706#506706 ________________________________ Message 6 _____________________________________ Time: 11:08:46 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... > > >These days, with EFIS equipment, it's more about >inconvenience than load shedding. Some EFIS >products take 2-3 minutes to boot and >self-calibrate,=C2 and I've seen them 'lock up' >during engine start. If they reboot due to >brownout at engine start, that 3 minutes feels >like half the planned flight time. ;-)=C2 If they >lock up, then you typically have to power down >the whole panel to get them to restart.=C2 Brown-out mitigation is indicated for sure Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 7 _____________________________________ Time: 11:11:03 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... >These days, with EFIS equipment, it's more about >inconvenience than load shedding. Some EFIS >products take 2-3 minutes to boot and >self-calibrate,=C2 and I've seen them 'lock up' >during engine start. If they reboot due to >brownout at engine start, that 3 minutes feels >like half the planned flight time. ;-)=C2 If they >lock up, then you typically have to power down >the whole panel to get them to restart.=C2 If I were qualifying an electro-whizzy for TC aircraft, DO160 power input tests have to demonstrate timely fault free recovery under various power input conditions. I would not be able to put such devices on a TC aircraft. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 8 _____________________________________ Time: 11:20:58 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: The value of FMEA At 12:46 PM 5/9/2022, you wrote: > >If the accident aircraft had been wired per Z-101, the engine would >not have quit and electrical power to the main >power bus would not have been lost. Of course the plane still would >have crashed because the landing gear failed. >If the 30 amp circuit breaker had not been installed to protect the >main power bus, then the main power >bus would not have lost electrical power. A fuselink would have >been a better choice than a circuit breaker. >Most small planes do not have any short circuit protection for the >main bus other than the battery contactor. Precisely. Any circuit protection upstream of dedicated feeder protection should have been ROBUST . . . like a current limiter. It would be interesting to see the gear control/annunciation logic. I think I would have preferred to shut the pump off based on pressure . . . not limit switches. I would power the hydraulic system thru a current limiter at the battery contactor. Engine critical devices need their own, dedicated bus structure with SHORT access to the well maintained battery. Do I recall that he experienced engine stoppage earlier in the flight as well? Having a properly responding engine might have mitigated the outcome if he had more options for energy management during approach/touchdown . . . but yeah that gear collapse was a game changer. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 9 _____________________________________ Time: 12:45:49 PM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... On Mon, May 9, 2022 at 2:29 PM Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > These days, with EFIS equipment, it's more about inconvenience than load > shedding. Some EFIS products take 2-3 minutes to boot and self-calibrate, =C3=82 > and I've seen them 'lock up' during engine start. If they reboot due to > brownout at engine start, that 3 minutes feels like half the planned flig ht > time. ;-)=C3=82 If they lock up, then you typically have to power down t he > whole panel to get them to restart.=C3=82 > > > If I were qualifying an electro-whizzy for TC > aircraft, DO160 power input tests have to demonstrate > timely fault free recovery under various > power input conditions. I would not be able to > put such devices on a TC aircraft. > > > I'll bet you couldn't sell a $100,000 certified EFIS array for $5,000 (or under $2K on the used market, either. ;-) I doubt that any of the newer exp models have the same 'lockup' issues, but it can happen with some of the near-prehistoric ones (pre-turn of the century). But once up and running, they're about as solid as the $100,000 certified models. Many homebuilt a/c could never pass FAA certification either, but they perform their missions better than any certified a/c. We play the cards we're dealt (or can afford to purchase). Charlie ________________________________ Message 10 ____________________________________ Time: 02:00:12 PM PST US From: Sebastien S Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... One of the rockets I fly has a current production GRT which has to be left o ff for engine start or it goes dark and locks up. Once the engine starts we q uickly turn it on and check that the red idiot light is out. If it=99s not then we don=99t know what the problem is but since oil pressure i s a possibility I would just shut it down. Not ideal. > On May 9, 2022, at 13:46, Charlie England wrote: > > =EF=BB > > >> On Mon, May 9, 2022 at 2:29 PM Robert L. Nuckolls, III wrote: >>> These days, with EFIS equipment, it's more about inconvenience than load shedding. Some EFIS products take 2-3 minutes to boot and self-calibrate,=C3 =82 and I've seen them 'lock up' during engine start. If they reboot due to b rownout at engine start, that 3 minutes feels like half the planned flight t ime. ;-)=C3=82 If they lock up, then you typically have to power down the w hole panel to get them to restart.=C3=82 >> >> If I were qualifying an electro-whizzy for TC >> aircraft, DO160 power input tests have to demonstrate >> timely fault free recovery under various >> power input conditions. I would not be able to >> put such devices on a TC aircraft. >> >> > I'll bet you couldn't sell a $100,000 certified EFIS array for $5,000 (or u nder $2K on the used market, either. ;-) > > I doubt that any of the newer exp models have the same 'lockup' issues, bu t it can happen with some of the near-prehistoric ones (pre-turn of the cent ury). But once up and running, they're about as solid as the $100,000 certif ied models. > > Many homebuilt a/c could never pass FAA certification either, but they per form their missions better than any certified a/c. We play the cards we're d ealt (or can afford to purchase). > > Charlie > ________________________________ Message 11 ____________________________________ Time: 04:56:22 PM PST US Subject: Re: AeroElectric-List: Re: Too many Circuit breakers.... From: Charlie England snipped > Charlie, What's your brown-out booster look like? > > Getting real close! Thanks! > > Andy Sorry for the delay in answering this. There are lots of options out there. I picked one that had both a low enough input voltage, and plenty of 'headroom' on the higher voltage end, simply for better survivability. This is the one I used (with a few spares for future projects): https://smile.amazon.com/gp/product/B07XG323G8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 I set it up on the bench with an adjustable bench supply to maintain around 11V with an 8V supply voltage (the little blue block with a slot head screw is the adjustment). The old GRT EFIS had multiple diode-isolated power inputs, so I simply tapped the EFIS' primary power wire & ground to power the boost converter, and fed the converter's output to one of the spare power inputs on the EFIS. They're pretty small (~1" x 2.5") so I just drilled some ventilation holes in a plastic prescription bottle & used it for a case. the whole affair was basically just a bulge in the harness going to the EFIS. On the particular units I received, the output ground is common to the input ground, so I only needed one output connection to the EFIS. Note that some boost converters may actually isolate the grounds, so you need to check for that, and also check to be sure that tying them together (via the ground in the plane and the EFIS) won't be an issue for the converter. Also note that this particular unit is limited to 3 amps. It will probably handle most single EFIS units, but I wouldn't think powering more than one with it would be a good idea. On the other hand, you do get extras for other stuff. ;-) -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------------- 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.