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  #81  
Old 04-06-2019, 08:12 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
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Originally Posted by keitht View Post
Ross,

I understand the points you are making but don’t agree with you. There is a level of design, analysis and testing that is essential to ensure that these kinds of systems meet the expected performance, availability, redundancy and monitoring required of the application. I find it hard to believe that all these required tasks can be done at the required level of fidelity and cost that is consistent with the market place selling price for the amateur built experimental market. The alternative is the iterative “suck it and see approach” . I may be wrong but in the absence of a comparable certified unit that is most likely how the work gets done. Please enlighten me if you have a formal process in place that would stand up to examination by any of the certification authorities. I do agree with you that wiring quality, connectors, and general workmanship are significant contributing factors to electrical system failures in the EAB world (I too have seen some examples that were just plain dangerous).
Comparing the availability and reliability of a clone of a certified hydromechanical fuel injection controller for a single engine reciprocating powerplant with an equivelent EFI, the EFI would out of sight in terms of price. There just isn’t a comparison. Sure you can buy an EFI for a comparably price but your not getting a comparable product in terms of proven reliability. Like most other non certified equipment there are sales pitch claims for failure rates but no substantiation.

KT
I agree that a new-to-the-field company and ECU design probably won't be as reliable as it could be given the budgets allowed in Experimental aviation however we have the advantage that we are not new to the field.

Perhaps you are not aware that we started out in the automotive field in 1994 and have sold about 10,000 controllers collectively with many millions of hours on them in more demanding environmental conditions than what aviation products endure (salt, vibration, heat, low maintenance frequency etc.) We've sold hundreds of ECUs for military use as well (they could buy any unit they wanted). Where do you draw the line with what is reliable enough? Do you want to see 10,000, a million, 10 million hours of demonstrated reliability?

Our goal is to make the entire system more reliable than the piston engine they are attached to.

Reliability has been evolutionary. We've learned a lot as we went down this path and improved many things along the way based on field experience. We're on the 5th generation ECU now. Yes, the first gen systems were relatively crude and less reliable than what we've produced in the last 20 years but we still have customers running those early units today- thousands of hours on each of those old units by now.

We consider the 25 years and millions of hours operating in the real world as the REAL proof of reliability and durability. Theoretical stats and studies mean nothing in reality, only demonstrated reliability and durability in the actual operating environment.

Some of the most robust mechanical and electronic designs are based on evolutionary improvements learned from field experience. Few designs, of anything, are 100% perfect at the first iteration. I've seen small teams of good people turn out excellent products- and some bad ones too just like huge companies with large engineering departments.

FMEA and vetting processes may well identify issues during the design and testing stage but we see many examples of in depth design analysis doing nothing to deliver a reliable and durable product in the end- rocket and gas turbine engine failures, FBW systems, MCAS etc. The list is huge. The real world is ruthless. Your product is either reliable or it isn't and you can't hide these days in the latter case.

Dynon has turned out some wonderful equipment for our world which isn't certified. It's been very well received I think. Conversely, I can think of some certified components I've dealt with which are quite terrible. Certification is no guarantee of superior reliability or durability in my experience. Might or might not be quite good.

In other posts a few years back, I've listed the failures we've seen over the years, should you choose to believe my information.

I'd ask what you base your statement on that a mechanical FI servo is more reliable than our EFI? Is this based on a feeling or facts about both systems?
And I'll ask you if you have any experience either installing or operating EFI in aircraft? General experience in another field really doesn't apply here IMO.

One of our bench test ECUs ran for 145,000 hours before being replaced with a newer model. No maintenance on that unit. Do you know of a servo or carb going that long without being touched? There are no moving parts in an ECU to wear out or go brittle and crack. We offer redundant systems for even higher confidence and that is the most popular choice for RV guys for the last few years.

The electronic and fuel hardware such as injectors have proven to be very reliable if installed as directed. I documented the sensor failures and some other failures we've seen in over the years in that earlier post.

EFI revolutionized reliability and lowered maintenance by an order of magnitude in the automotive world over carbs and points. No reason to expect anything different in aviation- if done correctly using similar components.

Choice of fuel systems is up to the user. I've always said if you prefer mags, servos and carbs, you can install those. Nobody is forcing anyone to use EFI/EI or change their perceptions about it. I find most of our aviation customers are pretty savvy types and are comfortable and informed about their choices.

We don't hard sell. We simply say this is what we've done, this is what the product does, this is our track record and I've turned lots of people away from our products back towards conventional engine controls when I don't think our products fit their skills, budgets or missions. EFI/EI isn't for everyone.

Back on track about electrical redundancy here. No matter how reliable our electronics might be, they don't function without power. We consider backup power essential and we have a simple recommendation on how to supply that. I've been using that system in our company 6A since my forced landing over a decade ago due to alternator failure and lack of proper voltage warning devices. Another lesson learned from the school of hard knocks...
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 445.2 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ



Last edited by rv6ejguy : 04-06-2019 at 08:29 AM.
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  #82  
Old 04-06-2019, 08:13 AM
rocketman1988 rocketman1988 is offline
 
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"...Yet we second guess Lycoming all the time..."

I spoke with an engine manufacturer (continental) some years ago about electronic ignition and why it wasn't being used. He indicated that it was more about litigation than anything else...the systems are out there and they work, however, the liability of making a substantial design change like EI just wasn't palatable for the company. That is a causal factor as to why the engine designs haven't changed substantially in 50+ years...liability, not the lack of technology.
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  #83  
Old 04-06-2019, 08:32 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by rv6ejguy View Post
The wiring for the systems and backup power has been available for several years on our website (Aircraft Page, under Documentation) and supplied with each system ordered.
Right...http://www.sdsefi.com/dualecu4.pdf

Those are harness diagrams for the EFI/EI. The total guidance regarding power supply is can be summed as "hook up two battery feeds":



The primary feed isn't from the master switch in anyone's airplane, not in the vernacular of the aircraft world, as the master switch grounds a contactor. So is there a conventional master switch, a master contactor, an ANL feeding a main bus, and then a diode to an essential bus, plus an essential bus switch, per Nuckolls?

If the drawing attempts to describe a dedicated EFI/EI feed, where is the circuit protection, and the wire size?

How is the aux battery charged? How do you know it is being charged? Can loaded voltage be checked on the runup pad, and in flight?

Quote:
...isolation from the alternator and main battery is provided by the master contactor.
What master contactor? I don't see a master contactor.

Look, I'm not spelling this out to tweak your nose. The diagrams you supply are, in a very practical sense, limited to the equipment you supply, and are quite vague beyond those limits. I understand why a vendor might want to take that position. However, it quite naturally leads to folks creating the rest of the system all by themselves, with mixed results.

Leaders lead. Make it so a new builder who wants EFI can simply wire the complete power supply by following detailed drawings. You need not create an entire whizbang aircraft electrical system of your own. Integrate SDS power requirements into a standard Nuckolls diagram, or an equivalent with a Nuckolls level of detail, or just endorse Z-19. Do whatever it takes to get some standardization into the systems supporting your product, because in the end, you're the electrically dependent choice.
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  #84  
Old 04-06-2019, 11:32 AM
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JoopSJ JoopSJ is offline
 
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Quote:
Originally Posted by DanH View Post
...
Leaders lead. Make it so a new builder who wants EFI can simply wire the complete power supply by following detailed drawings. You need not create an entire whizbang aircraft electrical system of your own. Integrate SDS power requirements into a standard Nuckolls diagram, or an equivalent with a Nuckolls level of detail, or just endorse Z-19. Do whatever it takes to get some standardization into the systems supporting your product, because in the end, you're the electrically dependent choice.
YES!

The more I read about this topic the more confused and insecure I become. I am one of those folks that have a hard time with electrons. I know all the theory but I don't seem to be able to visualize how they put things to work.

I am thrilled about the new technology and want that in my aircraft.
But every time I see a fairly new car on the roadside (computer problems), while driving my 1992 400K-km Volvo (never failed), I am well aware of the need of a solid electrical system to feed my electrical dependent engine.

I need a good schematic so I can buy the parts and hook things up. Exactly as DanH is indicating. And with good instructions how to test the system before *each* flight. I am willing to spend all the money that is needed. And I don't really need to know why the system is as it is.

In a way we can say that Dan's call for the "leader to lead" is complied with by the EFII's Bus Manager. I am inclined towards that solution. But then I remember a tread on this forum where the product is criticized for not covering a certain failure scenario. A scenario of which others say is unrealistic. And that's where this forum does not help folks like me.

Is it possible that the absence of clear criteria's of what the system should achieve, and therefore having many people trying to re-invent the wheel, inhibits the consensus on the systems design?
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  #85  
Old 04-06-2019, 12:12 PM
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rmartingt rmartingt is offline
 
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Originally Posted by KatanaPilot View Post
The airplanes we fly don?t meet Part 23 or even ASTM ?certification? (RV-12 excepted). They aren?t clones of any certified airframe. Yet we accept the thousands of them flying (with build quality all over the map) and hundreds of thousands of hours of flight time as proof that they are reasonably safe and reliable, don?t we?
More to the point, if you just can't stand to use anything but type-certified designs, go buy and fly a type-certified airplane. Many of us are attracted to the homebuilt world specifically because we aren't tied to decades-old certified equipment, and see real advantages (not just "new shiny for the sake of new shiny" ) to things like EFI.


As one other user's sig points out... "build the airplane you want to build, not the airplane others want you to build".

Quote:
Originally Posted by rocketman1988 View Post
"...Yet we second guess Lycoming all the time..."

I spoke with an engine manufacturer (continental) some years ago about electronic ignition and why it wasn't being used. He indicated that it was more about litigation than anything else...the systems are out there and they work, however, the liability of making a substantial design change like EI just wasn't palatable for the company. That is a causal factor as to why the engine designs haven't changed substantially in 50+ years...liability, not the lack of technology.
Don't forget the certification costs too. Certifying something is expensive, and new/modified item usually has to meet more stringent requirements than the things it's replacing. Plus, between turboprops getting ever smaller and displacing large piston engines, and later the collapse of the general aviation market, the impetus and funding to make more than minor incremental improvements to aircraft piston engines all but disappeared. If you were in the shoes of Cessna/Lycoming/Piper/etc., and you were looking at "spend a whole bunch of R&D money to certify this new system and try to make the costs back on relatively few sales to a notoriously tightwadded market" vs. "pick something off the shelf and use it, at minimal or no R&D cost"... which would you pick?
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  #86  
Old 04-06-2019, 12:31 PM
rocketman1988 rocketman1988 is offline
 
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Default ...and

"...But then I remember a tread on this forum where the product is criticized for not covering a certain failure scenario. A scenario of which others say is unrealistic. And that's where this forum does not help folks like me..."

As DanH has alluded to, it would be wonderful to have a wiring diagram to use...one that folks could just duplicate and know that it works.

That being said, the will NEVER be a perfect solution. Any solution will have some risk of failure. It comes down to how risk averse the individual using the system is. There are many Bus Manager systems flying with no issues; is it perfect? No, but the folks using them accept the minimal risk. Others do not want that risk and they do not use them, yet they try and "roll their own system" that is "better". A proven (not perfect) diagram would really be helpful.

As has been posted numerous times, there are some really well thought out diagrams in the Aeroelectric Connection. There are also some folks that would argue that there are better options...again, there are multiple solutions, and it still comes down to the builder's aversion to risk.

I also understand possible reasons why vendors of the EFII products are hesitant to post more than a basic overview of a recommended wiring diagram.

Maybe there are some experts here that want to tackle the problem and provide the solution...

No takers? Didn't think there would be. Probably not a good idea in this litigious society...
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  #87  
Old 04-06-2019, 12:47 PM
keitht keitht is offline
 
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Default EFI?s and failure rates

Ross,
Thanks for the reply - but you didnt provide any actual data.

The difference between an automotive EFI and an aircraft EFI is like comparing fly by wire flight controls with an autopilot. Autopilot systems like automotive EFI are typically single string with a level of monitoring to detect errors and failures for disconnection and diagnosis. FBW on the other hand has significant monitoring dual disimilar computing paths with voting planes typically at input sensors, mid value and output values. There are redundant paths avaiable to meet availability requirements. There are a number of well proven competing architectures - just like the primer wars those in the business have their preference. Just as a data point - for a Cat 111B autoland (zero zero)in a large commercial transport all three channels of autopilot must be engaged - the period of exposure is small - less than 10 minutes but the availability cannot be met on two channels. For a typical FBW system there are multiple lays of full up capability on top of a bare bones analog primary ?last ditch? system.
If you had mentioned the general architecture you favor, that you design all your electronic hardware to meet the requirements of DO 254 and your software meets DO178 and your requirements and validation procedures are written in VHDL or DOORS, you have single entry, single exit software routines, explained your manufacturing processes as meeting ISO 9000 then I would say you are going in the right direction and would be more inclined to consider your products. I saw no data in your reply, nothing that I could hang my objective hat on and dig further. Frankly your reply didnt even pass the first gate in any objective assessment. I did see some condescending comments that have no place in any discussion on EFI or on this forum.
The big market for EFI is the certified segment, EAB is small beer. Having been in business for a long time I wonder why, if you are on the right track you dont have a certified product in the stable?
KT
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  #88  
Old 04-06-2019, 02:40 PM
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Bill Boyd Bill Boyd is offline
 
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Quote:
Originally Posted by DanH View Post
Right...http://www.sdsefi.com/dualecu4.pdf

Those are harness diagrams for the EFI/EI. The total guidance regarding power supply is can be summed as "hook up two battery feeds":



The primary feed isn't from the master switch in anyone's airplane, not in the vernacular of the aircraft world, as the master switch grounds a contactor. So is there a conventional master switch, a master contactor, an ANL feeding a main bus, and then a diode to an essential bus, plus an essential bus switch, per Nuckolls?

If the drawing attempts to describe a dedicated EFI/EI feed, where is the circuit protection, and the wire size?

How is the aux battery charged? How do you know it is being charged? Can loaded voltage be checked on the runup pad, and in flight?



What master contactor? I don't see a master contactor.

Look, I'm not spelling this out to tweak your nose. The diagrams you supply are, in a very practical sense, limited to the equipment you supply, and are quite vague beyond those limits. I understand why a vendor might want to take that position. However, it quite naturally leads to folks creating the rest of the system all by themselves, with mixed results.

Leaders lead. Make it so a new builder who wants EFI can simply wire the complete power supply by following detailed drawings. You need not create an entire whizbang aircraft electrical system of your own. Integrate SDS power requirements into a standard Nuckolls diagram, or an equivalent with a Nuckolls level of detail, or just endorse Z-19. Do whatever it takes to get some standardization into the systems supporting your product, because in the end, you're the electrically dependent choice.
Dan, thanks for assuring me I'm not losing my mind - I read Ross's reply last night and searched his site for the promised electrical power distribution diagrams and came back again this morning over coffee to look some more...

I'd love to see what Ross and his cadre of adopters consider a reliable power scheme, and I trust he'll post one up soon. In the mean time I think your inference that AeroElectric Connection diagrams remain more-or-less state-of-the-art is correct, or at least gospel enough for me as I try to finalize my electrical system planning.
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  #89  
Old 04-06-2019, 05:40 PM
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johnbright johnbright is offline
 
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Default Bus Manager

Quote:
Originally Posted by JoopSJ View Post
YES!

... In a way we can say that Dan's call for the "leader to lead" is complied with by the EFII's Bus Manager. I am inclined towards that solution. But then I remember a tread on this forum where the product is criticized for not covering a certain failure scenario. A scenario of which others say is unrealistic. And that's where this forum does not help folks like me.

...
I lost confidence in Bus Manager when I saw single points of failure in the dual pump control.

https://drive.google.com/file/d/1Jbi...ew?usp=sharing

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Last edited by johnbright : 04-20-2019 at 05:05 PM.
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  #90  
Old 04-06-2019, 05:49 PM
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Walt Walt is offline
 
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Originally Posted by keitht View Post
The big market for EFI is the certified segment, EAB is small beer. Having been in business for a long time I wonder why, if you are on the right track you dont have a certified product in the stable?
KT
If I recall the Teledyne/Aerosance FADEC was the greatest thing since sliced bread for a while... they ended up having so many issues they eventually discontinued it (big company with big $$). A good friend of mine was forced to pull the entire setup (which never worked properly) and convert to "standard" FI/Ign. Like many folks he wanted the new "state of the art" system on the new plane he was building (it almost killed him before he removed it).
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Last edited by Walt : 04-06-2019 at 05:55 PM.
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