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...