Airliner Avionics
Engine FADECs, going slightly off piste here: Frankly having to worry about fuel mixture, carburettor icing, priming pumps, magnetos etc. is absolutely prehistoric !! Like most of us; I can casually reach into my average 2008 car in any weather, any temperature, turn the key and it will start, (while I scrape the ice off the windscreen). But a C150 or equivalent??
That's why commercial airliner FADEC installations are all dual channel, fault tolerant, built with highly screened electronic components. They are also quite expensive - LRU cost for a FADEC is typically between a quarter million and a half million dollars. Yes, the actual cost to screw one together is a fraction of that but still approaches six figures. Further, while GA isn't as bad a commercial aircraft, the FADEC is subject to far greater and much more frequent environmental extremes than automotive installations (and large, frequent, and rapid temperature fluctuations are hell on electronics).
It actually doesn't. It's got better instruments to fly in nice weather and it's fairly trivial to land any light aircraft without any instruments when you've got a bit of experience, so no need for any serious redundancy. Also, if one instrument doesn't work, you always have a chance at postponing your flying for a day or two, whereas airlines would go bankrupt without a solid MEL dispatch availability. Horses for courses.
I think the question was not so much about the despatch reliability and ultimate redundancy of an avionics fit, it was about what it could do when it was working and the answer to that is GA instrumentation will always be ahead of airliner kit because GA manufacturers can use the latest tech...
A big problem with applying FADEC technology to your Cessna is cost. Compared to carburetors, electronics have rather unforgiving failure modes - carbs tend to wear gradually, slowly shifting - while electronics simply quit, often with little or no warning. When that happens in your car, you pull over to the side - when that happens in your GA aircraft, best case is you make forced landing.
That's why commercial airliner FADEC installations are all dual channel, fault tolerant, built with highly screened electronic components. They are also quite expensive - LRU cost for a FADEC is typically between a quarter million and a half million dollars. Yes, the actual cost to screw one together is a fraction of that but still approaches six figures. Further, while GA isn't as bad a commercial aircraft, the FADEC is subject to far greater and much more frequent environmental extremes than automotive installations (and large, frequent, and rapid temperature fluctuations are hell on electronics).
That's why commercial airliner FADEC installations are all dual channel, fault tolerant, built with highly screened electronic components. They are also quite expensive - LRU cost for a FADEC is typically between a quarter million and a half million dollars. Yes, the actual cost to screw one together is a fraction of that but still approaches six figures. Further, while GA isn't as bad a commercial aircraft, the FADEC is subject to far greater and much more frequent environmental extremes than automotive installations (and large, frequent, and rapid temperature fluctuations are hell on electronics).
But there are millions and millions of Engine Control Modules driving around in cars and trucks today. They start engines in the depths of Alaskan and Canadian Winters, and in the middle of Summer in the desert. Car ECMs look at atmospheric pressure, OAT, mass airflow etc etc, and it would be simple to extend the engine map for an aviation engine envelope. Car ECMs also allow and adjust for load, and optimise the ignition timing and fuel mixture hundreds of times a second. They control emissions equipment and modulate charging systems by varying the mark-space ratio of the drive signal. They can be quite sophisticated.
If a car ECM quits, yes, you just park up and call the tow truck, but in my long electronics experience, most problems come from bad connections - rarely the electronics themselves. In many years of driving, I have only once had a car quit on me through ECM electronics, and it restarted straight away and got me home, (albeit running at reduced performance). I took apart and sprayed all the plugs and sockets around the engine bay, and it was all back to normal, and hasn't missed a beat for 2 years since that happened.
Cars use a lot of plug and socket electrical connections because it makes the build process much quicker, but that also causes the majority of electrical problems down the line. (Gas turbine FADECS use gold plated connectors, which don't corrode and thus are more reliable). So, on your C150, you would not have plugs and sockets, but have screw/crimped/soldered terminals for every connection in the engine bay. You site the ECM in the cockpit, not outside with the engine, thereby protecting the electronics from extremes of temperature and vibration. And, yes, you make it dual channel, screened and fault tolerant. Cars already have a limp-home mode which keeps the engine running at reduced performance if important sensors malfunction. Or they use look-up values in the absence of sensor data. Not difficult, and doesn't have to be expensive.
.
Last edited by Uplinker; 16th May 2020 at 10:23.
Uplinker, the difference is auto manufactures make them by the millions. Aviation makes them by the thousands - so massive economies of scale come into play. And that automotive engine that started at +40 C doesn't see minus 40C an hour later - aircraft engines do (granted, not as dramatic on piston engines as on jets, but still dramatic temp changes). That rapid thermal cycling is hell on electronics - cracking solder joints and solid state components. You can't just take an ECU out of your Honda, change the software, and expect it to survive on an aircraft - the operational environments are totally different.
Finding electronics that can survive that is expensive, and maintaining them is even worse. If the ECU goes bad in your car, most likely they throw it away and install a new one. But if the ECU costs $50k, you want to be able to fix it. Encasing all the components in some matrix to protect them from vibration (something that is commonly done on automotive electronics) makes them nearly impossible to repair.
Oh, and not many automotive electronics are protected against HIRF and Lightning. Aircraft have to be.
Finding electronics that can survive that is expensive, and maintaining them is even worse. If the ECU goes bad in your car, most likely they throw it away and install a new one. But if the ECU costs $50k, you want to be able to fix it. Encasing all the components in some matrix to protect them from vibration (something that is commonly done on automotive electronics) makes them nearly impossible to repair.
Oh, and not many automotive electronics are protected against HIRF and Lightning. Aircraft have to be.
Agreed, but check the last paragraph of my previous post 
Here, you're talking about two different things, capability and reliability.
My RV-9 is, in some ways, more advanced than the latest A350. If something goes out of limits, it won't just go "PING!" and require you to look at the ECAM to find out what went wrong. It will tell you, in your headset "Oil Pressure" or "Electrical Current" or any number of other things. IT has synthetic vision with terrain shading, a glide ring showing what points on the ground I can reach, based on current environment variables, can have touch-screen's installed if I want, displays a geo-referenced position on the visual or approach chart and is interfaced with an electronic circuit breaker system (though, granted the A350 has the last two as well). Another EFIS manufacturer provides for a camera input on which you can superimpose your PFD symbology, allowing a FLIR camera to be fitted for low-light operations.
That being said, while no light single will have autoland capability, I think many folk would be surprised to see the amount of redundancy built in to your typical IFR Experimental. Dual ADAHRS, triple screen (often with a third standby EFIS), dual GNSS and oftentimes dual batteries or alternators as well.
My RV-9 is, in some ways, more advanced than the latest A350. If something goes out of limits, it won't just go "PING!" and require you to look at the ECAM to find out what went wrong. It will tell you, in your headset "Oil Pressure" or "Electrical Current" or any number of other things. IT has synthetic vision with terrain shading, a glide ring showing what points on the ground I can reach, based on current environment variables, can have touch-screen's installed if I want, displays a geo-referenced position on the visual or approach chart and is interfaced with an electronic circuit breaker system (though, granted the A350 has the last two as well). Another EFIS manufacturer provides for a camera input on which you can superimpose your PFD symbology, allowing a FLIR camera to be fitted for low-light operations.
That being said, while no light single will have autoland capability, I think many folk would be surprised to see the amount of redundancy built in to your typical IFR Experimental. Dual ADAHRS, triple screen (often with a third standby EFIS), dual GNSS and oftentimes dual batteries or alternators as well.
Actually there’s a few light singles now equipped and certified to do completely autonomous autolands
An ILS is not even required
Join Date: May 2003
Location: Canada
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
Already certified on several GA single such as the TBM, Cirrus, Piper,...
Not exactly autoland but Garmin Autonomi can take over in case of crew LOC (Helios 522) and land all by itself to the nearest suitable airport, even announcing intentions to ATC and reassuring passengers.
Already certified on several GA single such as the TBM, Cirrus, Piper,...
Garmin Autonomí: Autoland Activation
Already certified on several GA single such as the TBM, Cirrus, Piper,...
Garmin Autonomí: Autoland Activation
It lands the aircraft automatically therefore it is autoland
In fact, more so than traditional airline transport aircraft that require the crew to arm the system
