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Airliner Avionics

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Airliner Avionics

Old 15th May 2020, 13:09
  #21 (permalink)  
 
Join Date: Nov 1999
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Originally Posted by Airmann View Post
What I would like to see however is a transfer of turbulence data from aircraft to a ground station that could then be relayed to other aircraft. I believe that a lot of work is going into turbulence forecasting and its pointless. Much better to just take the data from g loading sensors on board and have the manufacturers work out a way to catagorize it according to turbulence levels and then have that data sent to a centralized location via ACARS.

As for synthetic vision, like others have mentioned it really doesn't add much if one can do a CAT2 or better autoland. As for terraint awareness we have a TAWS database on board, sure the display of terrain on an ND isn't as 'high tech' as synthetic vision but it does the job. The danger is flying the plane using the synthetic vision like a video game. You don't want that in a commercial setting. Having used a HUD for landing I can honestly say that I see no use for it except for certain airports...…....
An automatic turbulence reporting network is a very good idea - aircraft talking to other aircraft in the background, like TCAS, and only popping up with alerts when necessary. That would be good

I agree with Airman's other points too. As I said in post #6, there is no point having synthetic vision or whatever just because you can. You still need to have SA and fly an aeroplane, and turning the whole process into a video game could cause its own problems, with barely qualified pilots thinking they can fly. (I am not being a dinosaur about this, I write (simple) code myself, and am well into technology).

Light aircraft instrumentation has been awful though, so improvements here would be good. It was bloody difficult to track or fly a hold around an NDB in a light SEP/MEP, but only really because the NDB pointer and the compass bug were on different instruments - and sometimes, the "compass" card had to be manually aligned to a real compass every 10 mins, I mean for crying out loud, as if you haven't got enough to do just flying the thing !!. When you can overlay the NDB needle onto the track pointer of a proper compass or ND, NDB tracking is child's play - so easy ! (Yes, yes, I know, we don't track NDB's any more )

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??
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Old 15th May 2020, 13:38
  #22 (permalink)  
 
Join Date: Mar 2006
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Originally Posted by Airmann View Post
The main advancements in the GA catagory relate to

What I would like to see however is a transfer of turbulence data from aircraft to a ground station that could then be relayed to other aircraft. I believe that a lot of work is going into turbulence forecasting and its pointless. Much better to just take the data from g loading sensors on board and have the manufacturers work out a way to catagorize it according to turbulence levels and then have that data sent to a centralized location via ACARS.
Your idea on the sharing of turbulence data has already been brought to life.

https://business.weather.com/news/ws...ovide-tracking

It has its limitations though.

Last edited by Check Airman; 16th May 2020 at 03:09.
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Old 15th May 2020, 21:12
  #23 (permalink)  
 
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Originally Posted by Uplinker View Post
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??
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).
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Old 16th May 2020, 07:44
  #24 (permalink)  
 
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Originally Posted by FlyingStone View Post
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 get the point about redundancy but my sailplane has multiple redundant inertial/nav systems running off independent power supplies and a certified EFIS with backup. I fly IMC quite a bit and could go IFR if I wanted to.

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...
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Old 16th May 2020, 10:13
  #25 (permalink)  
 
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Originally Posted by tdracer View Post
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).
Yes, an actual FADEC - operating a gas turbine engine is a complicated beast, and is not cheap.

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.
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Old 16th May 2020, 20:41
  #26 (permalink)  
 
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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.
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Old 17th May 2020, 09:12
  #27 (permalink)  
 
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Agreed, but check the last paragraph of my previous post
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