Airliners.net

Recently, I heard someone mention FADEC, Fully Automated Digital Engine Control. How does this work, and how common is it on most aircraft?

FADEC is like the engine control module you would have on your car. In old jet engines they used have mechanical fuel control units, these got replaced by FADEC which is a electronic device that controls the fuel and other engine components/accessories. It reduced parts, improves economics, improves reliability.

The engine has a lot of sensors that feed into the FADEC, this computer than knows how much fuel to add and at what rate of change to achieve the performance required by the pilots. It is also smart enough in most cases to prevent damage to the engine.

I would think almost every western airliner built these days would have FADEC engines, so it is very common.

neomax wrote:

Recently, I heard someone mention FADEC, Fully Automated Digital Engine Control. How does this work, and how common is it on most aircraft?

Think of FADEC like the computer in your car.

The computer controls the fuel flow as well as the variable guide vanes, bleeds etc. etc. In older engines most of the components FADEC controls were manually set or in the case of things like vanes weren't really moveable. All of this is done to give the motor its peak efficiency in that moment. I say moment because the system is constantly checking and tweaking to keep the efficiency consistent.

This is a very simple explanation to a fairly complex system. If you want to learn more I would google and read about it.


As for engines that are/aren't FADEC, on the airline side the only motor flying in large numbers that is not a FADEC motor I can think of is the JT8D.

You will discover the full advantages of FADEC if you look at accidents and crashes of jets who didn't have FADEC-equipped engines. Back in the days, before such computer-controlled engines were possible, you had at least one flight engineer. And often, each engine had it's engine power to be set separately, because the engines were not running at the same fuel consumption at the same thrust lever position. And even more importantly, the engines were over-sensitive to any wrong handling of the thrust lever or the even the airplane flying characteristics. You could stall the airflow into the engine and even surge the complete engine by just flying the aircraft "wrong". Also just pushing the thrust levers from idle to full power was not possible, you had the engines to run up and advance the levers slowly, sometimes pausing at a certain point and wait for some of the numbers in your gauges to settle at a certain speed. It was a lot of work...

You can read this crash report about a Iran Air 727-200, which crashed after an aborted approach, which resulted in the pilots in the flight engineer mishandling the old, non FADEC equipped engines:
http://avherald.com/h?article=435f1587&opt=7680


I guess some of the pilots on this board can explain that better than me. But todays engines seem rather insensitive and work in a fire and forget logic...

To make things very easy to understand to non-geniuses like me I think of FADEC as the equivalent of the electronic injection in the engines of modern cars, versus the old, temperamental carburetor-fitted cars....

CARST wrote:

You will discover the full advantages of FADEC if you look at accidents and crashes of jets who didn't have FADEC-equipped engines. Back in the days, before such computer-controlled engines were possible, you had at least one flight engineer. And often, each engine had it's engine power to be set separately, because the engines were not running at the same fuel consumption at the same thrust lever position. And even more importantly, the engines were over-sensitive to any wrong handling of the thrust lever or the even the airplane flying characteristics. You could stall the airflow into the engine and even surge the complete engine by just flying the aircraft "wrong". Also just pushing the thrust levers from idle to full power was not possible, you had the engines to run up and advance the levers slowly, sometimes pausing at a certain point and wait for some of the numbers in your gauges to settle at a certain speed. It was a lot of work...

You can read this crash report about a Iran Air 727-200, which crashed after an aborted approach, which resulted in the pilots in the flight engineer mishandling the old, non FADEC equipped engines:
http://avherald.com/h?article=435f1587&opt=7680


I guess some of the pilots on this board can explain that better than me. But todays engines seem rather insensitive and work in a fire and forget logic...

errr. not really.

Plenty of non-FADEC motors are two pilot aircraft. Example, the 737-100/200, DC9 family even some 767s have or had motors that weren't FADEC.
For example, Delta still has a hand full of CF6-80C2B6 powered 767-300ERs they got from Gulf Air. The rest of the fleet is either PW4062s or CF6-80C2B6F or CF6-80C2B8Fs (yes the F at the end does literally stand for FADEC)
FADEC is about engine performance.
and FWIW even now you can push the throttles all you want up it still takes the motor time to spool up. IIRC that is somewhat part of the EK 773 crash.

oldannyboy wrote:

To make things very easy to understand to non-geniuses like me I think of FADEC as the equivalent of the electronic injection in the engines of modern cars, versus the old, temperamental carburetor-fitted cars....

exactly. On old fuel controls the fuel flow was either set in the shop or on the run up pad. You can do the same thing with a carb on a car (or airplane )
FADEC does it all automatically.
like everything else in the world, the basic part of this is we have gone from a fully mechanical system to a system controlled by electronics.

neomax wrote:

Recently, I heard someone mention FADEC, Fully Automated Digital Engine Control. How does this work, and how common is it on most aircraft?

Slight correction, it's "Full Authority Digital Engine Control"

Martijn

deltal1011man wrote:

errr. not really.

Plenty of non-FADEC motors are two pilot aircraft. Example, the 737-100/200, DC9 family even some 767s have or had motors that weren't FADEC.
For example, Delta still has a hand full of CF6-80C2B6 powered 767-300ERs they got from Gulf Air. The rest of the fleet is either PW4062s or CF6-80C2B6F or CF6-80C2B8Fs (yes the F at the end does literally stand for FADEC)

I know that there are FADEC 2-man-cockpits, but I was speaking in a broader sense. And the majority of non-FADEC planes were still 3-man-cockpits, while most non-FADEC planes are from the 2-man-cockpit age. Also Boeing back then had to put a lot of work into the jurassic 737s to certify them as 2-pilot-planes. And AFAIK the early 767s at least had EEC.

deltal1011man wrote:

FADEC is about engine performance.

It is. But it does much more. And it would be absolutely WRONG to say FADEC only was developed for performance reasons.

deltal1011man wrote:

and FWIW even now you can push the throttles all you want up it still takes the motor time to spool up. IIRC that is somewhat part of the EK 773 crash.

I never said that this would be the case. I said you can firewall the throttles with FADEC, because FADEC will increase engine power slowly, no matter what you do to the throttles. That the engine isn't spooling up from idle to 100% is normal and I never wrote that.

deltal1011man wrote:

oldannyboy wrote:

To make things very easy to understand to non-geniuses like me I think of FADEC as the equivalent of the electronic injection in the engines of modern cars, versus the old, temperamental carburetor-fitted cars....

exactly. On old fuel controls the fuel flow was either set in the shop or on the run up pad. You can do the same thing with a carb on a car (or airplane )
FADEC does it all automatically.
like everything else in the world, the basic part of this is we have gone from a fully mechanical system to a system controlled by electronics.

Again, as I said above, FADEC is about performance, but it does much, much more.

The FAA has a nice document on FADEC here: https://www.google.de/url?sa=t&rct=j&q= ... agw4axmR8S

I'm now quoting from the FAA doument:

FADEC Advantages
FADEC shares advantages with electronic ignition and EEC systems, but it takes power management several steps further. FADEC combines throttle, prop, and mixture controls into a single control. Every throttle setting at any altitude results in the optimum power/prop RPM/mixture combination. This enables pilots to realize fuel economy that would only have been dreamed of previously.

Automatic engine performance monitoring constantly provides over-speed and over-boost protection throughout the operational range. Pilots can command maximum power and the system will deliver just that and no more. There is no possibility of exceeding limitations. FADEC also features diagnostic processes that constantly monitor the health and well-being of the aircraft powerplant. The diagnostics are very good at defining small problems before they become big problems. It’s not surprising that FADEC delivers big returns in increased fuel efficiency and reduced maintenance expense.

And that is the whole point of it. And also because the IR 727-200 was lacking FADEC it crashed. There were other reasons, too, but it mostly comes down to the fact, that the pilots firewalled the throttles and "destroyed" the engines, because FADEC wasn't there to save their lives and the lives of their passengers and cabin crew. And speaking in a broader sense again: Without FADEC we would way, way more aircraft crashes per year and have many more dead pax and crew. Yes, FADEC boosts performance, but mostly it saves lives.

Just an addition, since everyone has been focusing on engine control - the FADEC also provides safety features, such as surge detection, automatic engine shutdown in certain conditions, etc, and pilot relief functions such as auto-relight.

r2rho wrote:

Just an addition, since everyone has been focusing on engine control - the FADEC also provides safety features, such as surge detection, automatic engine shutdown in certain conditions, etc, and pilot relief functions such as auto-relight.

Those are not necessarily FADEC functions. Simply put, a FADEC/EEC protects against overboost, overtemp and overspeed. Nothing more. The functionos you are talking about, relight, auto shutdown are not actually part of the FADEC/EEC but software installed into the aircraft monitoring systems. Surge detection is not really part of the FADCE/EEC but the FADEC/EEC minimizes surge probability by ensuring the proper fuel schedulig. Generally, engine surge is a bleed related problem.

For those unfamiliar with the EEC, it stands for Electronic Engine Control interchangeable with FADEC.

For those unfamiliar with the EEC, it stands for Electronic Engine Control interchangeable with FADEC.

I know this is a pedantic point, but I believe they are different. The FADEC had full authority over the engine.-
The EEC has authority over the fuel system.
The RB211-535 on the B757 has an EEC mounted in the aircraft electronics bay. The EEC keeps the engine in check, but does not control it.
The RB211-524G on the B744 and B767 has an EEC on the engine. This works exactly like today's FADEC, but has no authority at all over the air system. Control of the VIGVs and the surge control bleed valves is completely separate.

oldannyboy wrote:

To make things very easy to understand to non-geniuses like me I think of FADEC as the equivalent of the electronic injection in the engines of modern cars, versus the old, temperamental carburetor-fitted cars....

Not a bad analogy .... Think of it as “throttle by wire” with built in monitoring and protections. In an old DC-9 firewalling the thrust levers will probably result in a limitation exceedance. With a fadec the computer will prevent the engine from going to hot, too fast, too slow, etc. without any pilot input.

The connection between the flight deck and the engine is also all digital in a FADEC aircraft. In a mechanical set up there is a direct cable from the throttle levers to the fuel control. For FADEC the throttle lever movement is converted into a digital input which is sent to the engine through a data bus. Just like a flight sim on your computer does.

That IR crash has to be only one I’ve heard of where lack of a FADEC was causal to the crash. FADECs and the EEC do lots of things but they weren’t installed to save lives. They allowed better engine life as the result of precise fuel scheduling. They allow for completely automated starts and, more importantly, protect the engine from start malfunctions, hot starts, starts that take too long. The EEC replaces the old hydro mechanical fuel controllers and throttle cabling , while the FADEC handles the starting, the protections. Related but two different functions.

Jet engines are pretty tough and over “boosting” a JT8D at 2.14 shouldn’t be damaging. God (Allah) only knows the maintenance and parts availability in the 21st century on an out-of-date, unsupportable (due to embargo and sanctions) engine. I’d take that accident as evidence of FADEC design being a life saver rather skeptically.

Also, the TF-39, which had a horrible early “childhood”, had vastly faster spool up times than any new FADEC engine I e flown. Touch and goes were easy, while the new FADEC engines are much slower. Admittedly, a nighttime compressor stall could be enlightening, literally. Which what FADEC/EEC engine’s do NOT do.

GF

GalaxyFlyer wrote:

That IR crash has to be only one I’ve heard of where lack of a FADEC was causal to the crash. FADECs and the EEC do lots of things but they weren’t installed to save lives. They allowed better engine life as the result of precise fuel scheduling. They allow for completely automated starts and, more importantly, protect the engine from start malfunctions, hot starts, starts that take too long. The EEC replaces the old hydro mechanical fuel controllers and throttle cabling , while the FADEC handles the starting, the protections. Related but two different functions.

Jet engines are pretty tough and over “boosting” a JT8D at 2.14 shouldn’t be damaging. God (Allah) only knows the maintenance and parts availability in the 21st century on an out-of-date, unsupportable (due to embargo and sanctions) engine. I’d take that accident as evidence of FADEC design being a life saver rather skeptically.

Also, the TF-39, which had a horrible early “childhood”, had vastly faster spool up times than any new FADEC engine I e flown. Touch and goes were easy, while the new FADEC engines are much slower. Admittedly, a nighttime compressor stall could be enlightening, literally. Which what FADEC/EEC engine’s do NOT do.

GF

Hello Sir,

I would LOVE to hear more about your Galaxy & TF-39 flying... very interesting!

Regards,

Danny

N353SK wrote:

oldannyboy wrote:

To make things very easy to understand to non-geniuses like me I think of FADEC as the equivalent of the electronic injection in the engines of modern cars, versus the old, temperamental carburetor-fitted cars....

Not a bad analogy .... Think of it as “throttle by wire” with built in monitoring and protections. In an old DC-9 firewalling the thrust levers will probably result in a limitation exceedance. With a fadec the computer will prevent the engine from going to hot, too fast, too slow, etc. without any pilot input.

old DC-9 = Volvo Amazon 122S

FADEC 777 = Volvo V90

GalaxyFlyer wrote:

That IR crash has to be only one I’ve heard of where lack of a FADEC was causal to the crash.

Air Florida?

Plane wasn't climbing yet the pilots never touched the throttles, FADEC would have ensured the correct takeoff power from the start and tbey would have cleared that bridge.





Sent from my SM-N920T using Tapatalk

NO, it wouldn’t have set the correct thrust. Auto-throttles, if installed (not available), would have selected the correct thrust, but a FADEC (more precisely the EEC), using manual throttles will only set the thrust as required by the throttle angle set by the pilots. In any case, IIRC, AF 90 did NOT have engine anti-ice ON, thus the EPR probes were blocked by enough ice to result in incorrect EPR reading. The pilots set the INCORRECT EPR by reference to the iced EPR probes. A FADEC under the same conditions would reacted identically.

Look up high altitude ice crystal ingestion and incorrect power setting. Basically, ice crystals in sufficient can be ingested faster than the anti-ice heat can melt the ice. With the probes blocked, the EEC is sensing the heated air trapped the probes. As the sensed air warms, the EECs react by retarding the thrust levers toward idle. Most often occurs in high level, tropical cirrus cloud.

GF

GalaxyFlyer wrote:

NO, it wouldn’t have set the correct thrust. Auto-throttles, if installed (not available), would have selected the correct thrust, but a FADEC (more precisely the EEC), using manual throttles will only set the thrust as required by the throttle angle set by the pilots. In any case, IIRC, AF 90 did NOT have engine anti-ice ON, thus the EPR probes were blocked by enough ice to result in incorrect EPR reading. The pilots set the INCORRECT EPR by reference to the iced EPR probes. A FADEC under the same conditions would reacted identically.

Look up high altitude ice crystal ingestion and incorrect power setting. Basically, ice crystals in sufficient can be ingested faster than the anti-ice heat can melt the ice. With the probes blocked, the EEC is sensing the heated air trapped the probes. As the sensed air warms, the EECs react by retarding the thrust levers toward idle. Most often occurs in high level, tropical cirrus cloud.

GF

EXACTLY this ^^^

I love FADEC (just as I love modern EFI cars and loathe carbs) but this is very similar to a car going into limp mode or misfiring due to a rich/lean condition because of a faulty MAF or o2 sensor.

For clarification to the other comments, computers are totally reliant on data inputs for performance, unlike the old days - they are "garbage in, garbage out" and FADEC likely wouldn't have known what to do in this situation - I say likely because perhaps there's some safety program at TOGA which may ignore an input and run off of predetermined fuel and performance programs. The problem here is that the EPR's weren't "implausible" - they were just off a bit. Most computer systems won't cut data or revert to an open-loop solution if the data is within a plausible range. If, however, the ERPs went dead or to 1 (aka implausible) I'd imagine FADEC is programmed to do something else beyond just cut power. Maybe someone else can chime in on the fail-safe programming though.

In any event, ironically the AF flight crew had the CAPABILITY to firewall the engines and achieve full thrust, which wouldn't have been there with FADEC from what I understand, so the comment about FADEC saving their lives might actually be the opposite?

In RR experience, a FADEC FAIL would post and the crew QRH procedure would be to select NI CONTROL. Hard to do on the roll

It might be a FADEC FAULT, not a FAIL.

Where electronic engine controls have really improved aviation is in tactical fighters. Primary examples are the F-14. The A models had the TF-30, the first afterburning fan engines. While good enough, just barely, in F-111 because it’s mission was mostly straight and level F-14 operates shipboard and in aerial combat. On launch in afterburner it was susceptible to stalls and stagnation especially if it got inlet of steam on the stroke. At high AoA and low speed or with high yaw and pitch rates, it was also very susceptible to stalls and rollbacks. Off the ship, a stall was very close run recovery—sometimes a ride up the rails. At altitude, it was recoverable, but one generally loses the fight when engine out. FADEC/EEC F101 was trouble-free and burner lights reliable regardless of conditions. The EEC just controls the engine with so many more parameters, the digital analysis of those parameters being continuous and instantaneous. Trouble-free and much more reliable.

In civil applications, the advantage is in maintenance costs. A hydro mechanical engine controller operates with vastly fewer inputs and, while not seen in the cockpit, is much rougher in handling transients. It’s all similar to soak and compression ignition automotive engines. We’re seeing cars with 120hp/liter with turbos and electronic controls, something that was barely achievable in F1 engines 40 years ago. Diesel truck engines are cleaner, produce another 150hp in a 15L engine with better economy.

GF