fadec cant talk to engine via throttle controls when the system has lost power or crashed, default then is to roll back. Its not a `oops dont know what to do lads, give it FULL POWER` doesnt work like that
Air India Crash
- Thread starter Grim5
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fadec cant talk to engine via throttle controls when the system has lost power or crashed, default then is to roll back. Its not a `oops dont know what to do lads, give it FULL POWER` doesnt work like that
Except in the 787 where a thrust lever position resolver is powered by FADEC so they can control engine speed.
Not if the throttle cannot communicate with it. There's no magic link, so if the system has failed , everything goes to failsafe
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A simple google will tell you this :-
There is a dual-throttle resolver per thrust lever. The dual resolver contains two resolvers in one package driven by a single, common shaft. One resolver provides TRA input to Channel A and the second to Channel B. The FADEC provides electrical excitation for the resolvers.
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And a simple google will also tell you if the aircraft is electrically dead, no magic link exists for throttles to communicate with the fadec. It literally doesnt work like magic voodoo.
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‘Electrically dead’ needs defining, given the FADEC generates its own power independent of the aircraft electrical systems.
The FADEC provides electrical excitation for the resolvers....
A FADEC (Full Authority Digital Engine Control) power supply provides the necessary electrical power for the FADEC system to operate the engine. It typically involves a 3-phase AC power source, often from a permanent magnet alternator (PMA) on the engine, and may include features like programmable output voltages, current limits, and fault simulation.
Here's a more detailed breakdown:
1. Primary Power Source:
- Permanent Magnet Alternator (PMA):
A PMA is a common source of power for FADECs. It generates 3-phase AC power directly from the engine's rotation.
- External Power Source:
In some cases, especially during ground maintenance or testing, an external 400Hz AC power source with transformers and inductors may be used.
- Independent, Isolated Outputs:
A FADEC ideally requires two independent, isolated 3-phase outputs to ensure redundancy and prevent a single point of failure from impacting both engine channels. - Programmable Parameters:
Features like programmable output voltages, current limits, and frequency ranges allow for flexibility in testing and operation. - Monitoring and Fault Detection:
The power supply should measure and report per-phase voltages, currents, and waveforms to ensure proper operation and detect potential faults, like a failed diode in the rectifier. - Fault Simulation:
The ability to simulate faults (e.g., a failed diode) is crucial for FADEC development and testing.
- Dual FADEC System:
Modern aircraft utilize dual FADEC systems, where each engine is controlled by its own independent FADEC. This redundancy ensures that if one FADEC fails, the other can continue to operate the engine.
- Fail-Safe Design:
FADEC systems are designed with fail-safe mechanisms to prevent engine over-limits and ensure safe operation even in the event of a fault.
- Redundant Power Sources:
Redundant power sources, such as backup batteries or auxiliary power units (APUs), may also be incorporated to maintain FADEC power in case of main power loss.
- Commercial Aircraft:
FADECs are standard on most commercial aircraft, enabling safer, more efficient, and fuel-efficient engine operation. - Military Aircraft:
FADECs are also widely used in military aircraft, offering enhanced performance and capabilities. - Retrofitting:
Older aircraft are often retrofitted with modern engines utilizing FADECs to improve performance and efficiency.
Not really needs defining. Doesnt matter if the engines are self contained power, if every other system cannot talk to them. Default failsafes will roll back the engines to idle or you`ll get random run aways.
Also the 787 has batteries too.
And again since you love to copypasta.
Doesnt matter if it all self contained if the rest of the aircraft cannot talk to it. No magic link exists between the throttle in the cockpit and the fadec in the engine (its a box on the side of the engine) if the cockpit controls are electrically dead, since they are not mechanical with cables, its all done with wires.
I’m more surprised that something actually worked on a TriStar tbh………
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Harsh but fair. Mind you, the RAT was there for when things didn’t work in the first place
Harsh but fair. Mind you, the RAT was there for when things didn’t work in the first place
Sorry I was VC-10’s a running joke at Brize with the TriStar…..
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Sorry I was VC-10’s a running joke at Brize with the TriStar…..
All good fun - no FADEC’s in sight back then either!
Does this image help and more info below and use the info I posted above too?
Alternator provides power to the FADEC while the engine is running and each engine has one. In my top reply it is mentioned as PMA :-
Permanent Magnet Alternator (PMA):
A PMA is a common source of power for FADECs. It generates 3-phase AC power directly from the engine's rotation.
TLA - Throttle Level Angle, Reversers and switches for the engine are connected to the FEDEC and powered by the FEDEC via the alternator (PMA) in each engine or the batteries, or the RAT (Ram Air Turbine) if deployed too or the APU (Auxiliary Power Unit) if used too.
In a Full Authority Digital Engine Control (FADEC) system, the throttle lever angle (TLA) is a crucial input that determines the engine's thrust. The TLA, measured by a resolver or similar device, is sent to the Engine Control Unit (ECU) which then calculates and regulates engine parameters like fuel flow to achieve the desired thrust level.
Here's a more detailed breakdown:
- Throttle Lever Angle (TLA):
The position of the throttle lever in the cockpit, which the pilot manipulates to control engine thrust, is known as the TLA.
- FADEC's Role:
FADEC systems use the TLA, along with other inputs like air density, temperature, and engine parameters, to determine the optimal engine operating conditions.
- ECU (Engine Control Unit):
The "brain" of the FADEC system, the ECU receives the TLA signal and calculates the necessary adjustments to fuel flow, ignition timing, and other parameters to achieve the desired thrust.
- Resolver or Similar Device:
A resolver is a type of transducer that accurately measures the angle of the throttle lever and converts it into an electronic signal for the ECU.
- Thrust Calculation:
The ECU uses the TLA and other inputs to determine the required thrust and then adjusts the engine's fuel flow and other parameters to produce that thrust.
- Pilot's Input:
The pilot's throttle input, in the form of the TLA, is a direct command to the engine, telling it how much thrust is needed.
- FADEC Limiting:
FADEC systems can be programmed to limit engine parameters like temperature or speed. For example, if the pilot sets the TLA to a point that would cause the engine to exceed a temperature limit, the FADEC might automatically reduce the TLA to stay within the limit.
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Does this image help and more info below and use the info I posted above too?
He’s not questioning that it remains powered, just that if it loses all control inputs (turbine disc goes through the wing severing all wiring bundles, much like QF32) what reaction does the FADEC have?
Does it remain at the current thrust setting, roll back to idle as a failsafe or shutdown completely.