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A turbine engine with a dual channel FADEC has a single channel fault. Which of these actions should the crew take?
  • A
    Continue the flight, since the healthy channel automatically assumes full engine control.
  • B
    Intervene and take manual control of the engine, due to the loss of the redundancy.
  • C
    Set the power of the affected engine to IDLE, because engine indications are completely lost.
  • D
    Avoid a high-power setting on the affected engine, due to single-channel limitations.

Due to the nature of FADEC (Full Authority Digital Engine Control) systems, failures must be well protected against. If there is a full FADEC failure with no backup then an engine will usually just stop working, as things such as the fuel supply will stop, or at least stop being regulated in any case.

This means that FADEC engines need back up systems for redundancy. This can either be achieved with a single FADEC system and a hydromechanical back up, or more commonly with a dual channel FADEC system. This makes the FADEC system 'single fault tolerant', meaning that any one fault on its own cannot stop the engine completely.

In the case of this aircraft (dual channel FADEC system), the second (healthy) channel will take over if there is a single channel fault, and the engine itself will not perform any differently. As soon as it is on the ground it will be grounded until fixed, as a single channel FADEC with no back up control system would not be acceptable to run an engine.

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