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How significant is a simple aircraft equipment/computer reset ?

 How significant is a simple aircraft equipment/computer reset?

  •  Why reset has become a part of certain AMM (Aircraft Maintenance Manual) procedures?
  • Though AMM may not tell you, it's a 'Reset', its instructions to 'Switch OFF/ON' or 'Pulling a CB(Circuit Breaker)' is a form of system reset apart from the electrical equipment safety aspect of it.
  • The System reset is often needed to clear faults recorded by systems before or even possibly during maintenance.
  • Some systems use fault latching mechanisms, i.e. , once a fault has been registered, it gets latched. Now the input system (Computer) will be considered unavailable for the user system (Computer), until a reset.
  • Failing to follow AMM fully & neglecting the 'Reset' step had forced an Airbus aircraft to undergo 'Alternate Flight control law' in the past.
  • The Event:

  • During the flight, due to ADR-1 (Air Data Reference) fault, the ELAC (Elevator and Aileron Computer) latched the ADR#1 (failed unit) & used ADR-2 & -3 data.
  • Upon landing, ADIRU-1 was swapped with -3, to place ADIRU-3 under MEL & the aircraft departed without an ELAC & SEC 'Reset'.
  • Now ELAC read both ADR-1 & -3 as INOP, due to latched memory. Without ADR-1 or -3, only ADR-2 was treated available & Flight Alternate Law applied.

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