EFIS comparator is unable to compare one or more of the parameters that follow: altitude, airspeed, roll attitude, pitch attitude, heading, radio altitude, flight director, localizer or glideslope.

There is a mismatch between the same side and opposite side data.

There has been a mis-compare of engine related flight critical parameters.

DCU doesn't receive valid data from the left IOC or the PWR has stopped to operate.

Communication between the PFDs has failed.

There has been a mis-compare of engine related flight critical parameters.

DCU does not receive valid data from the right IOC or the PWR has stopped to operate.

There has been a miscompare of warning, caution, advisory, status or aural warnings for more than 20 seconds.

DCU fan has failed.

Channel A or B in the DCU has failed.

The manual mode does not operate (on the ground only).

FDR has failed.

IAPS has detected a fan failure, over-temperature, or a temperature sensor failure.

Communication between the MFDs has failed.

RDC fan has failed.

Channel A or B of the RDC has failed with no loss of functionality.

AURAL WARNING DCU A switch has been set.

AURAL WARNING DCU B switch has been set.