Air Data Inertial Reference Unit (ADIRU)
The ADIRUs provide inertial position and track data to the FMC as well as attitude, altitude
and airspeed data to the displays. The ADIRUs process information measured by internal
gyros and accelerometers, and from air data module inputs, the alpha vanes and other
systems.
Air Data
The pitot static system is comprised of three separate pitot probes and six flush static ports.
Two pitot probes and four static ports interface with the air data modules. The remaining
auxiliary pitot probe and alternate static ports provide pitot and static pressure to the
standby instruments. The auxiliary pitot probe is located on the first officer’s side of the
airplane.
The air data modules convert pneumatic pressure to electrical signals and send these data
to the ADIRUs. Each pitot air data module is connected to its on–side pitot probe; there is
no cross connection. The air data module connected to the Captain’s pitot probe sends
information to the left ADIRU, while the air data module connected to the First Officer’s pitot
probe sends information to the right ADIRU. The remaining air data modules are located at
the balance centers of the Captain’s and First Officer’s static ports. The air data module
connected to the Captain’s static ports sends information to the left ADIRU, while the air
data module connected to the First Officer’s static ports sends information to the right
ADIRU.
