Quote:
While it is true that it gets inputs from ADIRU 1 and 3, it is also true that
it contains gyros !!
Not so true. It does not contain gyros. It's containing a IMU (Inertial Measurement Unit) described as "
Inertial Measurement Unit (IMU). It contains three single-axis rate sensors and their temperature
probes, two acceleration sensors and their temperature probes, one IMU board and one mechanical
structure. This assembly is connected to the Programmed Motherboard "
It is not an IRU (Inertial Reference Unit) it ONLY detect it's position in space, not movement in it. And in regards to ADIRU inputs.
ADIRU (IR1 or IR3)
Two ARINC 429 high-speed buses provide the ISIS indicator with the ADIRU ground speed information. This information is used as a backup source for the ISIS ground/flight condition.
In normal configuration, the parameters used by ISIS indicator come from the ADIRU 1.
When a failure is detected, switching to the ADIRU 3 must be done manually through the ATT/HDG selector switch on the SWITCHING panel.
Captainflame:
As written (by me among others) in previous posts, the ISIS is a self contained instrument providing Airspeed from stby pitot, attitude from internal gyros, Altitude from STBY static ports, and slip/skid info from accelerometers,
(Since I have not much more than this on my FCOM)
Captainflame: What happens when ALL ADIRUS fail?