Airbus 320F system functionality tests.
 

I have noticed from various accident and incident reports that the Airbus 320F performs a number of tests in flight that are transparent to the crew.
For example the incidents with the nose wheel leg at ninety degrees it was established, that the material fatigue of the anti-rotation lugs was produced by the pre-landing steering tests performed by the BSCU. After centering the nose wheels the BSCU would command the nose gear to rotate 2.5 degrees to the left, center again, 2.5 degrees to right and center again. Such a cycle takes about 5 seconds. In average 57 such cycles are performed for each flight.Airbus subsequently modified the software of the BSCU to reduce the number of left/right pre-landing steering test cycles to 8
The accident report to the A319 at LHR mentions about a braking system self test ( which one of the brake units failed)
My question is what other system testing is going on that the pilot is unaware of?

Breath tests in the air conditioning filter system?

Urine tests in the forward toilet?

Mental disturbance checks from the FDR?

This one could run and run!

Hopefully with some productive answers rather than nonsense.

Self testing
 

Can't speak as an expert on all A320 systems (worked on software for the 320 FQIS in the 80s) but its likely that all software managed systems in any modern aircraft will have built in self test (BIST/BIT/BITE) routines that run at start-up, at shut-down and perform monitoring and test processes during flight.

This is normally passive in nature (checking sensor values and states are in range) but I'm sure many systems will perform more "active" tests to ensure operational safety before engaging key systems.

Engines and gearboxes etc also have Heath Usage Monitoring Systems (HUMS) built into the software. This is BIT (though normally passive) by another name.

Self tests are all over the place and help systems spot potential issues and problems BEFORE they become significant - often allowing maintenance and replacement of parts before anything fails to a level that would cause a cockpit warning.

The pilot would not be aware of any of this.

Thanks Mascot. The BSCU test seems the most aggressive with it testing the nosewheel steering a ridiculous number of times.

I know the forward coffee makers test themselves continously. To no avail, I might add.