[tzs]

From the IEEE article:

> The fault-tolerant ADIRU was designed to operate with a failed accelerometer (it has six). The redundant design of the ADIRU also meant that it wasn’t mandatory to replace the unit when an accelerometer failed.

This seems unwise to me. I could understand if the rule was that you could put off replacing a failed accelerometer until the next regular maintenance. If it is OK to simply never replace it, then why not just ship the plane with five and save money?

[einhverfr]

> I could understand if the rule was that you could put off replacing a failed accelerometer until the next regular maintenance.

I think that's the idea. Whether or not it is followed in practice is another matter, and testing further failures was not the priority it should have been.