Tuc and Chug,
Thank you both for the clarification. You will understand I am not using the benefit of hindsight to justify the decisions taken in 1994, sorry if that caused confusion. If you were referring to the Block 2 upgrade, then I don't believe they were.
Many early FADEC malfunctions were the definately result of incorrect procedures, which we now understand better and have amended our drills to compensate. But the BD recommendation to rewrite did not happen and no further verification work took place, as far as I'm aware.
As simple aircrew, the idea that understanding the design can change the status of an aircraft from unairworthy to airworthy seems counter-intuitive. Or am I confusing the terms 'airworthy' and 'safe'?