Incident at Heathrow
A long time ago someone invented the retractable undercarriage. Shortly afterwards pilots started landing wheels up, not often and usually when they were tired or distracted. At first managers said we must have " more rigour" and I'm sure that if Prune had been around there would have been pages of sanctimonious tosh. Sadly "rigour" failed to solve the problem and eventually the bean counters worked out that warning systems were cheaper than wheels up in the long run and the problem was solved.
Sadly aircraft kept flying into the ground, not often just when the pilots were tired or distracted, once more the managers called for "rigour" . Unfortunately aircraft continued to hit the ground so GPWS was invented and it hardly ever happened. When it did crews were accused of lack of "rigour". Fortunately along came EGPWS and the problem was largely solved.
I am sure the managers would like to keep Airbus cowlings closed by the application of more "rigour". Unfortunately I am equally sure that the problem will reoccur because at the end of the day most people involved in aviation are human.
I have no idea if the correct engineering procedures were followed in this case, nor do I know how easy it would have been to spot on the walk round. I am pretty sure however that if there had been an ECAM or a large flag hanging off the engine the aircraft would not have got airborne.