airworthiness certificate
NTSB concludes the most exhaustive and expensive enquiry ever with a "don't know FOR CERTAIN but suspect wiring short through fuel probes" in the centre tenk of B747-100.
Still huge uncertainty on the B737 rudder hardover occurrences.
B767 seems it may have elevator control system faults.
Concorde is grounded because FOD on runway burst tyre and the fuel tank got punctured.
Which of these aircraft meets all the airworthiness requirements then?