Originally Posted by kiskaloo
On the other hand, considering the 787's testing was trouble-free enough for the FAA and EASA to find the 787 suitable for ETOPS-180 operations and the plane flew without incident for over a year, which convinced the JTSB that the 787 was suitable for ETOPS-180, to issue a new ruling that finds the 787 not suitable for ETOPS-180 operation might call into question again how these agencies certify twin-engined aircraft for ETOPS at EIS and that could impact the suitability for ETOPS at EIS for new twins like the A320neo, A350 and 737 MAX.
Pretty straight forward really - they made a determination based on the evidence and granted approval. Subsequent events raised significant concerns about the capability, those events were not in evidence at the time the original determination was made.
Accordingly the evidence was reviewed and a new position, based on the additional evidence determined.
Does it call into question how certification works?
Almost certainly not. A test and compliance regime would be determined and certification granted if passed. If subsequent events mean a type no longer passes then their accreditation is reviewed.
Sounds like a sensible pragmatic process. Where's the problem? The battery fire? Sure that's bad, but if it didn't happen in testing then there's no reason to fail the accreditation process. And if subsequent events contradict the genuinely obtained results during certification then you review what certifications are granted.
How is any of this hard to understand? Things can change and the system is flexible enough to cope with that.