Reply to post: Re: Negligent certification

Boeing... Boeing... Gone: Canada, America finally ground 737 Max jets as they await anti-death-crash software patches

lglethal Silver badge
Boffin

Re: Negligent certification

This is actually one of the biggest topics for disagreement between the Americans and the European regulatos. It's called Grandfathering. The Americans love it, the Europeans do there best to block it.

Basically, it means that for a small change you dont need to recertify the full aircraft. Because recertification is VERY expensive. But then the question becomes whats a small change? And how many small changes before it constitues a new aircraft and needs to be recertified?

As a thought experiment at uni, we were able, under the American rules, with many little steps, to bring a wood and cloth plane from the first world war up to a fully metal enclosed passenger aircraft (think early 50's level) on a single type certificate.

OK in reality, you wouldnt get that far (as someone would eventually show a modicium of sense), but it gives you an idea of the problems with Grandfathering.

Now i dont know enough about the changes between the 737 and the 737 MAX, but maybe it should have been recertified. At the very least, there should have been a much higher level of scrutiny placed on the implementation of this AoA feature. I have absolutely never heard of any system like that which does not use multiple sensors (min 3) and a voting system. To allow a single sensor to control something like this with a foreseeable risk of crashing the aircraft is, well, frankly criminal.

(from a 15 year veteran of the Aerospace industry)

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