Originally Posted by
infrequentflyer789
For EASA-FAA, bilateral agreements mean that each basically rubber-stamps the other's approvals. They are, however, completely independent organisations and each has its own rubber stamp.
No, not a rubber stamp. The FAA FAR and EASA CS regulations are for the most part the same, but there are some significant differences. When a new TC or ATC is applied for, there is a meeting between EASA and the airframer and they agree to a list of 'significant regulatory differences' between the relevant FARs and CSs - this is documented in a CRI (Certification Review Item - it's basically what EASA calls an FAA Issue Paper). For the CS regulations listed in that CRI, compliance must be shown separate to the FAA compliance (btw, the FAA doesn't call them FARs, they are CFR (Code of Federal Regulations) - and the FAA can be quite anal about it if you call them the FARs).
In my case, the primary regulation I needed to worry about being different was 25.901(c) - the FAR basically says 'no single failure shall result in an unsafe condition' - while the CS basically says you need to comply with CS 25.1301 (which means a probabilistic analysis). It's a subtle but significant difference - interestingly it can be easier to show compliance for the CS than the FAR. Items on the list of differences often drive their own, dedicated CRIs, or sometimes CAI (Certification Action Items). Similar to FAA Issue Papers, all CRIs and CAIs must be addressed and closed prior to type cert.
Now, EASA makes a separate agreement where they decide if they'll delegate approval of a particular item to the FAA, or retain it themselves. Again, in my case, EASA retained 25.901(c). On the 747 there was a CRI for 25.901(c) we had a number of meetings with EASA and even did some simulator sessions with EASA pilots before we were able to close the CRI.
In effect, EASA does do their own certification, but only for particular items that they decided were of particular interest.