yxcapt highlights a very important point. . .. .The design standards regularly change to reflect both industry design and manufacturing capability and public (political) will.. .. .If one looks up the current rules, they should be viewed as a guide, as their application will be limited.. .. .If you want to find a likely answer for a specific aircraft, you need to check the relevant type certificate data sheet for the design standards issue for which the certification was determined .... then find a copy of the superseded rules to find the answer which you seek.