[nradov]

Should there be an expiration date on grandfathering of airliner type certificates? Should manufacturers be required to update designs for new production airliners after, let's say, 30 years? The original Boeing 737 entered service in 1968 so even working at a slow pace with minimal resources they could have redesigned and recertified it multiple times in that period.

[error503]

Personally I think so. Type certifications should expire after some reasonable time, and require a full re-certification under current rules and with current design review practices. I think this would also have other benefits, by discouraging improvements to e.g. fuel economy or pilot procedures slightly less, since the cost of re-certification is inevitable rather than something that can be avoided.

Grandfathering aircraft that exist indefinitely makes sense to me, but I don't see why designs should be grandfathered indefinitely for new builds, when we have learned a lot and increased our expectations significantly in the intervening years.

[TylerE]

For that matter there are still plenty of DC-3s in active service, and those are all over 80 years old at this point. Not nearly as big a deal as it might sound - the biggest wear item on a commercial plane is actually cabin pressurization due to the long term fatigue characteristics of aluminum. DC=3s aren't pressurized.

[nradov]

I'm asking about changing policies for newly manufactured airliners, not specific airplanes that have already been built. No one has used a DC-3 for FAA Part 121 scheduled airline service in decades.

[TylerE]

There are a number in regular commercial use (including passenger flights) in Canada which is a very similar regulatory regime. There are multiple US operators of the Basler turboprop conversion.

[michaelnik]

No need. That could be done be through the system of Airworthiness Directives (ADs) I think.