All of the above, planes see a lot more stress than cars. Each time an aircraft flies and lands without doing a quick turn while its initial preflight is still valid: It's inspection time. I'm airforce and we have 4 different inspection types on the c-130 variant I work, for daily flightline use. Post Flight, Pre Flight, BPO/PRE (post flight and pre flight combined) and a thru flight. The most gruelling inspection by the book is the post flight/pre flight. Though if you read into the rules of following our maintenance data all of these inspections must be completed the same. Every single mm of exterior and interior part of the plane that is visible by eye (flash light assistance for dark areas) has to be looked at.
Each type of inspection has a time limit on how long it's good for before it has to be accomplished again. Even if the plane doesnt fly.
BUT if it makes you feel any better, we recently started retiring our AC-130H fleet here at cannon afb. They were made in the mid/late 60's, that's 50 years of service on the airframe, and at least 30 of those years were with a set of cannons and guns hanging out the side of it putting even more irregular forces onto the structure. so I'm pretty sure our little aluminum cars can last a very long time if treated right
Complimentary night vision pic I took while we were somewhere, at some point....
