Tengo 30 minutos por escala

[ROBINDESBOIS]

I have 30 minutes at every stopover??? Is it OK?

[Rusty]

It would be understood, but we usually say something like "I have a 30-minute layover at each connection/leg."

[ROBINDESBOIS]

But if you work at the airport and there are lots of flights that make a stopover at the airport and you have 30 minutes to clean the aircrafts.???

[Rusty]

It takes 30 minutes every layover to clean the aircraft.
I have 30 minutes to clean the aircraft during each layover.
I have a 30-minute window for cleaning the aircraft during each layover.

[poli]

Stopover usually implies a longer period of time, perhaps a day.
Example: On my way to Hawaii, I had a stopover in San Francisco to visit a friend.

Layover may be an term specific to the USA. Perhaps a British person will have a look at this, and confirm it.