Is there any regular (normally) air bags scheduled maintenance required?
The only “maintenance” is to observe the airbag light on the dash when you start the car to ensure 1. that the light works and 2. ensure that it goes off in after few seconds and stays off.
Of course, not having a frontal collision greatly extends the life of the airbags too. 
Most manufacturer’s maintenance schedules include a diagnostic check of the air bag mechanism/circuitry after ten years. I would strongly suggest that someone have this done (at the dealership!) once the car is 9 or 10 years old.
And, of course, if one buys a used car, this is something that needs to be checked a.s.a.p. since one never knows exactly what has gone on with a used car.