AFAIK airlines have to allow your mobility scooter to travel free of charge? Just make sure you inform the airline beforehand and have all the details available (make, model, name, dimensions, battery type etc).
If it's a dry cell battery it'll have to be disconnected and isolated (usually by removing the key) before it can be loaded onto the aircraft. If it's a lithium battery, it has to go in the cabin with you in a suitable container.
I've had everything from 7kg fold up type scooters to the 100kg+ beasts