Today our supplier brought us a rental Invacare model XP0100 Ser, # 371285. Have never used a portable before. This must be an older model as it weighs more than 4.98 #. We will be traveling in the future by plane, Is this unit approved to be used in the airplane? There is no owners manual with it. What do I need to be concerned about? Any suggestions for a new user will be appreciated. Thank you