1) Hoses connect to them 
Cover of the Dubstar album Goodbye (scanned) ...
The fuel tanks or cylinders are tanks of liquid propane gas. They normally stand in the corner of the basket leaving room for the pilot and passengers. Padded covers surround the cylinder - just in case of a bumpy landing - while rubber encased armoured pipes carry the fuel up to the burner which is supported above the basket on flexible nylon rods...